K2 Campaign 0 Findings

• by Martti_Holst_Kristiansen

  First of all I would like to thank Andrew Vanderburg (Harvard-Smithsonian Center for Astrophysics) and Al Schmitt (HEK) for providing us with the new K2 C0 LCs and making this possible. My findings below are not chronological ranked (this will be corrected). Feel free to add/comment and please let me know if additional corrections need to be made.

  ---

  There seems to be quite a few glitches, (let me know so more can be added):

  1941.15 BKJD

  1955.75 BKJD

  ---

  CV/DN:

  ID 202061318

  ---

  Planet Candidates:

  ID 202071690 (Single transit)

  ID 202095298 (P=2.891)

  ID 202060171 (P=3.303)

  ID 202059360 (P=3.671)

  ID 202072704 (P=2.664)

  ID 202071289 (P=3.047)

  ID 202088212 (P=2.621)

  ID 202068800 (Single transit)

  ID 202066537 (P=6.906)

  ID 202090723 (P=6.140)

  ID 202071828 (P=4.707)

  ID 202093020 (P=4.134)

  ID 202067861 (Single transit)

  ID 202072507 (Single transit)

  ID 202089948 (Single transit)

  ID 202066192 (P=3.290)

  ID 202066227 (Single transit)

  ID 202071448 (Single transit)

  ID 202092782 (P=13.362)

  ID 202088403 (Single transit)

  ID 202088428 (Single transit)

  ID 202087156 (P=1.894)

  ID 202071394 (Single transit)

  ID 202087494 (P=?)

  ID 202085597 (P=1.815)

  ID 202126847 (P=4.170)

  ID 202126852 (P=2.796)

  ID 202126849 (P=3.799)

  ID 202083828 (P=14.568)

  ID 202066212 (P=6.179)

  ID 202081797 (Single transit)

  ID 202126884 (P=5.320)

  ID 202137637 (P=6.620)

  ID 202137209 (P=2.374)

  ID 202126888 (P=1.847)

  ID 202136151 (P=6.385)

  ---

  Eclipsing Binaries:

  ID 202084843 (Maybe additional transits at: BKJD 1945.05 & 1963.4)

  ID 202092842 (P=ø)

  ID 202060523 (P=16.407)

  ID 202060577 (P=1.019)

  ID 202071994 (P=4.060)

  ID 202071945 (P=ø)

  ID 202072917 (P=ø)

  ID 202071902 (P=ø)

  ID 202072485 (P=14.634)

  ID 202060447 (P=2.025)

  ID 202060506 (P=1.959)

  ID 202072929 (P=3.048)

  ID 202072486 (P=2.920)

  ID 202071842 (P=4.176. Maybe additional transit at ~1969.3 BKJD)

  ID 202072451 (P=5.659)

  ID 202072932 (P=1.568)

  ID 202084447 (P=ø)

  ID 202072933 (P=3.142)

  ID 202060439 (P=0.668)

  ID 202072940 (P=1.246)

  ID 202072941 (P=12.422)

  ID 202072947 (P=1.842)

  ID 202072958 (P=2.010. Maybe interesting at BKJD 1940.73 & 1967.8)

  ID 202072959 (P=4.068)

  ID 202072961 (P=2.046)

  ID 202072962 (P=4.170. Maybe additional transit at 1969.3 BKJD)

  ID 202072963 (P=4.210)

  ID 202072965 (P=2.142)

  ID 202072966 (P=2.144)

  ID 202072971 (P=4.399. Maybe interesting at ~ 1943.05 BKJD)

  ID 202072972 (P=4.447)

  ID 202072978 (P=4.886)

  ID 202072982 (P=7.795)

  ID 202093353 (P=2.646)

  ID 202072988 (P=5.325)

  ID 202072991 (P=2.747)

  ID 202072992 (P=2.748)

  ID 202073003 (P=6.104)

  ID 202073004 (P=6.150)

  ID 202072061 (P=1.050)

  ID 202072563 (P=1.062)

  ID 202072596 (P=3.978)

  ID 202065543 (P=0.722)

  ID 202065545 (P=5.328)

  ID 202072430 (P=20.003)

  ID 202072502 (P=1.922)

  ID 202085698 (P=9.710)

  ID 202071579 (P=1.566)

  ID 202070263 (P=3.411)

  ID 202072624 (P=7.805. Maybe GDOR with EB)

  ID 202071631 (P=3.475)

  ID 202071635 (P=6.293)

  ID 202087576 (P=ø)

  ID 202071645 (P=23.742)

  ID 202071684 (P=1.327)

  ID 202071731 (P=2.739)

  ID 202062176 (P=4.348)

  ID 202068807 (P=4.237. Maybe additional transit 1941.15 BKJD)

  ID 202071505 (P=3.548. Maybe additional transits at [1955.4-1956]BKJD & 1970.15)

  ID 202065269 (P=ø)

  ID 202068686 (P=8.730)

  ID 202066699 (P=2.213)

  ID 202066394 (P=3.188)

  ID 202072881 (P=0.393)

  ID 202073434 (P=0.664)

  ID 202073438 (P=2.408)

  ID 202073440 (P=2.632)

  ID 202073445 (P=1.418)

  ID 202073476 (P=ø)

  ID 202073490 (P=1.017)

  ID 202073495 (P=2.860)

  ID 202073154 (P=?)

  ID 202073160 (P=1.412)

  ID 202073161 (P=1.404)

  ID 202073174 (P=0.644)

  ID 202073175 (P=1.280)

  ID 202073185 (P=0.613)

  ID 202073186 (P=1.224)

  ID 202073203 (P=2.4)

  ID 202073207 (P=1.050)

  ID 202073210 (P=1.025)

  ID 202073217 (P=0.941)

  ID 202073218 (P=0.920)

  ID 202073235 (P=0.820)

  ID 202073238 (P=0.791)

  ID 202073248 (P=0.757)

  ID 202073253 (P=0.367)

  ID 202073262 (P=2.250)

  ID 202073267 (P=0.683)

  ID 202073270 (P=0.659)

  ID 202073294 (P=0.558)

  ID 202073297 (P=0.529)

  ID 202074775 (P=4.031)

  ID 202067245 (P=6.163)

  ID 202066811 (P=2.4)

  ID 202064253 (P=21.126)

  ID 202062450 (P=4.455)

  ID 202083021 (P=2.936)

  ID 202083140 (P=0.363)

  ID 202083222 (P=2.3)

  ID 202083510 (P=2.3)

  ID 202083650 (P=2.457)

  ID 202083924 (P=0.568)

  ID 202084111 (P=0.752)

  ID 202084588 (P=ø)

  ID 202085014 (P=0.274)

  ID 202085183 (P=0.387)

  ID 202085278 (One transit P=ø. P=2.146 maybe pulsations)

  ID 202085432 (P=8.704)

  ID 202086223 (P=11.544)

  ID 202086225 (P=25.642)

  ID 202086291 (P=4.86)

  ID 202086627 (P=7.151)

  ID 202103762 (P=1.326)

  ID 202122545 (P=19.231)

  ID 202126825 (P=9.207)

  ID 202126851 (P=4.482)

  ID 202126853 (P=21.167. TTV!)

  ID 202126864 (P=6.188)

  ID 202126866 (P=2.336)

  ID 202126867 (P=2.416)

  ID 202126876 (P=10.354)

  ID 202126878 (P=5.577)

  ID 202126880 (P=3.459)

  ID 202126886 (P=2.941)

  ID 202126887 (P=12.833)

  ID 202135247 (P=ø. Transit duration = 39.7 h)

  ID 202136008 (P=2.125)

  ID 202136063 (P=5.205)

  ID 202136445 (P=5.723)

  ID 202137190 (P=ø)

  ID 202137571 (P=2.240)

  ID 202137580 (P=ø. 50.5 h transit duration)

  ID 202138045 (P=0.387)

  ID 202139294 (P=0.521)

  ID 202139332 (P=ø)

  Heartbeat Binaries:

  ID 202065802

  ID 202072042 (P=6.108)

  ID 202065819 (P=5.741)

  ---

  RR-Lyrae Type:

  ID 202064435

  ID 202064436

  ID 202064438

  ID 202064439

  ID 202064447

  ID 202064516

  ID 202064526

  ID 202064530

  ID 202064531

  ---

  GDOR/DSCT:

  ID 202068728

  ID 202088780

  ID 202088965

  ID 202090967

  ID 202091045

  ID 202092351

  ID 202092980

  ID 202088789

  ID 202091553

  ID 202093036

  ID 202093166

  ID 202094076

  ID 202094935

  ID 202095353

  ID 202095563

  ID 202060461

  ID 202060928

  ID 202062514

  ID 202067092

  ID 202072075

  ID 202072204

  ID 202072678

  ID 202072688

  ID 202085987

  ID 202138046

  ID 202136223

  Posted December 8, 2014 3:22 AM

• by Dolorous_Edd

  http://talk.planethunters.org/#/subjects/APH00008le?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH0000cdt

  http://talk.planethunters.org/#/subjects/APH00008mp

  http://talk.planethunters.org/#/subjects/APH00008r8

  http://talk.planethunters.org/#/subjects/APH0000c5l

  http://talk.planethunters.org/#/subjects/APH0000b2f?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH000090o?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH0000c5l

  http://talk.planethunters.org/#/subjects/APH0000a3g?quarter=0-1

  maybe glitch

  http://talk.planethunters.org/#/subjects/APH0000beh?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH0000bqf?quarter=0-1

  perhaps glitch

  http://talk.planethunters.org/#/subjects/APH0000a3e?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00008t6?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00008yp?quarter=0-1

  Huge transit

  http://talk.planethunters.org/#/subjects/APH000090l?quarter=0-1

  What is this?

  http://talk.planethunters.org/#/subjects/APH00007kc?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH0000b4q?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00008x5?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00008yk?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00007ft?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00008yr?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00008y3?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00008xe?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00008ye?quarter=0-1

  Posted December 8, 2014 7:11 AM

• by Dolorous_Edd

  EB with possible third object

  Flagged by JenniferConnors

  http://talk.planethunters.org/#/subjects/APH00008ej

  Posted December 8, 2014 8:45 AM

• by Artman40

  I have slightly unrelated question: I've noticed that when looking at Deep Space Network, I've noticed that only carrier signal (but no data) is sent back from Kepler spacecraft with NASA not telling about receiving Field 2 data. I wonder why.

  Posted December 8, 2014 8:53 AM

• by Martti_Holst_Kristiansen in response to Dolorous Edd's comment.

  @Dolorous Edd - They are already listed but I can see that PH has not added the Kepler ID yet.

  Posted December 8, 2014 9:33 AM

• by Dolorous_Edd in response to Martti Holst Kristiansen's comment.

  Yes , but without KID I can't say what is on the list what is not

  They also could be pre-surveyed and can be well known , but again I have no way to know that.

  So I will proceed

  RR-Lyrae type

  http://talk.planethunters.org/#/subjects/APH00007ks?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00007ko?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00007kx?quarter=0-1

  eb

  http://talk.planethunters.org/#/subjects/APH00008rl?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00008ql?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH000090q?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00007kw?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH0000797?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH0000790?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00008fn?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00008fn?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH0000790?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH0000b2e?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH0000bcr?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00008xw?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH0000akj?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00007oa?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00008gn?quarter=0-1

  Possible pc

  http://talk.planethunters.org/#/subjects/APH0000akf?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH0000aps?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00009dt?quarter=0-1

  Posted December 8, 2014 9:38 AM

• by Martti_Holst_Kristiansen in response to Dolorous Edd's comment.

  Of couse that is totally fine, it was not a discrimination. Good hunting.

  Posted December 8, 2014 9:55 AM

• by zoo3hans

  I think 202064436 might be a Cepheid.

  Posted December 8, 2014 2:13 PM

• by Shellface

  KID 202094740 shows shallow transit-like events every ~0.65 days.

  Posted December 8, 2014 5:22 PM

• by troyw

  Nice job Martti. Following up on your finds:

  202059360 p=3.680406 : secondary transits.(EB)

  202072704 p=2.66634 : faint secondary transits.(EB)

  202071289 p=3.0444 : faint secondary transits.(EB)

  202066537 p=6.90561

  202088212 p=2.6196

  202093353 p=2.6404 : Apeture contains 5-7 sources. Possibly contamination from an EB.

  202090723 p =6.1504

  202071828 p=4.71325 : Seems like contamination based on transit shapes.(EB?)

  202093020 p=4.13325 : Light curve dips slightly where secondary transits might occur.(EB)

  202060439 p=0.667406 : Secondary transits (EB)

  202060447 p=2.0297 : Secondary transits (EB)

  202060506 p=1.96 : Secondary transits (EB)

  202066192 p=3.2921

  202087156 p=1.895424 : alternate transits possibly indicate primary and secondary transits.

