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Combining Orders and Exposures to 1D
Once you have completed telluric calibration (not before!), you are ready to combine the frames into a 1D spectrum. On the "Combine" tab, select the object(s) for which you intend to generate 1D spectra, and click "Combine to 1D." This procedure will average together the individual orders from all exposures on a given object, weighting optimally by signal to noise ratio. Then the orders of the combined spectrum are merged, again with inverse variance weighting, onto a single grid. The final output spectra are stored in the redux/FSpec subdirectory by object name. The files Objname_F.fits and Objname_E.fits are the flux and 1 sigma error spectra, respectively.
The FITS headers are modified to include the standard CRVAL1 and CDELT1/CD1_1 keywords for the wavelength solution at this stage, so any program can be used to inspect the output. Within IDL, you may wish to use x_specplot, which is a convenient spectral GUI distributed with xidl.
Accessing 2D sky subtracted/Wavelength calibrated images
Firehose is optimized for point source subtraction. However it is occasionally useful to look at the 2D sky subtracted frame. This is handy wen the 1D frame has unusual residuals, or if you would like to generate your own customized routines for extracting extended or multiple sources (the pipeline *can* handle multiple point sources, but requires some hand holding).
If you would like to access the 2D data, there is an IDL function named "fire_show2D" which will return a 2D array with the sky subtracted data. This can only be done AFTER normal extraction is attempted, because local sky subtraction is performed at this time. For example, to look at the sky subtracted image of fire_0123.fits, you can call as follows from the redux directory:
IDL> skysub = fire_show2d('0123')
IDL> xatv, skysub, /block
If you wish to also look at the wavelength map, you can read this in directly from the arc file. Assuming that file fire_0123 was a long exposure with OH lines for calibration, we read in the arc solution:
IDL> logwv = xmrdfits("Arcs/ArcImg0123.fits.gz")
IDL> wv = 10^logwv
IDL> xatv, skysub, wvimg=wv
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