One or two asteroids.
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by Budgieye moderator
One or two asteroids? It looks like two , but they seem to be going in different directions, since the green and blue are reversed. This seems unlikely, since most of an asteroid's apparent motion is due to the movement of the Earth. and all asteroids will be moving in the same apparent direction.
There are 2 blue and 2 green images taken. I wonder how far apart in time they are. On DECaLS viewer, click on filters, and a list of images should appear on the screen,
Blue images
Exposure 433216, g band, 70.0 sec exposure time, seeing 1.39 arcsec, file decam/CP20150407/c4d_150417_024855_ooi_g_v1.fits.fz
Exposure 433223, g band, 70.0 sec exposure time, seeing 1.38 arcsec, file decam/CP20150407/c4d_150417_030051_ooi_g_v1.fits.fz
Green images
Exposure 433217, r band, 75.0 sec exposure time, seeing 1.30 arcsec, file decam/CP20150407/c4d_150417_025038_ooi_r_v1.fits.fz
Exposure 433222, r band, 76.0 sec exposure time, seeing 1.21 arcsec, file decam/CP20150407/c4d_150417_025910_ooi_r_v1.fits.fz
All 4 images were taken on the same day 150417, or April 17, 2015
02:48:55 - blue
02:50:38 - green
02:59:10 - green
03:00:51 - blue
the images were taken in the order blue , green,. ..., green , blue
So it looks as if this is the same asteroid images 4 times over 15 minutes.
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by CSA00
1237648722307121547 1237648705115128223
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by Budgieye moderator
Yes, these are asteroids in SDSS, where the 3-coloured images are taken within 5 min of each other.
see
8.3 asteroids, ice worlds http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000wrb?page=8&comment_id=53d8bc1e0d43f776b00010bb
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by CeciliaB
Thanks Budgieye for looking into this!
I suppose it's not possible to explain why the two images of the asteroid have the green and blue colours reversed and seem to be going in different directions. What a mystery!
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by Budgieye moderator
It is 4 images, taken as it moved in a straight line. I have no idea why the filters were in the order blue , green, green blue, but there is sure to be a good reason.
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