Cutout images

For a certain set of objects in the object_sdss_imaging file, we have created cutout images of the objects. There is no particular selection criterion, but if you want a particular set, we may be able to arrange to create them for you.

The image files created are in the directory for each object:

$VAGC_REDUX/cutouts/[run]/[camcol]/[field]/

and are called

cutouts-[id].fits: images and inverse variance images of the atlas image of the object, reconstructed from the reductions. HDUs 0, 2, 4, 6, 8 are the ugriz images in nanomaggies, HDUs 1, 3, 5, 7, 9 are the ugriz inverse variances
cutouts-family-[id].fits: same as previous, but for the parent of the object
cutouts-nearid-[id].fits: same as previous, but for all objects contributing to the field of the image
cutouts-irg-[id].jpg: color JPEG image of the "nearid" image
psf-irg-[id].jpg: estimated PSF in each band (ugriz) at center of object

Note that the images are reconstructed from the reductions. Since these only keep 4x4 binned images of field not assigned to objects, we add random noise with the appropriate level to each pixel not assigned to objects, in order to avoid blockiness in the images. The sum of each 4x4 region is maintained constant when we add the noise.

NYU Value-Added Galaxy Catalog