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I am concerned about whether DOPCOR adequately keeps track of subsequent velocity shifts to different apertures in a multispectrum frame. I am working with multispectrum .fits frames from the Magellan fiber spectrograph. I need to use DOPCOR to apply two different velocity shifts to the spectra. In the first pass, the value of the velocity shift depends on the aperture, so I wrote a script that calls DOPCOR independently for each aperture. For example, to shift the first three apertures I use the following three commands:dopcor input=frame.fits output="" apertur=1 redshift=1.1794 isveloc+ add+ dispers+ flux- verbose+ mode=ql
dopcor input=frame.fits output="" apertur=2 redshift=1.2734 isveloc+ add+ dispers+ flux- verbose+ mode=ql
dopcor input=frame.fits output="" apertur=3 redshift=0.9274 isveloc+ add+ dispers+ flux- verbose+ mode=qlIn the second pass I remove a relative heliocentric correction, so the velocity shift is the same in all apertures of a given frame. Thus, for example, my DOPCOR command is:dopcor input=frame.fits output=frame-shift.fits redshift=0. isveloc+ add+ dispers+ flux- factor=0 apertur=* verbose+ mode=qlThe verbose output is then usually two lines: the first states the file name and the selected apertures. The second line begins, "Correction added:", and then lists the previous correction and the new correction, then gives the sum of corrections.My concern arises because the verbose output in the second step is telling me only the correction made to the highest-numbered aperture. This leaves me wondering whether the unique velocity shifts made to individual apertures in the first pass are remembered during the second pass. I suspect so, and that the verbose output simply does not list each aperture individually, but I would appreciate reassurance on this point.Furthermore, I have noticed that if in the first pass I did not make a velocity correction to the highest-numbered aperture (say, for instance, that in my example there are four apertures in the frame), then the verbose output from the second pass has only one line, and does not give any details about any corrections carried forward from the first pass. Again, I am supposing that the corrections are carried forward but that those for only the highest-numbered aperture are listed in the verbose output, but would appreciate confirmation.Thank you,
Matt

Hello Matt,I have reviewed the code and indeed the output is misleading since it is only printed after looping over all the apertures. When you have a situation such as yours the information is not what you want. However, I believe the changes to the data and wavelength system are correct.Yours,
Frank Valdes