  202087501 Garbage

  202085597 p=1.8151

  202126847 p=4.1701

  202126852 p=2.7904

  202126849 p=3.8

  202085698 P=17.140812

  202083828 p=14.5608

  202084843 p=2.0344 : strange transit depth variations. (found to be contamination from a nearby target)

  202126884 p=5.3175 : Beautiful

  202137637 p=6.6195 : Gorgeous

  202137209 p=2.382618 : Faint secondary transists (EB)

  202136151 p=6.3883

  Posted December 8, 2014 9:11 PM

• by troyw

  Following up on 202093353, the EB is not the targeted star but rather the one below, and it has a faint secondary transit.

  

  

  Posted December 8, 2014 10:01 PM

• by TED91

  KID 202088178 - APH0000a7r

  Possible trinary or binary + planet

  Posted December 8, 2014 10:17 PM

• by TED91

  KID 202073043 - APH00008xx

  Nice transit

  Posted December 8, 2014 10:43 PM

• by arvintan in response to Dolorous Edd's comment.

  EPIC 202089948 http://talk.planethunters.org/#/subjects/APH0000akf?quarter=0-1

  This one looks promising. A quick search in the GO proposals says this star is an M-dwarf. Given the shallow and long transit, I think this could be a good Earth-sized or sub-Earth candidate.

  http://keplerscience.arc.nasa.gov/K2/docs/Campaigns/C0/GO0111_SanchisOjeda.pdf

  Posted December 9, 2014 7:25 AM

• by Martti_Holst_Kristiansen

  Hi Troy. Thank you for adding to the findings, it is also my plan to reevaluate the findings the next couple of days so the list become more adequate. Furthermore I intend to go through the dataset once again but this time more carefully.

  @Arvintan, that was exactly my thought. The signal depth is ~325 PPM and If i remember correctly there are 2-3 of these instances in the data set. It reminded me of an earlier PH 2.0 M-dwarf find: http://talk.planethunters.org/#/boards/BPH0000005/discussions/DPH00004ab . As I mentioned before I will revisit the findings are dig up the similar features.

  Posted December 9, 2014 10:37 AM

• by HeadAroundU

  http://talk.planethunters.org/#/subjects/APH0000bmm unlisted EB or heartbeat binary EPIC no: 202095298

  Posted December 9, 2014 4:16 PM

• by Dolorous_Edd

  EB with possible third transit

  EPIC 202072962 ( Martti it is on your list, but I don't see you mention dip @1969, sorry if anything

  http://talk.planethunters.org/#/subjects/APH00008xc?quarter=0-1

  Posted December 9, 2014 4:37 PM

• by Martti_Holst_Kristiansen in response to Dolorous Edd's comment.

  No, I have not mentioned it but unfortunately I now more than before suspect it is a glitch. The same feature is found in the following LCs:

  ID 202071842 (P=4.176. Maybe additional transit at ~1969.3 BKJD)

  ID 202072962 (P=4.170. Maybe additional transit at 1969.3 BKJD)

  Good hunting!

  EDIT: Sorry, I read your ID wrongly.

  Posted December 9, 2014 5:11 PM

• by troyw

  Taken apart from part of the superstamp, 200000811 has a possible planet with a period of 7.556 days.

  Lightcurve

  

  Posted December 9, 2014 5:25 PM

• by Dolorous_Edd

  Edit* Looks like a glitch

  Maybe just me, but maybe there is a dip every 2 days or so

  http://talk.planethunters.org/#/subjects/APH000094u?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH000083s?quarter=0-1

  http://talk.planethunters.org/#/subjects/APH00009yb?quarter=0-1

  Posted December 9, 2014 5:46 PM

• by arvintan

  EPIC 202084447 http://talk.planethunters.org/#/subjects/APH00009ho?quarter=0-1

  There's a very bright star at the upper right corner. Could be the source of this EB-like feature.

  

  Posted December 9, 2014 5:51 PM

• by Shellface

  @arvintan that star isn't within the aperture, and indeed there appears to be only one star present.

  Posted December 9, 2014 7:31 PM

• by Dolorous_Edd in response to arvintan's comment.

  The 1955.6 bjd glitch caused by Jupiter reflection

  See this paper

  Posted December 9, 2014 8:03 PM

• by Martti_Holst_Kristiansen

  @Arvintan & Shellface

  It appears in a quite a few of the LCs so it is probably a glitch (~1955.75 BKJD).

  From the paper Dolorous Edd mentioned:

  "Reflections from Jupiter also introduced artifacts in
  other modules when Jupiter exited the focal plane at
  BJD - 2454833 = 1955.75. There was a spike in the back-
  ground level in many modules, and in some cases, the
  spike was not properly removed during aperture photom-
  etry. This can lead to anomalous spikes or decrements in
  the light curves at this time."

  Posted December 9, 2014 8:03 PM

• by Dolorous_Edd in response to Martti Holst Kristiansen's comment.

  ID 202066212 (P=6.179)

  Here it is op PH (actually I think period is about 3days, likely eb contamination )

  http://talk.planethunters.org/#/subjects/APH00007vr

  Posted December 9, 2014 9:03 PM

• by HeadAroundU

  http://talk.planethunters.org/#/subjects/APH00007vk?quarter=0-1 EPIC no: 202066194 big transit, but a bit crazy around

  Posted December 10, 2014 3:43 AM

• by reptilelover1995

  http://talk.planethunters.org/#/subjects/APH00009y5
  I think there's a potential transit starting at day 5.25. Honestly I don't know anything more about how to do this type of stuff than just looking at these graphs and looking for dips so I could certainly be wrong.

  Posted December 10, 2014 6:13 AM

• by Dolorous_Edd

  On your list Martti, but worth special attention, It is (likely ) M-dwarf with probable pc ( 3 transits p=14d )

  http://talk.planethunters.org/#/subjects/APH00009dt

  http://talk.planethunters.org/#/boards/BPH0000005/discussions/DPH000074g

  Posted December 10, 2014 12:17 PM

• by Martti_Holst_Kristiansen

  @Dolorous Edd,

  Regarding ID 202066212 I think you are right there seems to be a faint secondary signal.

  Posted December 10, 2014 1:02 PM

• by Dolorous_Edd in response to Martti Holst Kristiansen's comment.

  BGEB is always a possiblity, but this one is worth a TPF analysis IMO

  Posted December 10, 2014 1:09 PM

• by Martti_Holst_Kristiansen in response to Dolorous Edd's comment.

  I Agree.

  Posted December 10, 2014 1:35 PM

• by troyw in response to Martti Holst Kristiansen's comment.

  202066212 is an intersting system. It might be a background EB, but it also appears to have large TTVs. Primary and secondary eclipses are visible with a period of ~6.15 days.

  

  Posted December 10, 2014 2:13 PM

• by ajamyajax

  202126884 does looks like the perfect planet candidate. Six nearly uniform transits in Campaign 0 that fit that way also. Hopefully it is at hot gas giant planet depth; it appears to be (assuming blending not an issue). Maybe a tiny bit of TTV, but will check that again later when more data.

  So this could be a nice K2 find as you already noticed. Maybe someone could check UKIRT and for other possible contamination later.

  My estimates; works for my chart's scale:

  s1=1940.948 p1=5.3205 d1=0.3 (7.2 hours)

  ttv1 = [1940.948,1946.27,1951.593,1956.905,1962.227,1967.55]

  

  (Updated charts)

  

  And if the TTV is real, perhaps an early MMR cycle is showing:

  

  K2 corrected light curve data credit: Vanderburg & Johnson (2014)

  Posted December 10, 2014 3:04 PM

• by Dolorous_Edd in response to ajamyajax's comment.

  Can offer only DSS image

  

  N | Cat | ID/Name | RA/Lon | Dec/Lat | X | Y

  1 | http://archive.stsci.edu/k2/epic/search.php | 202126884 | 96.6792| 25.2050| 150.0| 150.0

  2 | http://archive.stsci.edu/k2/epic/search.php | 209485162 | 96.6821| 25.2026| 102.5| 106.8

  3 | http://archive.stsci.edu/k2/epic/search.php | 209486362 | 96.6760| 25.2076| 201.4| 196.8

  4 | http://archive.stsci.edu/k2/epic/search.php | 209484953 | 96.6849| 25.2017| 57.4| 90.5

  5 | http://archive.stsci.edu/k2/epic/search.php | 209486347 | 96.6863| 25.2075| 33.5| 196.1

  6 | http://archive.stsci.edu/k2/epic/search.php | 209486182 | 96.6717| 25.2068| 271.0| 182.9

  7 | http://archive.stsci.edu/k2/epic/search.php | 209483849 | 96.6814| 25.1967| 113.4| 2.2

  8 | http://archive.stsci.edu/k2/epic/search.php | 209487606 | 96.6837| 25.2130| 77.3| 295.1

  9 | http://archive.stsci.edu/k2/epic/search.php | 209484418 | 96.6705| 25.1994| 291.1| 49.3

  10 | http://archive.stsci.edu/k2/epic/search.php | 209487191 | 96.6708| 25.2112| 285.8| 262.4

  Posted December 10, 2014 4:47 PM

• by HeadAroundU

  http://talk.planethunters.org/#/subjects/APH00007wy?quarter=0-1 4 dots transit at 32.3 not listed EPIC no: 202066523

  Posted December 10, 2014 4:55 PM

• by Martti_Holst_Kristiansen

  Are there anyone who are able to identifying nearby stars using SkyView? I can not get SkyView to respond properly.

  I have made the following changes:

  In Catalog Overlays I changed Vizier Catalog or Catalog URL to: http://archive.stsci.edu/k2/epic/search.php and tried DSS and DSS2 Red in Optical:DSS:.

  Posted December 10, 2014 4:59 PM

• by Martti_Holst_Kristiansen

  @Dolorous Edd - What kind of changes did you implement to get SkyView to respond?

  Posted December 10, 2014 5:54 PM

• by arvintan

  EPIC 202085859 http://talk.planethunters.org/#/subjects/APH00009rt?quarter=0-1

  Looks like a cataclysmic variable. Could be the bright star (#92) at bottom left.

  

  Posted December 10, 2014 6:22 PM

• by Dolorous_Edd

  One more thing EPIC 202126884

  is GO0116_LC

  HIGH PRIORITY HATNET TRANSITING PLANET CANDIDATES AND ECLIPSING BINARIES IN THE K2 CAMPAIGN 0 FIELD

  http://keplerscience.arc.nasa.gov/K2/docs/Campaigns/C0/GO0116_Bakos.pdf

  Posted December 10, 2014 7:05 PM

• by Dolorous_Edd

  EPIC 202091388

  http://talk.planethunters.org/#/boards/BPH0000005/discussions/DPH00007f4

  Posted December 10, 2014 7:22 PM

• by Shellface in response to Dolorous Edd's comment.

  On a related note: EPID 202126849 is HAT-P-54b. That's why the transits are so deep.

  Posted December 10, 2014 8:04 PM

• by Shellface in response to ajamyajax's comment.

  EPID 202126884: This is (probably) that star in SIMBAD. Its B-V of 0.52 ± 0.35 very loosely constrains its spectral type to F7 (K1 - A6). I don't know how to calculate a/R* from transit duration + orbital period, but comparisons with validated candidates suggest a radius of ~1.5 - 2 Rsol for somewhat lower stellar masses, so I suggest that the star is a moderately evolved mid-late F star. The companion radius is something like 1.4 Rjup, which is quite normal for an irradiated Hot Jupiter. There is only one star in the aperture, so I posit that this is a strong HJ candidate.

  With all this in mind, I must point out that the out-of-transit variations (see above link) for this star are noteworthy. Their nature is fairly consistent-looking with being caused by a planet (where minimum light times occur at transit and eclipse, respectively) or at least a faint object, but they are obviously extremely asymmetric, with secondary minimum occuring about a day after phase 0.5. This naively suggests that the companion has a considerable eccentricity, which is both concerning and potentially most interesting.

  (Oh yeah, and you said "will check that again later when more data". You do know that K2 observes a different field with every campgaign, right?)

  Posted December 10, 2014 8:50 PM

• by ajamyajax in response to Shellface's comment.

  A HJ then is hopeful. And maybe HJ eccentricity is less common but more interesting?

  "A paucity of proto-hot Jupiters on super-eccentric orbits"

  Rebekah I. Dawson, Ruth A. Murray-Clay, John Asher Johnson

  http://arxiv.org/abs/1211.0554

  Re: (Oh yeah, and you said "will check that again later when more data". You do know that K2 observes a different field with every campgaign, right?)

  I do now, so scratch the follow-up idea I suppose.

  Posted December 10, 2014 11:45 PM

• by ajamyajax

  Regarding EPIC 202137637:

  Even though this transit shows a bit of flattening, my guess is the 2%+ drop in brightness means this one is likely a binary.

  s1=1944.574 p1=6.6197 d1=0.35 (8.4 hours)

  

  K2 corrected light curve data credit: Vanderburg & Johnson (2014)

  Posted December 10, 2014 11:51 PM

• by Shellface in response to ajamyajax's comment.

