Sky Subtraction

The sky subtraction is a very straightforward step. The gfskysub task takes the sky fibers and use that to subtract the sky and the sky lines from the target fibers.

imdelete('stxeqxbrg@sci.lis', verify='no')

for sci in iraf.type('sci.lis', Stdout=1):
    iraf.gfskysub('txeqxbrg'+sci, fl_inter='no')

And we can have a look at the results.

for sci in iraf.type('sci.lis', Stdout=1):
    iraf.display('stxeqxbrg'+sci+'[sci,1]', 1)
    iraf.gfdisplay('stxeqxbrg'+sci, 1, version='1')

Notice that the sky lines are gone. There is always that bright sky line that never quite disappear, but the others have been removed cleanly.

The spectrum of a sky fiber is now just noise. No sky line, and around zero flux.

This is the spectrum of the same source as before, the one in the top-left. Now there are no sky lines in the spectrum.