Planet Hunters Talk

K2 asteroid candidates

  • ajamyajax by ajamyajax

    Well, looks like a paper on K2 field asteroids now... This reminds me of Troy's animated images on YouTube which were really cool. Too bad the pros don't publish those yet. 😃 But fwiw I noticed this paper's examples chart a little differently than mine, so maybe they used their own K2 corrective software instead of Vanderburg & Johnson's(?)

    In any case, I did a quick scan of the K2 data for more asteroid candidates and came up with a few. And the lists below are just from a narrow scan, there are certainly more.

    "Main-Belt Asteroids in the K2 Engineering Field of View"

    http://arxiv.org/abs/1501.05967

    Paper examples: EPIC 60017873, 60018798, 60017987

    60017873

    60018798

    60017987

    Possible K2-E2 asteroids (or glitches?)

    60018882

    60018909

    60018995

    60019013

    60019552

    60019791

    60020174

    60021757

    60021855

    60023901

    60044078

    ...

    Possible K2-C0 asteroids and flares (left in just for comparison)

    202061316

    202061321

    202065024

    202067951 (flares)

    202068077 (flares)

    202068113

    202068509

    202093664

    202135853

    202137300

    ...

    Edit: see Troy's animations here:

    https://www.youtube.com/watch?v=6sqOyCuu0wA

    Posted

  • Artman40 by Artman40

    How well can Kepler spacecraft used to characterize transiting asteroids?

    Posted

  • Shellface by Shellface in response to artman40's comment.

    Photometry can determine the rotational period of the asteroid, as is demonstrated in the paper. Gravitational lensing, which would give the mass of the asteroid, is probably difficult to extract for the mechanical setups one would expect due to the low masses of most asteroids and such, though it could perhaps be worth considering in particularly favourable situations.

    I recall that a Trans-Neptunian Object was accepted for study in Campaign 1. Kepler's ability to detect rotation is presumably similiar between the two types of objects, but asteroids have far higher velocities across the celestial sphere, hence star crossings are much more frequent.

    Posted

  • troyw by troyw in response to ajamyajax's comment.

    The asteroids were the first thing I noticed in the ET data. C1 has one nice one that I was trying to figure out the path of the other day to see how many target masks could pick it up across the 80 day time frame. I'll post results for that at some point (been very busy at work lately). A nice slow bright one too....

    Cool to see that a team has put together a paper for this.

    Posted

  • ajamyajax by ajamyajax in response to troyw's comment.

    Looking forward to that. And if it's slow and bright, maybe some periodic rotation is visible(?)

    Posted

  • troyw by troyw

    enter image description here

    201555556 is where I first spotted this one. It enters the mask @ BJD 1999.90 and goes until 2000.39. The lightcurve for the star target spikes as the asteroid crosses the path of the star.

    Posted

  • ajamyajax by ajamyajax in response to troyw's comment.

    Troy, interesting stuff for sure. I viewed each frame with an asteroid image in it on my PC (frames 109-134). And to my non-expert eye -- it looks like it is rotating, but I couldn't see a pattern. If all right with you, I could post the sequence here tomorrow for others to examine as well, just to save you the time. Maybe somebody else can spot a rotational pattern.

    Posted

  • troyw by troyw

    Absolutely. I thought I saw rotation characteristics from some of the short cadence data in the ET phase... I'll have to check and see if that particular one is in the paper and see if I can extract the light curve again. Only 26 frames for this one though from long cadence, There is one that might be worth tracking in C0 that crosses the entire M35 field that starts in 200000954 all the way to 200000834(ish) that might yield a good number of data points, and it looks like avoided the entire stamp in that paper,,

    So little time though, especially trying to get a handle on the correction algorithms for AKO-TPF. However, that might be your best bet for looking at the "possibles" you posted since the mask can be animated for a visual all-pixel view like the GIF above. It's just a matter of fine tuning the numbers in the control panel to get a good contrast.

    This paper kind of answers a question that came to my mind at first in their conclusion:

    Among the 232 asteroids that we found, all of them were known and numbered objects except one, which is 2013 OE, a Near-Earth Object.
    2013 OE was identified only on two frames due to its high velocity.
    Based on this result and our previous experiences to find asteroids in
    this magnitude range, we conclude that only a few new main-belt
    asteroid discoveries are expected during the K2 Mission, the majority
    of the observable asteroids will be already known objects

    I'd really like to put together a movie clip of the entire M35 field with good contrast. That way, many asteroids would be seen at the same time (has that even been done before?)

    Posted

  • ajamyajax by ajamyajax in response to troyw's comment.

    A field movie clip sure seems like a neat idea. And I remembered you and Tom experimented with sonification of light curves also. What about that to assist with period recognition? Probably a fair amount of work like much of what we do here.. Edit: looks like I can get the pixel values from each frame, so might run that data thru some sort of pattern matching routine sometime.

    Anyway, here are individual frames 109-134 from your 201555556 animated GIF file. Hope it helps.

    109
    110
    111
    112
    113
    114
    115
    116
    117
    118
    119
    120
    121
    122
    123
    124
    125
    126
    127
    128
    129
    130
    131
    132
    133
    134

    Posted

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

    "Simple Math: How Fast Can an Asteroid Rotate?"

    by Michael Khan

    http://www.scilogs.eu/en/blog/go-for-launch/2010-03-09/simple-math-how-fast-can-an-asteroid-rotate

    "How fast can an asteroid rotate without being ripped apart?"

    ".. the minimum rotation period is 8403 seconds or 2.33 hours."

    "Until lately hardly any asteroids with periods of less than around 2.2 hours were known. Most rotate a lot more slowly than that. Only recently have a few fast rotators been discovered; all of these are very small."

    So my simple math is: if this asteroid is visible from BJD 1999.90 until 2000.39, that equals 0.49 BJD /25 frames = 0.0196 BJD per frame * 24 = 0.4704 hour. And assuming this is not a small asteroid, we should see one rotation OR LESS every four to five frames (edit: meaning more frames per rotation).. So as I understand this and if my math is correct, we can rule out any faster rotation here than that. And perhaps it is slowly turning also. (Yep, just trying to learn as I look here.)

    Posted

  • ajamyajax by ajamyajax

    Well, out of curiosity I reproduced a relative brightness plot using Troy's animated GIF frame pixel data here. The dip (in the spike) appears to be only an overlap of asteroid and target star data, unfortunately. And the peak is where both objects are fully visible. But it was interesting to see what charted.
    Edit: and it looks like there was a little brightness left in frame 135.

    rbp1
    rbp2

    Credit: this is a python matplotlib plot and the pixel functions used here are from the python Pillow (PIL fork) library.

    Update:

    "Ten interesting facts about asteroids"

    by Elizabeth Howell, Universe Today

    http://phys.org/news/2015-02-ten-facts-asteroids.html

    Posted

  • Martti_Holst_Kristiansen by Martti_Holst_Kristiansen in response to troyw's comment.

    Great post guys.

    "I'd really like to put together a movie clip of the entire M35 field with good contrast. That way, many asteroids would be seen at the same time (has that even been done before?)"

    I am not aware of that, but it would certainly be really kool!

    Posted

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

    And whoa, maybe an interesting 'twist' on asteroid rotation was actually observed... (The theory was mentioned earlier in an expert's quote.)

    "Unusual asteroid suspected of spinning to explosion"

    http://phys.org/news/2015-03-unusual-asteroid-explosion.html

    "They also measured a very short rotation period of 3.24 hours – fast enough to cause the object (to) impulsively explode."

    Posted