  EPID 202137637: After some finagling (who knew there was a 2MASS point source archive?), I've managed to retrieve the colours for this source, which indicate a mid-K spectral type. So the deep transits are acceptable (remember that transit depth is inversely correlated with stellar radius), but what's less good is that there are three stars in the aperture.

  Posted December 11, 2014 1:23 AM

• by andrew418

  Hi all,

  I can confirm that for ep202137637, the eclipses are originating from the brightest star within the aperture (the central star). The dips are about 3.7% when you don't have dilution from the other sources nearby.

  Best,
  Andrew

  Posted December 11, 2014 1:42 AM

• by Shellface in response to ajamyajax's comment.

  Yes, eccentric Hot Jupiters are rather rare, which makes it more likely that this is a false positive. Nevertheless, that will require follow-up to determine for certain.

  As for your TTV diagram, you must remember that any telescope has finite precision, and random scatter can look like pretty much anything in a small dataset. The noise floor for K2 TTVs is likely a few minutes, so I expect that this is a null result.

  (Also, I notice you're still using that odd/even transit profile. While that's not a bad thing, I do think that that the diagram style with different colours for each transit is more relevant for "normal" cases)

  Finally, using this 2MASS catalog I've gained a far better estimate of the star's spectral type: G0 ± 1. This seems consistent with my previous result except that the star is slightly more evolved (and hence, cooler).

  Posted December 11, 2014 1:52 AM

• by Shellface in response to andrew418's comment.

  Thanks for that. Although that is now a very large transit depth, because of the star's late spectral type it surprisingly only implies a radius of ~1.1 Rjup, which is quite consistent with a planet. Although the host is extremely faint, this seems like it's suitable for follow-up due to the large RV amplitude such a planet would induce.

  Posted December 11, 2014 2:03 AM

• by Shellface in response to Shellface's comment.

  (Hey, I can respond to myself!)

  EPID 202094740: This star's colours give a spectral type of ~F5, so the transit depth of ~0.5% gives a companion radius of ~1 Rjup assuming the star is approximately main sequence. The irregular transit depths seem excusable to to the cadence of observations, but I suspect that the transit lengths are too short for the orbital period; there are two stars in aperture, so maybe this is a blend?

  aja, could you take a look at this one with odd/even modelling? The S/N isn't great, but it should be able to determine whether the transits are different.

  Posted December 11, 2014 2:24 AM

• by andrew418

  For ep202094740, it appears that the signal is originating from the brighter blob within the aperture, if there are in fact two stars. I actually think for this one though, that there is only one star in the aperture, and that the PSF just looks wonky because it's on one of Kepler's outer CCD modules. If the apertures are not circular, they trace out the shape of the Kepler PSF at that location on the field of view, and the aperture seems to fit the bright elongated blob quite nicely. Of course, the way to check for sure that there are no other stars would be to look at some archival imaging.

  Best,
  Andrew

  Posted December 11, 2014 2:55 AM

• by ajamyajax in response to Shellface's comment.

  Re: (Also, I notice you're still using that odd/even transit profile. While that's not a bad thing, I do think that that the diagram style with different colours for each transit is more relevant for "normal" cases)

  No problem/will do, that's usually my default option anyway. Just eb-centric at the moment.

  Posted December 11, 2014 3:01 AM

• by ajamyajax in response to Shellface's comment.

  Re: "could you take a look at this one with odd/even modelling?"

  202094740 already on my list actually. But looks like TTV there, so have to inspect each transit which takes time at P=~0.65 or so. But I'll try to work on that one starting tomorrow.

  Posted December 11, 2014 3:04 AM

• by ajamyajax in response to andrew418's comment.

  BTW Andrew, it's great to have your help here. Thank you so much. I still need to look at your diagnostic files and (hopefully) work those into this process.

  Posted December 11, 2014 3:07 AM

• by andrew418

  No problem, this is exciting! I'm glad to be able to help.

  Posted December 11, 2014 5:15 AM

• by Dolorous_Edd

  EPIC 202126884

  On the PH

  http://talk.planethunters.org/#/subjects/APH0000br3

  Posted December 11, 2014 6:39 AM

• by alschmitt in response to ajamyajax's comment.

  For 202094740, the periodicity checker in LcViewer shows Epoch 1 located at 1939.43 BKJD, a transit duration of 2.45 Hrs, and a period of 0.689 days. I don't see any significant TTVs. There appears to be some variability in the transit duration but accurate readings are being mitigated by numerous time gaps and dropouts.

  
  

  Posted December 11, 2014 12:14 PM

• by Dolorous_Edd

  Another one from the list

  http://talk.planethunters.org/#/subjects/APH00008jn

  Listed under GO0100 PROBING THE PLANETARY POPULATION OF HIGH-MASS STARS

  http://keplerscience.arc.nasa.gov/K2/docs/Campaigns/C0/GO0100_Johnson.pdf

  Seems to be only one star within optimal aperture, maybe good

  https://www.cfa.harvard.edu/~avanderb/k2c0/ep202071690.html

  Posted December 11, 2014 1:46 PM

• by Dolorous_Edd

  Thoughts about 202093107?

  http://talk.planethunters.org/#/subjects/APH0000b70?quarter=0-1

  Posted December 11, 2014 2:06 PM

• by Dolorous_Edd

  For 202094740

  

  Posted December 11, 2014 2:58 PM

• by Martti_Holst_Kristiansen in response to Dolorous Edd's comment.

  The informations:

  N | Cat | ID/Name | RA/Lon | Dec/Lat | X | Y

  1 | http://archive.stsci.edu/k2/epic/search.php | 202094740 | 100.4631| 27.0972| 150.0| 150.0

  2 | http://archive.stsci.edu/k2/epic/search.php | 209880251 | 100.4695| 27.0954| 47.9| 117.8

  3 | http://archive.stsci.edu/k2/epic/search.php | 209879460 | 100.4720| 27.0906| 8.8| 31.7

  Posted December 11, 2014 3:17 PM

• by HeadAroundU

  http://talk.planethunters.org/#/subjects/APH0000avf?quarter=0-1 unlisted strange eb

  Posted December 11, 2014 4:43 PM

• by Dolorous_Edd in response to HeadAroundU's comment.

  Likely an artifact

  https://www.cfa.harvard.edu/~avanderb/k2c0/ep202091456.html

  Posted December 11, 2014 6:28 PM

• by ajamyajax in response to alschmitt's comment.

  Well, the sparse data makes 202094740 a judgment call, in my opinion. My first transit fit shown has no TTV adjustment, the second with the undersampling effect has my observations for possible TTV. And the related odd/even O-C plot might show some anti-correlation between two objects. And both fits are similar and V-shaped, in a faint transit/blended LC kind of way. (Edit: my duration could be a bit less, more causes the fit lines to get a bit wobbly.)

  s1=1939.4363 p1=0.68974 p1=0.15 (2.52 hours)

  ttv = [1939.4363,1940.131,1940.825,1941.4998,1942.1948,1942.8793,1943.5737,1944.2574,1944.9527,1945.6482,1946.332,1947.0265,1947.716,1948.4057,1949.1005,1949.785,1950.4693,1951.1638,1951.8588,1952.5434,1953.2276,1953.9224,1954.6173,1955.3114,1955.986,1956.6806,1957.355,1958.07,1958.754,1959.439,1960.134,1960.818,1961.513,1962.187,1962.892,1963.576,1964.2606,1964.965,1965.64,1966.3343,1967.0293,1967.7137,1968.408,1969.0925,1969.7873,1970.4717,1971.167,1971.8512]

  
  
  

  K2 corrected light curve data credit: Vanderburg & Johnson (2014)

  Posted December 11, 2014 8:17 PM

• by HeadAroundU

  http://talk.planethunters.org/#/subjects/APH00007vl?quarter=0-1 31 32.5

  Posted December 12, 2014 1:37 AM

• by zoo3hans

  KID 202126887 has 3 fine transits. Transit depth about 0.027. It could be a warm Jupiter. with a period around 12.9 days.

  http://talk.planethunters.org/#/subjects/APH0000br5
  .

  Posted December 12, 2014 6:20 AM

• by Martti_Holst_Kristiansen in response to zoo3hans's comment.

  Image plot (Vanderburg & Johnson (2014)):

  

  The Skyview image shows three stars within the photometric aperture.

  

  N | Cat | ID/Name | RA/Lon | Dec/Lat | X | Y

  1 | http://archive.stsci.edu/k2/epic/search.php | 202126887 | 99.3805| 26.7866| 200.0| 200.0

  2 | http://archive.stsci.edu/k2/epic/search.php | 209822549 | 99.3808| 26.7880| 194.3| 233.9

  3 | http://archive.stsci.edu/k2/epic/search.php | 209822013 | 99.3822| 26.7851| 165.2| 166.3

  4 | http://archive.stsci.edu/k2/epic/search.php | 209821375 | 99.3742| 26.7819| 335.3| 89.6

  5 | http://archive.stsci.edu/k2/epic/search.php | 209823286 | 99.3868| 26.7920| 66.8| 329.5

  Posted December 12, 2014 10:31 AM

• by ajamyajax in response to zoo3hans's comment.

  Well, unfortunately more sparse transit data with this LC (202126887) so my period could be a little +/-. Good luck.

  s1=1944.2375 p1=12.867 d1=0.12 (2.88 hours)

  

  K2 corrected light curve data credit: Vanderburg & Johnson (2014)

  Posted December 12, 2014 2:27 PM

• by troyw

  202126887

  Posted December 12, 2014 3:12 PM

• by Dolorous_Edd

  Can somebody explain why do we even bother with GO0116 ?? Is there anything to gain for PH???

  HIGH PRIORITY HATNET TRANSITING PLANET CANDIDATES AND ECLIPSING BINARIES IN THE K2 CAMPAIGN 0 FIELD

  Even the name of this GO implies that

  a) They choose them deliberately ( previously detected by The HATNet project )

  b) Authors of this proposal are well aware about these cadidates

  Posted December 12, 2014 3:28 PM

• by mschwamb scientist in response to Dolorous Edd's comment.

  You can read the proposal and see what they say. I believe the point is to actually get good planet characteristics. Ground-based transit surveys have huge photometric blends. So Kepler is ground truth for their search algorithms and candidate confidence. They can also look for smaller companion planets in the system as well as other planets in the system both transiting and through transiting timing variations (TTVs). You can find all the successful proposals for Campaign 0 here.

  Cheers,

  ~Meg

  Posted December 12, 2014 3:51 PM

• by ajamyajax in response to Dolorous Edd's comment.

  Yeah, if a transit is obvious to the experienced eye you probably can assume a number of professionals have already seen it. I do anyway. If this cheers you up, I also contribute to the Kepler community follow-up program (cfop). As an amateur I use my computer skills to help them identify false positives on the KOI list and so forth. And I believe I have helped there -- at times. But even though there are a number of professional astronomers who already know about these objects, the best planet candidates still aren’t confirmed as planets until a thorough study is made, a paper is written, and then reviewed. And if all goes well it is then accepted and published. That has happened at Planet Hunters for K1 and could again for K2 and beyond in my view. But how patient you are with that process is entirely up to you.

  Posted December 12, 2014 5:49 PM

• by ajamyajax

  202072704 looks like a pretty good planet candidate in my view. Sure seems close enough to be a hot gas giant at p=2.6673. More sparse data and a little less uniform in appearance, but maybe there is a reason for that. Also maybe there is TTV in the LC but fwiw, my fits look similar regardless.

  s1=1941.2961 p1=2.6673 d1=0.145 (3.48 hours)

  ttv1 = [1941.2961,1943.962,1946.629,1949.295,1951.9715,1954.6275,1957.294,1959.96,1962.6365,1965.303,1967.9695,1970.6253]

  

  K2 corrected light curve data credit: Vanderburg & Johnson (2014)

  Posted December 12, 2014 5:54 PM

• by Dolorous_Edd in response to ajamyajax's comment.

  Listed under GO0100

  PROBING THE PLANETARY POPULATION OF HIGH-MASS STARS

  SkyView DSS2

  

  N | Cat | ID/Name | RA/Lon | Dec/Lat | X | Y

  1 | http://archive.stsci.edu/k2/epic/search.php | 202072704 | 101.4626| 17.2069| 200.0| 200.0

  2 | http://archive.stsci.edu/k2/epic/search.php | 207485065 | 101.4657| 17.2043| 127.8| 137.9

  3 | http://archive.stsci.edu/k2/epic/search.php | 207486119 | 101.4562| 17.2088| 346.0| 243.6

  See also

  https://www.cfa.harvard.edu/~avanderb/k2c0/ep202072704.html

  Seems like only one star within aperture

  Posted December 12, 2014 6:11 PM

• by troyw

  I like looking at previously known objects in the new K2 data to get a sense of comparison to what is known vs what is seen in the new data. This helps (me) to determine what needs to be done to calibrate my own algorithms.

