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Hello I am trying to use splot to measure equivalent widths for the optical FeII lines in SDSS spectra. The problem is that every time I try to splot a spectrum I get the message: [code:1:927efcd7c3]Warning: setting CD2_2 to 1.[/code:1:927efcd7c3]
and the wavelength axis will not show the actual wavelength values.
I am guessing this has something to do with the FITS header but I don't know which card is causing the problem.Does anybody know anything about that?

I managed to fix the problem and thought I should write that in case someone faced the same issue.The FITS header cards I had to "fix" were CRVAL1 (starting wavelength) and CD1_1 (dispersion). My problem came from using XVISTA's ALIGN to correct for the redshift. This changed the CRVAL1 card value into meters (my advisor says this is the standard FITS).
Anyhow, I used HEDIT to change CRVAL1 to Angstroms and to take the log10 of CD1_1.

The CD2_2 warning used to be an error in earlier versions of IRAF so consider yourself lucky Anyway, this is probably coming from having a 2D coordinate system which was only partially filled in.There are various ways to fix the spectral coordinate system. The most direct is to use hedit. There are keywords to tell SPLOT what units the WCS is in (I think this is BUNIT) and to tell it that the sampling is in logrithmic steps (I think this is DC-FLAG=1). I hesitate to tell you more without double checking. Since you have found a solution I will just make this reply short.Frank Valdes

Thank you Frank!