Cutout issues with ls_dr7 (cont.d)

Question

Hey,

I recently made a post titled similarly to this one. The issue is now mostly fixed but there still seems to be one small hiccup. Mainly, it seems like the fits that were wrong last time are still slightly not square and the galaxy does not seem to be in the middle of the fits. 

ra     dec     id(optional)
0.013432752,-1.1128886,BAD
1.146787,0.84866485,GOOD

For the "BAD" galaxy, if the FOV=0.02, then the FITS looks good and square and the galaxy is in the center. If the FOV=0.05, then the FITS is not square and the galaxy is not in the center.

Please let me know what you think about this.
 

Answer 1

Hi Derrick,

this is a consequence of a galaxy being close to the edge of an individual image. If your requested FOV "spills over" beyond the image edge, the cutout will not ensure that the galaxy is in the center (since we don't do mosaicing across neighboring images), and the image may turn out rectangular.

We are thinking about providing an option to deliver a square image in any case, but with empty areas filled with e.g. NaNs.

Thank you,

Robert

Comments

Hey Robert,

That's completely fair. If that's the case, then I may go for trying to get another set of these images with a smaller FOV and hope that it is satisfactory for a majority of the galaxies.

I do appreciate the second idea. I am performing a light profile fitting algorithm for all ~2000 of these galaxies, and it would be super helpful for automation purposes if the galaxies were roughly in the center of each of their fits. Thanks for the help, Robert!