  There is also HD 50554b in the C0 data. The mask for that one is 29x394 pixels! However, I believe that is not included in the release of these lightcurves (EPIC202061312).

  There are 2 short period candidates already known that are in the C1 field as well (WASP 85b and HD 102195b).

  Posted December 12, 2014 6:18 PM

• by Shellface in response to Shellface's comment.

  I skip a day and there's three new pages. Criminy.

  To conclude with EPID 202094740:

  • Andrew, thanks for pointing that out. The 2MASS image for the source shows only one bright star (and one extremely faint one), so blending is now considerably less likely.

  • Al, aja, nice work. I see that the odd/even transits are not significantly different, and that transit length is actually reasonably consistent with the expected value, so I think it's reasonable to consider this a (rather extreme) planet candidate. As for those TTVs, when treating this as one-object the transit times are never much more than 1σ apart.

  A transit depth of 0.34% gives a radius ratio of ~0.0525, so for a stellar radius of ~1.5 Rsol the companion radius is ~0.8 Rjup. For sensible values of companion mass, the planet candidate's radius fills a significant amount of its roche lobe, but is at little risk of overflowing it. Given the star's nature as a tidally inefficient star (mid-F, probably dwarf) such a companion would have lesser risk of being accreted due to period loss.

  This does seem like a valid candidate, although it falls into a region of the period-radius diagram that is completely empty. It would be fairly easy to verify or disprove; the star is reasonably bright, fairly amenable for RV measurements, and has a short period.

  Posted December 12, 2014 11:14 PM

• by Shellface in response to zoo3hans's comment.

  EPID 202126887: This star's colours are G0, so the transit depth implies a companion radius of ~1.7 Rjup, which is very large considering the decreased insolation relative to typical HJs. The transit length is also considerably shorter than it should be, so I suspect this is a blended EB where the primary is a small star.

  Posted December 12, 2014 11:24 PM

• by Shellface in response to ajamyajax's comment.

  EPID 202072704: Colours are indicative of late-A spectral type. Radius ratio is approximately 0.072 and the transits indicate the star is high-density (dwarf), so for a stellar radius of ~1.6 Rsol the companion radius is ~1.15 Rjup.

  I agree that this is a good planet candidate, but its early spectral type makes conventional follow-up with RVs difficult. However, I expect its phase curve has strong potential to determine the mass of the companion:

  

  I'm not too familiar with how that would be done, but I expect it requires some knowledge of the planet's temperature. That can be found by measuring its eclipse depth; optimistically, that may be possible with this data as the symmetricity of the phase curve implies the companion's eccentricity is ~0 so the eclipse should occur at phase 0 on the above diagram, or half an orbit from a transit.

  aja, do you think you can try this? Something like "find the observations halfway from a transit (within, say, 3 hours either side of phase 0), then fit a transit with the same length as the actual one". It will be very shallow and possibly undetectable, but an upper limit would at least give an upper limit to the companion's temperature, and thus some constraint on its mass. Possibly.

  Posted December 13, 2014 12:13 AM

• by andrew418

  You're right -- you can estimate the mass of the companion through the phase curve using what is called the BEER technique -- which lets you measure the star's mass in two different ways (one through special relativity, and one through the distortion of the host star due to the companion's gravity). Equations describing these effects and how to estimate the mass are given on page 4 of this paper (equation 1,2,and 3): http://arxiv.org/abs/1106.2713

  Taking a quick look at that light curve, I estimate the amplitude of the ellipsoidal variations (the sine with half the orbital period) is about 0.0005, and using equation 2 estimate about 130 jupiter masses, consistent with a late M-dwarf.

  Best,
  Andrew

  Posted December 13, 2014 1:00 AM

• by Shellface in response to andrew418's comment.

  Thanks for the reference. I believe that what you did is oversimplified (the two other effects are probably not negligible), but comparing it to other identifications of phase variations does show that this one is about an order of magnitude larger than normal ones, so the companion is probably massive. I am toying with the idea that the companion is a BD (which is more consistent with its estimated radius), but I'll get to that properly tomorrow.

  Posted December 13, 2014 2:25 AM

• by ajamyajax

  Might be a little above my pay grade : ), but I'll look into BEER etc. Will post if I come up with anything.

  Also, was my luminous companion reference correct about brown dwarfs, i.e. might we detect such candidates here by examining minimal flux dimming with more v-shaped transits? Martti posted a bunch of those I think to start this list. Of course can at least look for possible bgeb's there also.

  Posted December 13, 2014 1:30 PM

• by ajamyajax

  202126888 is potentially interesting as a candidate for a larger small companion of some type. Note in the second odd/even plot I removed the possible outliers seen below the first plot's curve fit. Those did have a small but noticeable effect; made it look slightly more like a bgeb before. But not sure if convincing enough for that. Edit: can always post the unmodified odd/even chart if interested.

  s1=1940.478 p1=1.8459 d1=0.13 (3.12 hours)

  
  

  K2 corrected light curve data credit: Vanderburg & Johnson (2014)

  Posted December 13, 2014 3:32 PM

• by Shellface in response to ajamyajax's comment.

  Aww, you gonna make little ol' me do the work… with excel? (@_@)

  Well, I did! EPID 202072704…, uh, b? has a detectable secondary transit:

  

  The eclipse has a depth of ~150 ppm, which is comparable to that of Kepler-13b; given that this object has a lower insolation than Kepler-13b, it must have a higher albedo. The eclipse is also late by about 0.02 periods (~1.3 hours), so the companion appears to be slightly eccentric.

  Anyway, I'll need a few… several hours looking at literature to try to figure out how to use this information.

  Posted December 13, 2014 7:19 PM

• by ajamyajax

  Re 202084843: well not as interesting as an albedo effect, but maybe a short-period bgeb could explain what was spotted earlier in this thread. And maybe contamination or blending could explain the transit depth variations.

  s1=1941.01 p1=2.035 d1=0.20 (4.8 hours)

  s2=1942.027 p2=2.035 d2=0.20 (4.8 hours)

  

  Update: I did look for possible co-orbitals here, but couldn't line up similar transit depths. But will keep looking. Also wondered about a possible diagnostic issue, but only because of all the variations seen here.

  Posted December 14, 2014 3:37 AM

• by ajamyajax in response to ajamyajax's comment.

  Martti, Dorlorous, et.al.

  I think 202126888 is the last of the repeating transits from your lists that looked possibly planetary in appearance -- to me anyway. The rest are v-shaped or stellar in appearance I thought. So unless you guys mention others I missed, 202126888 is the last of my fitted charts for this thread anyway. But hopefully others will pitch in here and elsewhere of course! Best of luck, as always. Mark

  p.s. also not much I can do with single transit events chart-wise.

  Posted December 14, 2014 1:49 PM

• by Martti_Holst_Kristiansen

  Mark, thank you for all your contributions I am always enjoying your comments. Best of luck to you too.

  By the way, I also love your charts!

  Posted December 14, 2014 6:31 PM

• by troyw in response to ajamyajax's comment.

  I think this is definitely contamination. An extracted curve from a target to the left (inside the red box) shows more consistent eclipses. The light curve on PH is extracted from the area inside the green. Because of the telescopes jitter, that target comes into the target pixels view every so often creating the deeper eclipses. p = 2.0345

  

  Posted December 14, 2014 11:48 PM

• by ajamyajax in response to troyw's comment.

  Awesome K2 work, Troy. Wonder if there are other telescope jitter LC's on Martti's EB list? I might also take a spin through those to find out.

  Posted December 15, 2014 2:03 PM

• by DZM admin

  All of these awesome graphs and deductions are wayyyy above my scientific pay grade, but they are fascinating to look at and read through.

  Huge props to everyone doing planet-hunting work on the K2 data!

  Posted December 15, 2014 3:21 PM

• by troyw in response to ajamyajax's comment.

  202072704 has a very faint set of secondary eclipses. If this is a planet, this must be the albedo effect you mentioned earlier. It also has a slightly eccentric orbit.

  

  Posted December 15, 2014 3:57 PM

• by Martti_Holst_Kristiansen in response to troyw's comment.

  Thanks for taking a look Troy I was also wondering about this LC, great work!

  SkyView shows four stars outside the photometric aperture:

  Image Size (degrees): 0.0167.

  

  Posted December 15, 2014 10:38 PM

• by Shellface in response to Shellface's comment.

  Alright, I did… something. It's not a fully analytical result, it isn't iterative, and it has a bunch of caveats, but I have a mass for the companion!

  First, the centre of the eclipse occurs at φ = 0.520 ± ~0.005. Using the equation

  e cos ω = π · (φ-0.5)/(1+cosec²(i)), where φ here is the location of the eclipse and i is approximated as 90°

  , the eccentricity of the companion times the cosine of its argument of periastron (which is unknown) is 0.031 ± 0.007, ignoring the contribution of the inclination of the companion.

  Below is an illustrative fit to the phase curve and its residuals. They aren't constrained by the actual physics that cause them, and the eclipse is edited in, but they're still useful.

  
  

  The grey line in the O-C diagram shows the displacement from the curve caused by the eclipse, which gives an eclipse depth of 108 (± ~25) ppm.

  The phase variations are visibly asymmetric; though we'll get to the amplitudes later, the useful parts here are the times of maxima. If we define t0 as the time of transit, t2 as the time of eclipse, and t1/t3 as the times of maximum displacement perpendicular to the line of sight, then t1 ≈ 0.23 (early) and t3 ≈ 0.76 (late). Orbital fits that satisfy all four times of extrema give ω ≈ 50°, and thus e ≈ 0.048. I estimate a/R to be 5.466 (not from the lightcurve; I haven't figured out how to derive a/R from transit length yet), and with the eccentricity information the separations (s) at different points in the orbit can be derived:

  At t0, s/R is ~5.244; at t1, it is ~5.309, at t2 it is ~5.667, and at t3 it is ~5.646.

  The eclipse (not transit) depth of a companion follows the equation

  d = Ag(r/a)² = Ag((r/R)/(a/R))², where d is the eclipse depth in zeroeth units and Ag is the geometric albedo for the companion

  . Inputting an eclipse depth of 0.000108, a radius ratio of 0.072 (approximately correct) and an a/R of 5.466 (note that I don't use s/R because it is unlikely that the companion's insolation is directly proportional to its luminosity, and using a/R applies for the mean insolation) gives a geometric albedo of 0.62. This is rather high. The equilibrium temperature of a companion is given by the equation

  Teq = T* · (1/(a/R))^0.5 · [f(1-Ab)]^0.25, where T* is the is the effective temperature of the star, Ab is the bond albedo, which is 1.5 · Ag, and f is the flux parameter, which is bracketed by the extreme values of 1/4 (complete heat redistribution) and 2/3 (no heat redistribution), and the real value is somewhere between. Given T* = 7600 K (which is a plausible value, given the colours), the Teq interval for the companion is 1180 ≤ Teq ≤ 1510 K, which is so low due to the high albedo of the object.

  For a companion with zero nightside luminosity, the semi-amplitude of the phase variations due to reflected light (aref) is Ag(r/a)² sin i, or d sin i. Since i is being approximated as 90° here, aref = d. Inputting the expected parameters for the wave results in the following residuals diagram for the phase curve:

  

  This looks surprisingly similar to phase curve with only ellipsoidal variations, considering the companion probably has a nightside luminosity and the beaming effect is not accounted for. This likely reflects issues with my rather non-dynamic modelling process, but it is not something easily addressed.

  Since both ellipsoidal variations and doppler boosting are related to the same parameter (companion mass), it is not possible to account for them independently without first finding the mass of the companion, which would require accounting for both effects. However, as the ellipsoidal variations are expected to be a factor of a few larger than the beaming effect, and as the lightcurve is visibly consistent with ellipsoidal variations, I decided to make a very approximate model with only ellipsoidal variations (aellip) being accounted for. This will give an approximately correct mass for the companion.

  The equation for calculating the semi-amplitude of ellipsoidal variations due to a companion is:

  aellip = k·m/M · (1/(a/R))³, where aellip is in zeroeth units, and k relates to the limb darkening and gravitational darkening of the primary that, for this star, comes out to ~1.06.

  Because this companion is eccentric, the shape of the primary is different at t1 than it is at t3. This can be accounted for by replacing a/R with s/R and using different semi-amplitudes and values for s/R for the two times of extrema. For t1, aellip ≈ 0.000354 and s/R ≈ 5.309, so m/M is ~0.0500. For t3, aellip ≈ 0.000275 and s/R ≈ 5.646, so m/M is ~0.0467. M is about 1.8 Msol, so the average mass ratio (~0.0483) results in a companion mass of 0.087 Msol, or 91 Mjup. This is slightly above the minimum mass limit for hydrogen fusion, so the companion probably is a very low-mass star.

