UKIDSS - SDSS image mismatch?
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by
vrooje
admin, scientist
Yesterday, @planetaryscience pointed out that for this object, the UKIDSS sky patch doesn't match up with what SDSS says should be there:
While it's true that UKIDSS is a bit less deep than SDSS, it should still have seen this big group of red galaxies. And the stars don't line up between the images, even under various kinds of mirroring/rotating to account for different telescope orientations and so forth. What's going on?
Edd E. has been looking into this, and found out that this group of galaxies lies at a point in the UKIDSS images where the telescope coverage makes an "L" shape:
And at points like these, the algorithm that is supposed to either correct for edge-of-coverage effects or skip the source altogether, well... breaks. It picks one of the corners of the image instead.
We're working on fixing this, and we're pretty sure that at least 97% of the images are fine, but the first step is just to find the images. We've got the computers working on doing that for us now that we know what to look for, but if you see any more like this, feel free to bring it to our attention with a tag like #SDSSmismatch or similar.
In the meantime, thank you for your patience and your sharp eyes!
-BrookePosted
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So should we deliberately look for mismatched images, or just happen to come across them because the computers can do it so much more quickly?
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Found:
Searched: AGZ0007o1a to AGZ0007onz (end of UKIDSS images)
540 galaxies looked at (2.59% errors, just as you predicted 😮)
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vrooje
admin, scientist
Wow, nice finds! I will pass these on. Don't worry, I think the computers will be able to find the rest now that we have so many examples of what to look for. But if you do happen to come across one, feel free to tag it. Thank you!
-Brooke
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Thanks! When you're done finding them, could I see the results by any chance? I'd like to do some further testing.
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vrooje
admin, scientist
Yes -- I'll ask Edd to post it (or send it to me so I can) once he's finished. 😃
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lucycao1989 just found another mismatched image, AGZ0007cbu and I found AGZ000797d , AGZ0007fuq , and AGZ0006b82, and john.talbot.astro found AGZ0006y64
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by
zutopian
http://talk.galaxyzoo.org/#/subjects/AGZ00078j6
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AGZ0006w9c found by SolOmniaRegit
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by
williamaskew
i have found a lot of these.
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by
Edd
scientist
Hi
Got my hands full with a few bits right now but should get results uploaded for the team soon and I will be happy to share the list - especially since it may help us clean the sample further.Posted
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What exactly will you do when you find them? Will you delete them, leaving a sort of hole in the classification catalog, or will you be correcting the errors and putting the correct images in place of the errored ones? if you do the latter, will you keep the comments on the images with errors, or will they be deleted? Just wondering...
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by
Edd
scientist
We'll probably leave things in place on the site, and exclude them from the final published catalogue (and of course other science results). There shouldn't be a large proportion, and that would leave us some flexibility in exactly how to make the cut later on - it's the most conservative way to do things in other words. If the plan is any different I'll try to remember to drop a note back.
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GLambourne found AGZ00072qn
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John.Talbot.Astro found AGZ00078cl and AGZ0006wms
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Ncameron found AGZ0007fe6
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I found AGZ0007ebi
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and also found AGZ0006x4m
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John.Talbot.Astro found AGZ0006lwy
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I found AGZ0006i6t
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Nickverelst found AGZ0006q7l
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Mick Rochon found AGZ00065wi
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NHK8652 found AGZ00076sa and John.talbot.astro found AGZ0007mnv and AGZ0006y7t
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Notes found AGZ00078vz
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Suelaine found AGZ0006p6x
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by
KWillett
scientist, admin, translator
You're all doing a heroic job on this. Thanks!
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Thanks! 😄
i found AGZ00077la
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ChrisMolloy found AGZ0006vwu
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I found AGZ0007leo
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losltens found AGZ0007243 and I found AGZ0007bkn
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seems the code is keen on insulting me.
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List of SDSSmismatch galaxies found so far:
(AGZ00065um beginning of images)
(AGZ0007onz end of images)
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zutopian
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