Why Legacy DR9/DES DR2 images are mirrored?

Question

For example, the cutouts of a galaxy (with coordinates RA = 181.1970, DEC = -2.719) are mirrored when comparing with Legacy Survey Sky Viewer (https://www.legacysurvey.org/viewer?ra=181.1970&dec=-2.7198&layer=ls-dr9&zoom=15).

Example from cutout service: https://datalab.noao.edu/svc/cutout?col=ls_dr9&siaRef=legacysurvey-1811m027-image-g.fits.fz&extn=1&POS=181.1970,-2.719&SIZE=0.1,0.1&preview=true

Answer 1

Thanks for reaching out. This is how the WCS is defined in LS/DES. The Legacy Survey viewer does the more standard conversion afterwards. Please see also a previous user question about this (Question 2) in: https://datalab.noirlab.edu/help/index.php?qa=486&qa_1=image-cutout-service-downloading-full-image-specified-size&show=486#q486