  R (the primary's radius) is also about 1.8 Rsol. With a radius ratio of ~0.072, the companion radius is ~0.13 Rsol, or ~1.3 Rjup. Given plausible error bounds, this is mildly consistent with the theoretical mass-radius relationship (ex. figure 9 of Nefs et al. (2013)). It does lie above it, which is perhaps to be expected due to the star being so close to an A-dwarf.

  Even with my rather shaky analysis, the derived mass is sensible. The companion is probably not a brown dwarf due to its high albedo (something BDs are not exactly characterised by), which likely represents influence by the star's own luminosity. It also cannot have a much higher mass due to the constraint of its radius, which implies a mass of less than ~0.11 Msol.

  Anyway, there are a lot of caveats and identifiable issues with what I've done here, but it seems like a reasonable result. A far more iterative analysis (similar to the one that confirmed Kepler-91b) is desirable. All that aside, this is one bizarre system - I can't think of any other binaries with that small of a mass ratio, and there are few comparable very low-mass stars with large exterior insolations. This system could be a value case of a highly irradiated star close to the hydrogen fusion limit.

  Posted December 18, 2014 1:24 AM

• by ajamyajax

  SF: impressive work by you, and a serious effort! That much is obvious even to this novice (me). But just for argument's sake and with only the concept from a professional's paper or two to back it up: if the hot Jupiter Kepler-7B is said to have a high albedo, couldn't 202072704's companion be like that also? I mean if you are right, other HJ's might have to be revisited and revised (perhaps).

  "THE HIGH ALBEDO OF THE HOT JUPITER KEPLER-7B"

  http://arxiv.org/abs/1105.5143

  And obviously not a scientific survey, but here is one more:

  "SOPHIE velocimetry of Kepler transit candidates IV. KOI-196b: a non-inflated hot-Jupiter with a high albedo"

  http://arxiv.org/abs/1108.0550

  But again, very impressive. Also seems like you could make a highly accurate guess of the mass and radii now for many of these systems right? Whew, and a proper salute!

  p.s. And neat and tidy charts by you as well. Please add an EPIC/KIC EPID/KID (or whatever) designation title also if you don't mind. 😃

  Posted December 18, 2014 3:17 AM

• by Shellface in response to ajamyajax's comment.

  Thanks! I spent several nights trying to get the calculations to work, and though my result is not exactly the most favourable one, it's still meaningful.

  …if the hot Jupiter Kepler-7B is said to have a high albedo, couldn't 202072704's companion be like that also?

  I'm not really sure what you're trying to say - The relevant equation gives a very high albedo for the companion, but that isn't strictly meaningful because it appears to be a star, and giving an albedo for a luminous object is a strange concept.

  I mean if you are right, other HJ's might have to be revisited and revised (perhaps).

  Again, I don't follow - the calculation for albedo I used here is the same (without a few non-necessary terms) as the ones used in both of those papers.

  Also seems like you could make a highly accurate guess of the mass and radii now for many of these systems right?

  Companion radius is pretty easy to estimate, as I'm sure I don't need to tell you. As for masses, that would require detection of ellipsoidal variations (and/or beaming too, but the latter is generally smaller than the former), which become small for separations of more than a few stellar radii and for decreasing companion masses. However, I suppose - given the fairly good K2 precision that you can observe from the above diagrams - non-detections could place fairly meaningful upper limits to companion mass and albedo for Hot Jupiter systems. But, the proof is in the pudding, and I would need some strong HJ candidates first. I guess I can try starting with HAT-P-54?

  Please add an EPIC/KIC EPID/KID (or whatever) designation title also if you don't mind.

  Eh, seems a little redundant, no? If the target name has already been stated, showing it excessively doesn't add much to the work as a whole.

  Posted December 18, 2014 9:02 PM

• by andrew418

  Very nice! Those are some great looking fits.

  Here's a good reference for measuring a/R* from the light curve -- see equation 8: http://arxiv.org/abs/astro-ph/0206228

  It's pretty messy, and assumes infinitely short integration times (which is not true for Kepler), so it's sometimes a bit tricky to estimate without actually fitting the light curve and modeling the integration time.

  Best,
  Andrew

  Posted December 19, 2014 1:29 AM

• by Artman40

  I have a question: has the photometric precision improved on K2 data?

  Posted December 19, 2014 10:02 AM

• by Dolorous_Edd

  Does anyone have comments about EPIC 202088178?

  IMO it has weird sets of "transits", they are strange, period of these dips seems to be from 1.8 to 2.8 d , and they occur before and after primary eclipse

  http://talk.planethunters.org/#/subjects/APH0000a7r

  

  Few stars within optimal apperture, so maybe we are dealing with possible blend here

  https://www.cfa.harvard.edu/~avanderb/k2c0/ep202088178.html

  Posted December 19, 2014 11:18 AM

• by troyw in response to Dolorous Edd's comment.

  Looks like a blend. There's a set of transits with a period of 0.4947.

  202088178

  Posted December 19, 2014 12:16 PM

• by JKD

  202062604
  potential transit at 1958.76 BKJD with TD (transit duration) ~0.276d

  Posted December 19, 2014 8:04 PM

• by Shellface

  @andrew418: Ah, that's the kind of glossary of equations I've been needing! Before a few months ago I had only ever concerned myself with RVs, so even if I was up to date with transit literature, I had essentially no knowledge of the useful equations.

  @artman40: Compared to what? The lightcurve reduction used across Planet Hunters is perhaps an order of magnitude more precise (or, rather, more stable) than the raw data. Compared to Kepler, the reduced K2 data is perhaps 4 times less precise for typical brightnesses, though the ratio gets worse for fainter stars.

  @JKD: That is at the same amplitude as the stochastic variation in the lightcurve. It's probably a random congregation of ~8 datapoints at around the same flux.

  Posted December 19, 2014 10:05 PM

• by Artman40

  Oh...I also have a question: how good is photometric precision for brightest K2 stars observed by Kepler spacecraft (in ppm)?

  Posted December 20, 2014 5:47 AM

• by JKD

  ID 202064549 = #EB with p=9.827d plus an additional transit at 1942.38 BKJD with transit duration TD=0.2d and delta Flux ~0.00258

  Posted December 20, 2014 9:20 PM

• by Shellface

  @artman40: It's difficult to place an exact value on that, but for Kp = 8-9 (the brightest stars in the campaign 0 field) the best precision seems to be about 30 ppm. If we say that a transit needs to be 3 times deeper than the random scatter to be confidently detectable (i.e 90 ppm), then that corresponds to a companion radius of about 1 Rearth.

  @JKD: I take it you are referring to this:

  

  The "ingress" is noticeably poor and the two missing datapoints just before the centre don't help. I also recall this time in the set being glitch-prone, and I would be cautious in considering this an astrophysical event. On the upside, the event duration is approximately compatible with the critical period (minimum stable period) for a 10-day binary, and the Kepler circumbinary planets show a pile-up just outside the critical period.

  Posted December 20, 2014 10:00 PM

• by Shellface

  I also took a look at HAT-P-54's lightcurve today. Though at the outset I was looking for phase variations, the noise level of the data (213 ppm) is about an order of magnitude larger than the phase variations from all three effects combined, so that plan was a bust. Still, the K2 lightcurve is about 5 times more precise than the follow-up lightcurves in the discovery paper, so the transit observations are undoubtedly useful.

  But first, the lightcurve needs to be detrended. The HAT lightcurve shows a 15.6-day, ~1% variation that was interpreted as rotational modulation. The same variation is very clearly detected in the K2 lightcurve, and as they are only a factor of ~3 times smaller in amplitude to the transits they can easily be seen on the same scale:

  

  The above image shows the resulting model from my… simple detrending method (I call it "SEND MORE SINE WAVES"). The major period is found to be at P = 15.6 days, with the other periods being either the sensitivity ramp-up or harmonics (i.e P/2, P/3, P/4). Interestingly, the fourth harmonic is equal to the orbital period of the planet (which was noted in the discovery paper); I managed to get one model with a sinusoid at P/4, which had the maximum at the same time as the transit time, and thus suggests a spot was locked in phase with the planet's position above the star. Proper modelling of the lightcurve is required to understand this properly, but I don't recall ever seeing such a clear example of star-planet interactions in the out-of-transit part of a lightcurve.

  Anyway. The published planetary orbital period is almost an integer multiple of the K2 observing cadence (185.98:1), and thus the phased lightcurve shows "clumping" of datapoints around certain times. Nevertheless, the transit is quite clear and constrained:

  

  I took the de-trended lightcurve and the RVs + parameters from the discovery paper and plugged them in EXOFAST. The outputs are, on the whole, pretty much consistent with the discovery paper, and nothing particularly striking comes to eye. Take a look:

  
  

  Posted December 20, 2014 11:43 PM

• by JKD

  202070208 - potential transit at 1965.24 BKJD

  Posted December 21, 2014 8:55 AM

• by JKD

  202071448 - transit at 1947.23 BKJD

  Posted December 21, 2014 9:00 AM

• by JKD

  202071690 - transit at 1959.64d; transit duration ~1.7d

  Posted December 21, 2014 5:10 PM

• by Shellface

  Y'know, I was just looking through literature, and I happened upon this paper. I thought "hey, that lightcurve looks like that one I just spent a week analysing", and then I realised "wait, I never even considered if the companion could be a WD". So, uh, I may be a… little short-sighted. I'll try take a look at EPID 202072704's SED, but I have very little idea what I'm doing.

  @JKD Could you try organise these into single posts? It makes the thread look less all-over-the-place.

  1.) Possibly instrument noise (there are similar events at 1964.0, 1966.0 and a few other times)

  2.) Lightcurve looks fine, but the aperture doesn't appear to be centred on anything. The event is also fairly deep.

  3.) Already on pages 1 and 6. (did you not check?)

  Posted December 21, 2014 5:48 PM

• by Martti_Holst_Kristiansen

  @AjaMyAjax

  When I had a look at ID 202084843 it seemed to have three periodic signals. But as you and Troy mentions it does look like contamination.

  @Shellface - Great work!

  Posted December 22, 2014 10:27 AM

• by Shellface

  @Marti: thanks!

  After further consideration, I've decided that EPID 202072704's is more likely to be a M-dwarf than a white dwarf. The ingress and egress of the transit are fairly long (combined, about a third of the entire event) and the transit is significantly round-bottomed, whereas WD occultations have very short ingress/egress durations and almost flat transits. The secondary eclipse depth would translate to a companion radius of ~2 Rearth, which doesn't match well with the mass of ~0.09 Msol, and finally it would be difficult to explain how a WD could have an eccentric 3-day orbit post-mass transfer, while for a MS companion the eccentricity could simply be primordial.

  (Also, K2 could (potentially) detect a 2 Rearth planet around an A-dwarf! In the unphased photometry the event is invisible to the eye, but a periodogram could possibly detect it… I expect K2 will detect several transit events with depths of ~100 ppm with no prior knowledge.)

  I also realised that I forgot to look at EPID 202126888. A look at the 2MASS image reveals that the source is binary, with two components of similar brightness separated by about 1.4". The brighter component has slightly earlier colours (F5 vs G0), and given the small separation I suspect this is a physical binary.

  As for the lightcurve itself, the out-of-transit variations it holds look like rotational activity on a short timescale. Using that simple detrending method I showed previously determines that the dominant activity period is at about 1 day, which doesn't quite match half of the transit period. I suspect that both stars are contributing to the variability to the system, but which is which is not clear; perhaps follow-up photometry will be able to resolve that. Still, the doubled flux means that the actual transit is about twice as deep, so the transiting object is probably fairly large (~>1.5 Rjup). That doesn't exclude a planetary nature, but it makes it less likely. As the companion also does not fall into the "clump" HJ period distribution at 3-4 days (which makes it less likely to be a planet still), this one should probably be lower priority to follow-up.

