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I'm trying to find a few objects in the legacy survey that have been observed according to the Legacy Survey Skyviewer. I performed an svc search on http://datalab.noao.edu/sia/ls_dr7. Following that I use svc.search((ra,dec),(fov,fov), verbosity=2).to_table() where ra = 0.013398, dec = -1.112998, and fov = 0.05. The table comes out empty.

I am doing a cross-match of over 2000 objects in the end, but random checking shows that roughly half of them do not exists, when in reality all of them have been observed by the legacy survey and can be pulled up in the skyviewer. Any idea why some of these objects fail to appear?
asked Dec 2, 2019 by anonymous | 2,157 views

2 Answers

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thank you for reaching out. It appears that we have some RA values in overlap regions that ended up with a (wrong) 180 deg offset. We are correcting it as we speak. I'll comment here again when this is done.

Thank you for alerting us to the problem.

One unrelated recommendation: if you care that the search radius be always the FOV you specified, please do:

imgTable = svc.search((ra,dec), (fov/np.cos(dec*np.pi/180), fov), verbosity=2).to_table() # ra,dec,fov in degrees

to account for the cos(dec) shrinkage.

Best regards,


answered Dec 2, 2019 by datalab (11,940 points)
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The problem with the RA crossover has been corrected in the database and you should now be seeing images at the positions you reported.  Thanks for you patience and for altering us to this problem.
answered Dec 5, 2019 by datalab (11,940 points)

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