desihub / tutorials

DESI tutorials
BSD 3-Clause "New" or "Revised" License
41 stars 16 forks source link

legacy imaging stamps of galaxies #93

Open forero opened 1 year ago

forero commented 1 year ago

Write a notebook with examples on how to plot stamps of galaxies given a TARGETID.

Here is a recipe from @araichoor that should make it into a tutorial

I guess you can easily get the (ra, dec) from the lss catalog, provided the id. then it s a simple bash command, e.g.:

wget -O tmp.jpeg "http://legacysurvey.org/viewer/jpeg-cutout/?layer=ls-dr9&ra=0.23790&dec=0.05840&pixscale=0.1&size=300"

and you can of course wrap that in python — and adjust the stamp properties, e.g.:

ra, dec = 0.2379, 0.0584
width_arcsec = 30
pixscale = 0.1
tmpfn = "tmp.jpeg"
size = int(width_arcsec / pixscale)
layer = "ls-dr9"
tmpstr = 'wget -O {} "http://legacysurvey.org/viewer/jpeg-cutout/?layer={}&ra={:.5f}&dec={:.5f}&pixscale={}&size={:.0f}"'.format(
    tmpfn, layer, ra, dec, pixscale, size
)
subprocess.check_call(tmpstr, stderr=subprocess.DEVNULL, shell=True)
weaverba137 commented 1 year ago

Any reason not to use requests.get here instead of calling to an external process?

araichoor commented 1 year ago

no, no reason; I just copied some piece of code I had; any suggestion you d have is certainly better!