  Posted December 22, 2014 8:52 PM

• by ajamyajax

  EPIC 202071289: looks stellar with a drop in flux of ~3.8%

  s1=1941.356 p1=3.0455 d1=0.1 (2.4 hours)

  

  K2 corrected light curve data credit: Vanderburg & Johnson (2014)

  Posted December 23, 2014 4:55 PM

• by ajamyajax

  EPIC 202088212: another low drop in flux candidate with a dim around 0.80%. Maybe a small offset in odd/even plot fit but not conclusive.

  s1=1939.303 p1=2.6203 d1=0.11 (2.64 hours)

  

  K2 corrected light curve data credit: Vanderburg & Johnson (2014)

  Posted December 23, 2014 4:57 PM

• by ajamyajax

  EPIC 202066192: appears to have TTV, dim around 0.82%; also an interesting O-C here that might show anti-correlation between two objects. But again, limited data and might not be statistically significant. However always worth posting something possibly interesting in my opinion.

  s1=1941.82 p1=3.2928 d1=0.075 (1.8 hours)

  ttv1 = [1941.82,1945.1165,1948.416,1951.705,1955.005,1958.274,1961.573,1964.874,1968.1627,1971.452]

  

  

  K2 corrected light curve data credit: Vanderburg & Johnson (2014)

  Posted December 23, 2014 5:00 PM

• by ajamyajax

  EPIC 202092782: only two sparse transits, but maybe a sign of a faint bgeb with possible differences in transit depth and duration here.

  s1=1946.485 p1=13.352 d1=0.11 (2.64 hours)

  

  K2 corrected light curve data credit: Vanderburg & Johnson (2014)

  Posted December 23, 2014 5:03 PM

• by ajamyajax

  EPIC 202087156: small dim with v-shaped curve and possible TTV with odd/even fit offset. And not sure what to make of O-C plot; tried several and this was the most interesting, but unsure if a real event or just a coincidence in the data.

  s1=1939.589 p1=0.9477 d1=0.125 (3.0 hours)

  ttv1 = [1939.589,1940.529,1941.4791,1942.4292,1943.379,1944.329,1945.279,1946.2195,1947.1693,1948.1093,1949.0593,1950.0094,1950.9592,1951.9092,1952.8593,1953.7995,1954.7495,1955.6995,1956.6492,1957.60,1958.55,1959.4892,1960.43,1961.39,1962.3295,1963.2694,1964.23,1965.17,1966.1195,1967.07,1968.0095,1968.97,1969.9094,1970.8494,1971.81]

  
  

  K2 corrected light curve data credit: Vanderburg & Johnson (2014)

  Posted December 23, 2014 5:05 PM

• by ajamyajax

  EPIC 202085597: appears stellar with maybe some odd/even offsets, and about 1.15% drop in flux. But the mixed plot seemed the most appropriate in this case. (Happy holidays to all.)

  s1=1940.019 p1=1.81416 d1=0.17 (4.08 hours)

  
  

  K2 corrected light curve data credit: Vanderburg & Johnson (2014)

  Posted December 23, 2014 5:10 PM

• by Shellface

  Oh, jimmy. That's a lot of lightcurves, aja!

  EPID 202071289: Despite the ridiculously large aperture, the 2MASS image suggests the central star is dominant. Source colours are ~G8, so transits are deep (>1.8 Rjup). V-shaped, narrow transits all point towards a moderately inclined binary, though a planet is admittedly not excludable. Not the best candidate.

  EPID 202088212: Single-source. Colours are ~G0, so the large 6-7d starspot modulation points to a young star. Transit depth implies companion radius ~1 Rjup, though the short bottom of the event means low-inclination. Decent candidate. I'll try to look at its out-of-transit lightcurve.

  EPID 202066192: Good aperture, single-source. Fairly faint, so colour errors mean spectral type can be mid A - early F. Companion radius is ~1.5 Rjup, but peculiarities like the irregular transit at 1958 days suggest some sort of issue in the system. Probably too faint and early to follow-up, but plausibly substellar.

  EPID 202092782: Single-source. Colours are mid-F. I suspect your issues with differing depths is an issue with zero-points, as the detrended lightcurve's transits (here) look equal. Depth of ~0.55% means companion radius of ~1 Rjup, but transits are short and V-shaped. Could definitely do with follow-up photometry before follow-up proper (Kepmag = 11.6 is favourable for that), but seems to be a plausible PC. Recon spectroscopy could exclude binary configurations.

  EPID 202087156: Single-source. However, the colours are conflictory (early-F, early G, mid-K), which points to a small-separation blend. The lightcurve shows clear quasi-periodic 4-day variations that match the profile of spots, but I notice that transits tend to occur around minima, which may be due to a more complex relationship between the two. On the face of it, not a good candidate, but some degree of follow-up is needed in order to actually understand what is going on here.

  EPID 202085597: The 2MASS image reveals that the source is binary, with a 2 magnitude fainter star lying 5" away that must be in-aperture. The source colours are blended, but they both seem to be late-type (K-M?). Though the transits seem fine, blending means I suspect this is a EB, in part due to the non-clump period. I think the odd-even diagram would be good to see, but this is not a very good candidate.

  Posted December 23, 2014 8:16 PM

• by ajamyajax in response to Shellface's comment.

  On a second look -- after a first glance I suppose, 202085597's odd/even plot does look a little eb-ish... Oh well, I will press on.

  Thanks for your efforts.

  

  Posted December 23, 2014 10:05 PM

• by Shellface

  Alright, I've done some quick work on EPID 202088212. Detrending this lightcurve is a good deal more difficult than it was with HAT-P-54 (though I could have told you that just from my experience with RVs; active G-dwarfs are a few times worse than active K-dwarfs), and indeed, I failed to detrend it completely due to, er, technical limitations . Still, the data is detrended to a useable degree.

  I plugged in my lightcurve and a few rough input parameters into EXOFAST, which found a meaningful solution to the data. Given that the transit is grazing there arebound to be issues with the solution, but it seems plausible. Observe:

  

  The modelled star is probably slightly too evolved, and most of the transit parameters will have rather healthy errors, but everything here seems around what I expected. It's interesting to note that all this can be derived from the lightcurve and the colours of the source, no further observations required. Sure seems cost-effective, huh?

  Anyway. The phased lightcurve shows visible evidence that my detrending was unsatisfactory, as it shows aperiodic rises and falls across its face that match those in the unphased lightcurve. However, this variation lies close to the noise floor of the data, so it doesn't affect things too badly. Around phase 0.5, there is no particularly compelling evidence for an eclipse:

  

  I crudely estimate an upper limit of 40 ppm on the eclipse depth of the companion. The entire phase curve shows little variation, so for the ellipsoidal effect - likely the most dominant of the three out-of-transit effects - I estimate an upper limit of 50 ppm.

  Recalling the equations I used on page 10, The resulting upper limit on the albedo of the companion is ~0.1, and the upper limit for its mass is ~17 Mjup. Thus, the companion seems to be a typical dark Hot Jupiter.

  So, yeah! That's the first time I've gotten out-of-transit analysis to get a planet-seeming result. I guess this should be a higher-priority PC? Honestly, not sure how K2 follow-up works, maybe I'm late to the party. At least this shows that this kind of analysis can provide a meaningful result!

  Also, it just clicked in my head that the "Correction" column in the datafile might be the detrended flux used on the respective page. If it is, then I'll be kicking myself for a while, but it's quite late here so I won't try to improve on my result today.

  Posted December 24, 2014 1:08 AM

• by ajamyajax in response to Shellface's comment.

  SF, nice work yet again. FWIW here is a KOI list of confirmed HJ's that might be similar:

  kepid,koi,period,epoch,duration,disposition,earth radii,stellar radii,depth,teq

  10666592,K00002.01,2.204735365,121.3585723,3.88216,Kepler-2 b,16.39,1.991,6690.6,2025

  6922244,K00010.01,3.522498573,121.1194294,3.19061,Kepler-8 b,14.83,1.451,9379.3,1521

  8191672,K00018.01,3.548465405,122.9014699,4.57705,Kepler-5 b,15.28,1.746,7451.9,1640

  11804465,K00020.01,4.43796303,171.0091193,4.70104,Kepler-12 b,18.22,1.415,16721.1,1338

  6046540,K00200.01,7.340714746,134.3457121,2.9936,Kepler-74 b,14.41,1.498,8679.5,1155

  10619192,K00203.01,1.485710952,132.7935604,2.2873,Kepler-17 b,14.8,1.018,21801.9,1561

  8219268,K02133.01,6.24668005,136.38661,11.176,Kepler-91 b,15.39,6.528,411,1917

  10552611,K00338.02,3.10763873,132.62892,2.274,Kepler-141 b,16.16,18.939,77.4,3961

  5780885,K00097.01,4.885488953,134.2768383,5.1313,Kepler-7 b,17.29,1.962,7569.3,1499

  Posted December 24, 2014 1:54 PM

• by ajamyajax in response to ajamyajax's comment.

  Edit: I posted only maybe inflated hot Jupiters above with radii > 14. (Sorry 'bout that.)

  Here is the scan with earth radii > 11 but < 20, and both lists limit the period < 10.

  11446443,K00001.01,2.470613385,122.7633008,1.74259,Kepler-1 b,12.85,0.95,14186.4,1344

  10666592,K00002.01,2.204735365,121.3585723,3.88216,Kepler-2 b,16.39,1.991,6690.6,2025

  6922244,K00010.01,3.522498573,121.1194294,3.19061,Kepler-8 b,14.83,1.451,9379.3,1521

  5358624,K00830.01,3.525632561,170.0479922,2.614,Kepler-428 b,11.87,0.788,24046.3,955

  757450,K00889.01,8.88492268,169.991758,2.07864,Kepler-75 b,11.02,0.843,17670.4,770

  9818381,K00135.01,3.024092548,132.4169214,2.73608,Kepler-43 b,12.1,1.345,8004.8,1475

  8191672,K00018.01,3.548465405,122.9014699,4.57705,Kepler-5 b,15.28,1.746,7451.9,1640

  10874614,K00017.01,3.234699312,121.4865705,3.60111,Kepler-6 b,13.41,1.291,10814.1,1355

  9631995,K00022.01,7.891448474,177.2500095,4.30403,Kepler-422 b,12.24,1.193,10612.6,1000

  9651668,K00183.01,2.684328485,133.3548211,2.68062,Kepler-423 b,12.43,0.908,18715.3,1291

  11502867,K00195.01,3.217518593,133.6320261,2.12039,Kepler-426 b,11.68,0.903,15070.3,1200

  11804465,K00020.01,4.43796303,171.0091193,4.70104,Kepler-12 b,18.22,1.415,16721.1,1338

  6046540,K00200.01,7.340714746,134.3457121,2.9936,Kepler-74 b,14.41,1.498,8679.5,1155

  7877496,K00202.01,1.720861324,133.0209957,2.03459,Kepler-412 b,12.53,1.124,10541.3,1681

  10619192,K00203.01,1.485710952,132.7935604,2.2873,Kepler-17 b,14.8,1.018,21801.9,1561

  9595827,K00217.01,3.905081985,133.4149506,2.85516,Kepler-71 b,13.14,0.887,22670.3,1046

  9305831,K00204.01,3.246732651,133.379039,3.0509,Kepler-44 b,12.71,1.457,7414.1,1460

  8219268,K02133.01,6.24668005,136.38661,11.176,Kepler-91 b,15.39,6.528,411,1917

  5794240,K00254.01,2.45524062,170.8217486,1.74417,Kepler-45 b,11.03,0.552,40521.5,730

  10552611,K00338.02,3.10763873,132.62892,2.274,Kepler-141 b,16.16,18.939,77.4,3961

  10418224,K00428.01,6.873165232,172.518919,6.8593,Kepler-40 b,13.8,2.179,3955.5,1482

  5780885,K00097.01,4.885488953,134.2768383,5.1313,Kepler-7 b,17.29,1.962,7569.3,1499

  10264660,K00098.01,6.790121599,138.088257,6.1391,Kepler-14 b,12.21,2.075,2252.3,1445

  4570949,K01658.01,1.544928883,133.5488107,1.42784,Kepler-76 b,13.67,1.444,5915,2013

  Posted December 24, 2014 5:42 PM

• by ajamyajax in response to ajamyajax's comment.

  Ot: robert gagliano,

  I might have figured out why PH2 was dropping that large list you posted before. It doesn't like "greater than" or "less than" symbols -- thinks they are hypertext.

  I worked around that in my post above using the html equivalent: type "ampersand gt;" for "greater than" and "ampersand lt;" for "less than."

  Just trying it again to see if it works: > < > < And case doesn't matter. Hope this helps.

  Update: and "ampersand ge;" is for "greater than or equal to" etc. [≥ ≤]

  Posted December 24, 2014 5:50 PM

• by Dolorous_Edd

  About the LC troyw posted on page 2 of this thread

  Taken apart from part of the superstamp, 200000811 has a possible planet with a period of 7.556 days.

  I have tried to normalize and manually detrend the LC and here the result

  Download detrended LC

  Another variant with shoulders (before and after transit) preserved

  

  The varying depth of the transits is the result of my poor detrending skills, I believe, tried to remove shoulders from transits

  Here phased plot from the original LC ( left , right is individual transit)

  
  

  And here is SkyView

  DSS 2 Red 1' x 1' and Link to SDSS

  

  Would be cool if these transits are real, because this target appears to be not claimed by any GO?

  Posted December 28, 2014 5:16 PM

• by JKD in response to Dolorous Edd's comment.

  perfect analysis,
  congratulations, a great find

  Posted December 28, 2014 11:10 PM

• by troyw in response to Dolorous Edd's comment.

  Would be cool if these transits are real, because this target appears
  to be not claimed by any GO?

