Difference between revisions of "Using QL outputs"

Revision as of 10:24, 22 December 2016

Overview

The QL Tool produces quick-look products, but there are some straightforward steps allowing users to use these as a starting point for their science quality reductions

Important Notes

In going from the raw 2D images to the 1D extractions produce by the QL Tool:

• The x axis is flipped so that increasing wavelength runs in the same direction as increasing x
• The spectra are then trimmed to remove overscan, etc.

The exact values for these are stored in: /usr/local/etc/qlgui/pars.json

"badMax0": 98,

"badMin1": 2145,

in python 0-based numbering.

i.e. in python, to reproduce the same transformation, one would do:

from astropy.io import fits

im2D = fits.getdata('image.fits')

im2D = im2D[:,-:] # flip x

im2D = im2D[:,98:2145] # trim

fits.writeto('outimage.fits',im2D)
This image could then be used for a fresh extraction using IRAF or the user's preffered package, and will be one-to-one pixel aligned with the [approximate] WLC from the 1D extracted arc.

In IRAF, the equivalent would be:
imcopy a0361665[-*,*] test.fits
imcopy test.fits[99:2146,*] out65.fits</br > [Note the 1-based indexing]