  That's the best part about this particular campaign. Although most of the superstamp is taken up by overcrowded sources within the M35 star cluster, this part of the stamp is on the edge of the superstamp. I've checked up to 200000835, so there are still plenty of non-GO places to look. Future campaigns may have less opportunities, but also keep in mind that not all GO teams are looking specifically for planets.

  Posted December 28, 2014 11:58 PM

• by Shellface in response to Dolorous Edd's comment.

  perfect analysis, congratulations, a great find

  Let's not count eggs before they're hatched…

  Though I'm missing the Kepler magnitude, the source's J-H and H-K are most consistent with a late-F spectral type. Using a set of loose priors, EXOFAST agrees, making the star out to be a ~F8IV star. The companion radius becomes ~1.2 Rjup, with the transits being properly star-crossing (b = 0.7).

  Thus, the transits themselves seem fine, and are well modelled. However, I cannot explain those ramps on either side of the transit. As physical explanations are sub-par, I must suspect that they are an observational issue - either instrumental, or some amount of system blending.

  As the star's magnitudes in the 2MASS bands (infra-red) are fairly bright, and the star is slightly earlier-type than solar, then it must be similarly bright in the visible (around magnitude 11). Its brightness naturally makes further observation easier, which would be justified as this is a decent-looking candidate, failing those odd ramps. Perhaps they will be explained in time.

  Edd, nice job working with the raw data. It probably wouldn't be too consequential that the star isn't targeted under any specific programs, but that does mean it's less-known than the others in this thread - for better or for worse.

  Posted December 29, 2014 12:16 AM

• by troyw

  I don't think a well extracted lightcurve would have those shoulders on the sides of the transits. In fact, if you used my original curve, those shoulders are an effect of using a simple "boxcar" detrending method. If I had excluded the transits from the detrending function, the shoulders would not have appeared. My calculation for combining the flux from the various pixels is also likely off, so the relative flux that comes from those numbers is likely off too. (Meaning, I think this is a smaller candidate than my calculated flux might suggest).

  Posted December 29, 2014 1:19 PM

• by Shellface in response to troyw's comment.

  It took a couple of tries, but I think I understand. Would it be possible to address the issue in a simple manner?

  In the meantime, that probably settles the lightcurve issue, so I'm gonna say that this is a good candidate, moreso if the transit depth is actually smaller. Since this may or may not be on the radar of the K2 team (is there going to be a K2 candidate list release like there was for Kepler?), it would be worthwhile to take note of it here.

  Posted December 30, 2014 6:25 PM

• by Dolorous_Edd in response to Shellface's comment.

  It probably wouldn't be too consequential that the star isn't targeted under any specific programs, but that does mean it's less-known than the others in this thread - for better or for worse.

  The whole M35 thing ( and our target as well since it located in M35 superstamp) goes under GO0034

  K2 and M35: Opening the Window on Precision Light Curves of Low Mass Main Sequence Stars of
  Known Age and Metallicity

  http://keplerscience.arc.nasa.gov/K2/docs/Campaigns/C0/GO0034_Stauffer.pdf

  Edit 01/12/2015 (12.01.2015)

  /Also have to mention GO0102

  http://keplerscience.arc.nasa.gov/K2/docs/Campaigns/C0/GO0102_Sandquist.pdf
  and this white paper

  http://keplerscience.arc.nasa.gov/K2/docs/WhitePapers/Guzik_KeplerOpenClusterAgeSequence.pdf

  End of Edit

  However judging from GO name and proposal it seems they are mainly interested in stellar variability

  BTW searched for additional surveys in this area , found only SuperCOSMOS POSS 2 Red 1' x 1'

  Green circles are positions of photometric objects from SDSS

  

  Also this part of sky was observed by Spitzer at 54195.112 MJD dunno how useful it is

  IRAC 8.0um - IRAC 4.5um

  Also was observed by Canada France Hawaii Telescope

  

  EDIT 01.12.2015 (12.01.2015 )

  SDSS color-color charts

  

  

  END OF EDIT

  Posted December 30, 2014 6:47 PM

• by Shellface in response to Shellface's comment.

  So, I did a quick-and-dirty analysis of EPID 202126884's out-of-transit lightcurve. Learning from the previous case of EPID 202072704, it's quite obvious from the ~1000 ppm phase variations here are due to a stellar companion. I won't detail the processes here because nothing I did is new, so have some bullet points:

  • The companion eccentricity is about 0.4, and as can be seen from the quasi-symmetrical phase variations, ω ≈ 180°

  • If eclipses are present - which they should be, given the system architecture - they are not particularly apparent. I suspect the signal is drowned out by the out-of-transit variations, which have about the same level of variation in the eclipse time as the eclipse itself.

  • Due to the companion eccentricity, beaming has a fairly easily detectable effect on the lightcurve. This gives an additional mass ratio measurement. It is about an order of magnitude smaller than the ellipsoidal effect.

  The resulting companion mass ratio is ~0.08. It is difficult to give a value to M because the primary's log g is not well determined (EXOFAST cannot be used easily here because of the large eccentricity). Going with a typical mass for a G0IV star of M ≈ 1.2 Msol, m ≈ 0.10 Msol. Thus, this seems to be another unusually small companion to a normal star, which masquerades as a planet due to its position on the mass - radius diagram. False positive.

  Posted December 31, 2014 10:36 PM

• by Dolorous_Edd

  Nevermind , I had to redone this thing because the spacecraft achived more or less stable pointing at 1936BKJD

  About 200000811 .. again

  I was able to set up PyKE up and runing and did following horrible things

  0)Deleted all rows with TIME less than 1936 BKJD and = NULL

  1. I run keptrim script from PyKE package on the original superstamp with following parameters

  column = 51 ; row = 36 ; imsize = 12

  Download new TPF (12Mb)

  Well .. in theory it should contain only star with potential PC

  

  2. run keptrim with following parameters

  column = 51 ; row = 36; imsize = 5

  Then run keppixseries script from package

  plottype full; filter; function boxcar; cutoff 1.0

  The result can be downloaded here(1 Mb)

  3 files in archive: 1) keppix5.png 2) m35keppix.fits 3) m35trimmed5.fits

  Edit 20:25

  Allllright .. pixel values are consistent with the original, but coordinates are off

  strange why does it happen?

  Edit 2

  Anyway here is extracted fluxes from new TPF
  With few caveats

  1. start from 1934 brjd since everything else is useless
  2. removed NULL rows

  Download(~3.7Mb)

  Maybe create larger TPF say 17x17 or 20x20? or this one is fine?

  EDIT 01/13/15 (13.01.2015)

  Another variant of Keppixseries

  Central pixel C = 49 R = 33 imsize = 7

  

  View full image

  download archive with fits, etc ( ~1Mb )

  END OF EDIT

  Posted January 2, 2015 10:47 PM

• by andrew418

  Hi everyone,

  I extracted the light curve for the superstamp candidate in 200000811 using my pipeline, and uploaded it here: https://www.cfa.harvard.edu/~avanderb/ep200000811.csv

  Best,
  Andrew

  Posted January 3, 2015 8:08 AM

• by zoo3hans

  It looks quite convincing. Period about 7.56 days. Maybe there is another much smaller body visible at about BKJD 1949.5 (with a longer period).

  

  Posted January 3, 2015 8:51 AM

• by Dolorous_Edd

  Period about 7.56 days.

  Yep, pretty much

  

  

  Posted January 3, 2015 9:11 AM

• by troyw

  Thanks Andrew!

  Posted January 3, 2015 2:52 PM

• by Shellface in response to andrew418's comment.

  Thanks for that, Andrew!

  After correcting the lightcurve for the sensitivity ramp-up (which is the reason Edd's phase curve looks a bit wonky), I get a lightcurve with some good-looking transits. The event at ~1949.5 days is rather long (a day) and too irregular to be a transit, so I doubt it's real.

  Inputting the lightcurve and some sensible priors into EXOFAST results in a sensible fit:

  

  

  Note that:

  • Because of its long(ish) period, the stellar parameters and, hence, the absolute planetary parameters, are rather sensitive to the priors. The stellar parameters with exception to perhaps Teff will have to be adjusted, so any formal parameters for the system will be substantially different in some regards.

  • The transit depth EXOFAST finds seems to be physically wrong for some reason (from the lightcurve, the actual depth is ~0.007). The radius ratio must therefore be higher (~0.084).

  Though a/R is too large for out-of-transit variations to be detectable, there is no clear eclipse signal, which excludes some false positive scenarios. Once again, this is a good candidate.

  Posted January 3, 2015 5:00 PM

• by Dolorous_Edd

  EPIC 202088212 was in detail discussed by ajamyajax & Shellface on page 12 of this thread

  My info is useless now, but good for an exercise ( well .. for me)

  EPIC 202088212 goes under GO0111_LC

  Sanchis Ojeda DETECTION OF EARTH-SIZE PLANETS USING K2

  Here is my take on detrending

  

  Download detrended LC

  

  Skyview DSS 2 Red 1'x1'

  Also this area is imaged by POSS I & POSS II surveys

  

  Here is Keppixseries for two 6x6 pixel squares centered on pixel with coord Row = 593 Column = 272 and R = 597 C = 274

  I guess if there was a BGEB like really obvious one we would have seen it now

  

  View full image

  Second square R = 597 C = 274

  

  View full image

  Download archive with trimmed pixel squares, keppixseries fits, pictures ~4Mb

  Mask of pixels covered

  

  Pixel mask looks extended perhaps need to repositon and do another square

  Edit

  Maybe slightly better version of dtr LC with reduced noise level

  

  Download

  Posted January 8, 2015 3:48 PM

• by Shellface in response to Dolorous Edd's comment.

  Looks good! Our lightcurves seem pretty much the same (though maybe yours can constrain eclipses a bit better).

  Posted January 8, 2015 4:04 PM

• by Artman40

  From Exoplanet Archive I got an e-mail:

  "We are currently working with the Kepler project to finalize
  the plans for K2 confirmed planet names. Once that is done,
  HIP 116454 b will be assigned a K2 name. There will be
  a listing of K2 planets and if there are enough of them,
  a K2 flag in the confirmed planets table."

  Posted January 8, 2015 10:04 PM

• by Dolorous_Edd

  How about EPIC 202093968?

  According to SIMBAD it is CCDM J06246+2108AB -- Double or multiple star

  EPIC 202093968 goes under GO0111

  Sanchis Ojeda DETECTION OF EARTH-SIZE PLANETS USING K2

  I have to say that it is rather strange choice to look for earth size planets

  http://talk.planethunters.org/#/subjects/APH0000bcr?quarter=0-1

  EB, Blend?

  Multiple stars in apperture, odd phased plot ... blend?

  https://www.cfa.harvard.edu/~avanderb/k2c0/ep202093968.html

  Detrended LC

  Download

  Phased plot looks odd ( or doubling the period will yeld more consistent plot?? )

  • plus flux can be diluted hence the transits can be deeper in reality

  

  Posted January 10, 2015 10:24 AM

• by ajamyajax in response to Dolorous Edd's comment.

  EPIC 202093968: another low drop in flux candidate that is also (maybe) a little more interesting, because I got a possible secondary signal in both my detrended data and Dolorous Edd's detrended data. It could be a glitch/still working on the detection process which requires extra care when detrending, but here are the charts without bias for you to decide.

  s1=1941.55 p1=2.4697 d1=0.12 (2.88 hours)

  

  
  

  

  Posted January 10, 2015 2:28 PM

• by Shellface

  Looking at the WDS entry, the source is a close visual binary (~2" at the current epoch), though the components don't seem to be physically related. Since the secondary is only 1.2 magnitudes brighter than the primary, there must be a substantial amount of flux blending in the lightcurve.

  The out-of-transit variations visibly vary at half the transit period, which is consistent with ellipsoidal variations. Their large amplitude implies a massive companion, perhaps a low-mass star.

  Since there are at least two bright stars in the Kepler aperture, it is possible that both can host transit signals. With that in mind, what else do you see, aja?

  Posted January 10, 2015 5:30 PM

• by ajamyajax in response to Shellface's comment.

  Well I inspected my detrended data closely this time for possible p=13.28-13.33 glitch intervals, and starting around 1941.15 BJD there is a possible "three-peat." So my guess is my L-S-P picked up that period. Perhaps that is what the other team's software did also before their DETECTION OF EARTH-SIZE PLANETS USING K2 proposal?? And sorry about the possible false positive here, but those things happen.

  Posted January 10, 2015 7:39 PM

• by Shellface

  Well, I imagine it's been some time since anyone's touched the C0 data. However, in the interest of completeness, I'm going to go over what I did not previously analyse.

  I will also note that I did not previously realise that reddening was so severe for this field. This means that previous colour-based values for stellar temperature will be too low by perhaps a few hundred kelvin, which will have some influence on the derived parameters. Reddening will be similarly severe for the C2 data (moreso towards the star-forming regions, I imagine) as it lies just as close to the galactic plane as the C0 field, which will be important to keep in mind since it will be available for analysis soon.

  EPID 202083828: Kepmag = 14.9, reddening-uncorrected colour spectral type ~K5

  To the eye this is a good candidate, with shallow, flat-bottomed eclipses. I detrended the lightcurve as normal, then fed the resulting data into EXOFAST. With the expectation of strong reddening for this faint (and thus probably distant) star, the prior temperature was put roughly where I expected it to be, with loose bounds (5300 ± 500 K), and the other priors were based on sensibility. The resulting model was as follows:

  

  This is indicative of a companion with approximately the same radius as Neptune, transiting a mid-G dwarf. Planet Candidate. The low metallicity is probably not statistically significant from the transit model alone, but it would not be entirely insensible.

  With Kepmag = 14.9, this star is too faint to extensively follow-up, and so this will probably have to be one for statistical validation over confirmation. Regardless of the star's faintness, this is one of the shallowest transits and smallest candidates from the C0 field.

  Posted March 20, 2015 1:11 AM

• by ajamyajax in response to Shellface's comment.

  Nice work SF, as usual. I think I've got another small system that Planet Hunters noticed here recently (C1 data), but blended transits are a real challenge in K2 data... More on that one later.

  Posted March 20, 2015 5:15 PM

• by Shellface

  @aja: Thanks again. I imagine you're referring to EPID 201202065? I'll try to do what I can there, but that is undoubtedly scraping the noise floor for such an enormously faint star.

  EPID 202137637: This target was discussed a little on page 5. Again, the 2MASS point source catalogue indicates there are at least 3 similarly bright sources in the main aperture. This is obviously rather problematic. I list the colour spectral types, with no correction for reddening, below:

  centre: M3 (or possibly ~K5, though it's less likely)

  bottom-left: ~F7

  bottom-right: ~G1

  If we say the stars are reddened by ~9 spectral types like EPID 202083828 (I know "amount of spectral types of reddening" doesn't make much sense, but it's an approximation), then the stars have spectral types of approximately K4 (G6), A8, and F2.

  Andrew indicated that the central (late-type) star is the transit host. Using the MAST interface, I observe that the transit depth decreases from 0.041 from the smallest circular aperture to 0.016 for the largest, which agrees with that statement and shows the degree of blending that occurs here.

  Something I have learned to pick up on is that the transit length shown by aja's diagram on page 5 (about 6 hours, if we make a loose correction to the 30-min integration times) is very long for an orbital period of 6.62 days. Indeed, I estimate a/R to be ~8.8 (as compared to an expected value of ~20-25 for a K4 dwarf, and ~10-15 for a G6 dwarf), which implies the density of the star being transited to 0.29 g/cm^3, which gives a surface gravity of log ~3.75 cgs (compared to ~4.55 for a K4 dwarf, and ~4.40 for a G6 dwarf). This indicates the star being transited is a subgiant. If the ~K4 (~G6) star is that subgiant, then the companion radius is perhaps 3.4 (3.2) Rjup, which would indicate that this is a star.

  As a sanity check, I see that ellipsoidal variations with amplitude ~10% of the transit depth (~0.004) are visible to the eye for the smallest apertures, which strongly indicates the companion is of stellar mass. Thus, I will mark this as a FALSE POSITIVE, be it a convincing one.

  Eclipses are also tenuously identifiable in the secondary minima of the ellipsoidal variations. With a depth ratio of ~13.5, the temperature ratio is ~1.92, so for a K4 (G6) primary the secondary spectral type is ~M8 (~M5). Neither of these are particularly consistent with the ~3 Rjup radii, but that could probably be resolved by altering the parameters of the primary slightly. Ultimately, they are consistent with a stellar companion, which is the most important thing that can be derived from this.

  Posted March 23, 2015 10:14 PM

• by ajamyajax in response to Shellface's comment.

  Re: I imagine you're referring to EPID 201202065? I'll try to do what I can there, but that is undoubtedly scraping the noise floor for such an enormously faint star.

  Yes, the C1 target I mentioned earlier was 201202065. And unless you consider it too faint for much optimism, I would appreciate your experienced stellar insights (see I tried not to infer a professional or highly trained background this time anyway 😃. I do realize the blended transits I suggested for that one are speculative for all. But thanks for considering it.

  Posted March 24, 2015 12:34 AM

• by Shellface

  Getting some of the worse targets out of the way first…

  EPID 202137209: I agree with's troy's observation of eclipses on page 1. The reddened source spectral type is M7 ± 2, and I estimate the de-reddened spectral type to be in the range G5 - K5. The transit length is consistent with a dwarf host, so the deep (0.03) transits and eclipses (~0.005) are indicative of a stellar companion. This is definitely a false positive.

  EPID 202066212: The source aperture contains two similarly bright stars, separated by about 9" (~3 pixels). The positioning of the centre of the aperture makes it difficult to separate the two, so the lightcurve is contaminated regardless of aperture. It is thus not possible to perform a realistic analysis of the data. The transits are shallow (0.002), and thus even for large amounts of blending the transits can be of planetary depth. The source is fairly faint (Kepmag = 14.5), but resolved photometry could be valuable. The fainter star has a reddened spectral type of ~G5, while the brighter's spectral type is difficult to place, but it is probably somewhat earlier than the other star. Tentative planet candidate.

  EPID 202085597: This source also contains two stars, but this time they have significantly different brightnesses (ΔJ = 2.27, etc.). The transits disappear for the smallest apertures, so they are probably associated with the fainter star, in which case they are must be far deeper. False positive.

  EPID 202126847: The source aperture again contains two stars, but the transits appear to be on the brighter star. The colours of the two stars are equal to the errors, and I estimate they are both late-A - to - early-F. The transit depth (0.017) is thus too deep to be planetary. The V-shaped transits are indicative of strong grazing, which means the actual companion radius is even larger. False positive.

  Posted April 1, 2015 10:00 PM

• by ajamyajax in response to Shellface's comment.

  202066212: and I know search isn't easy here, but a secondary and a possible eb was mentioned for this LC before by others. An odd/even chart suggests that is more likely than not, in my opinion also.

  

  Posted April 3, 2015 2:00 PM

• by Shellface in response to ajamyajax's comment.

  Thanks, aja. I couldn't clearly agree with the idea that EPID 202066212 had varying transit depths when I wrote previously due to the shallow transits, but your diagram is quite convincing. It seems reasonable to label it is as a false positive.

  EPID 202093020: This star experiences transits every ~4.14 days. The transits appear to be rather short for the orbital period and fairly V-shaped, indicative of a high impact parameter.

  The lightcurve also shows rotational variability with a major period of ~4.18 days, which is almost the same as the transit period. This can be construed as tidal locking by the companion (indicating it is massive), or that the star is young.

  I detrended the lightcurve as before. This particular case required even more sinusoids than normal, presumably due to the short rotational period (and thus fast evolution of spots). I found the reddened spectral type of the star to be ~K2, and thus estimated the physical spectral as early-G. I plugged the data into EXOFAST with no priors that strongly influence the derivation of the impact parameter, and received this model:

  

  This model has an impact parameter of 1, which requires exactly(ish) half of the transiting body to cross the star, and hence makes the companion radius 2 Rjup with 1% transits. Such a large transiting companion would likely not be a planet.

  On the other hand, attempting a model with a prior on the radius ratio and the stellar surface gravity results in the following mode:

  

  This model has essentially the same goodness-of-fit as the previous model and approximately the same lightcurve shape, but has companion parameters far more consistent with a planet. As this is largely dependent on the derived impact parameter (0.85), it is fairly evident that the transits cannot be used to clearly distinguish whther the companion is planetary or not, because Kepler's 30 minute LC integration times significantly blurs the shape of these short transits.

  The out-of-transit lightcurve is fairly noisy, and hence it probably cannot be used to detect any eclipses should they be present. Hence, the Kepler lightcurve cannot determine whether this star's companion is planetary or not.

  I suppose that a resolved, ground-based lightcurve would have significant capability to properly determine the impact parameter of the companion, and identify any blending that may be present. Radial velocities would also be strongly sensitive to the companion mass if it is particularly massive, though false positive scenarios should obviously be excluded first. Planet candidate.

  Posted April 7, 2015 3:13 PM

• by Dolorous_Edd in response to Shellface's comment.

  UKIRT image for EPIC 202093020

  1'x1'

  

  Also

  https://www.cfa.harvard.edu/~avanderb/k2c0/ep202093020.html

  Posted April 8, 2015 7:51 AM

• by ajamyajax

  202087156: revisiting this candidate with a bit more to work with, I think there is a decent chance of a hot gas giant in a high-impact orbit here. An F class star ~1.35x R_sol seems to work fairly well (12.30 KepMag), as does this transit duration. And the TTV I believe is there just seems unusual for a stellar companion with this short a period. So there could be another PC nearby as well.

  Also seems to me there should be some effect on the primary flux if this transit is caused by a stellar companion... And there are stars nearby, but can't see how any of these could transit at this short a period OR contribute much as a blended BGEB. Just my two cents, as always.

  s1=1939.589 p1=0.94764 d1=0.097 (2.328 hours)

  ttv1 = [1939.589,1940.529,1941.4791,1942.4292,1943.379,1944.329,1945.279,1946.2195,1947.1693,1948.1093,1949.0593,1950.0094,1950.9592,1951.9092,1952.8593,1953.7995,1954.7495,1955.6995,1956.6492,1957.60,1958.55,1959.4892,1960.43,1961.39,1962.3295,1963.2694,1964.23,1965.17,1966.1195,1967.07,1968.0095,1968.97,1969.9094,1970.8494,1971.81]

  EPIC, 2MASS, J mag, H mag, K mag, J - H, H - K, (J-H spectral type, stellar mass est) (H-K spectral type, stellar mass est)

  202087156 , 2MASS J06240706+1446172 , 10.986 , 10.826 , 10.714 , 0.16 , 0.112 , ('F4V', 1.37) , ('K3V', 0.81)

  au min-max 0.02 0.02
  
  stellar diameter in solar units min-max 1.33 1.43
  
  stellar mass in solar units min-max 1.175 1.205
  
  period in days min-max 0.941 0.953
  
  duration in hours min-max 2.251 2.4
  

  F class stars: 1.04–1.4x M_sol, 1.15–1.4x R_sol
  
  https://en.wikipedia.org/wiki/Stellar_classification
  

  (from NEA) 2MASS Objects within search area:
  
  2MASS Designation RA [decimal degrees] Dec [decimal degrees] Distance [arc sec] J [mag] V or R [mag] Photometric flags
  
  06240706+1446172 96.029454 14.771459 0.02 10.986 11.60 AAA
  
  06240804+1446220 96.033508 14.772791 14.92 16.367 18.70 BCU
  
  06240770+1445564 96.032091 14.765675 22.76 14.827 15.90 AAA
  
  06240892+1446021 96.037201 14.767257 30.94 14.897 15.90 AAU
  
  06240658+1446490 96.027451 14.780278 32.50 16.420 null BCU
  
  06240441+1446263 96.018386 14.773988 39.57 15.152 16.90 AAA
  

  
  
  
  
  

  RA/Dec:
  
  06 24 07.068, +14 46 17.26
  
  96.0294500, 14.7714600
  

  Posted August 27, 2015 8:22 PM

• by ajamyajax

  Re 202126884 last discussed by SF as a false positive. More evidence of that is the possibility of a giant or subgiant here of ~2.32 R_sol based on the long relative duration for this period. That would make any potential PC transit radius ~21.x Re.. Also the transit events (shown in cyan below) are well-aligned with the stellar flux cycle (highlighted in broader magenta and orange bands of the same period) which SF also discussed I believe, and suggests a binary transit.

  s1=1940.948 p1=5.3205 d1=0.3 (7.2 hours)

  EPIC, 2MASS, J mag, H mag, K mag, J - H, H - K, (J-H spectral type, stellar mass est) (H-K spectral type, stellar mass est)

  202126884 , 2MASS J06264300+2512178 , 11.225 , 10.958 , 10.884 , 0.267 , 0.074 , ('G0V', 1.09) , ('G2V', 1.0)

  Semi-Major Axis a (A.U.) = 0.061
  
  Stellar diameter ratio = 2.32
  
  Stellar mass ratio = 1.07
  
  Period ~= 5.32 days
  
  Duration ~= 7.2 hours
  

  From NEA, K2 Targets within search area:
  
  EPIC Number RA [decimal degrees] Dec [decimal degrees] Distance [arc sec] Kepler-band [mag] Campaign Number
  
  202126884 96.6792 25.2050 0.16 12.300 0
  

  (no K2 radius or mass on NEA yet)
  
  epic_number,k2_teff,k2_rad,k2_mass,k2_kmag
  
  202126884,,,,10.884
  

  Listed as TYC 1883-122-1 -- Star on Simbad, Proper motions mas/yr : 4.9 0.8

  
  

  Posted March 1, 2016 1:40 AM