iraf.net

I've been trying to compare a few spectra of the same object taken on different observing nights to see if sky subtractions varied and how they were affected by the sensitivity functions (they're at different wavelengths, so they behave differently at the ends of the spectra).Specplot and Spectool do a good job of overplotting, but specplot can't measure fluxes (equiv. widths) or switch between spectra very effectively, and overplotting in color is difficult if I want to stay in interactive mode. Spectool does a better job of that, but I can only measure the equivalent widths of marked lines.First, spectool has a tendency to crash on me. I mark one or two lines with 'm', then try to measure their eq. w's with 'e', and sometimes it works, then after a few tries it freezes and becomes unrecoverable. Interrupt, shift-I in the spectool window, doesn't work, neither does control-C in the xgterm. Anyone know why this is happening or what I can do to fix it?Second, is there any way to manually measure equivalent widths? Since the continuum fit isn't perfect, I need to measure high and low continuums to give measurement error. Also, in regions with bad sky subtraction where the lines are of scientific importance, I would like to be able to measure at least part of the line to put a lower limit on the flux value. On a related note, I tried plotting the 'sigma' of a few spectra blindly, not knowing what it is, and it always gives me a segmentation fault.Thanks,
Adam

Well, this reply is a little late but you can manually measure equivalent widths in splot with the 'e' command. the trick lies where you hit 'e' because that determines the continuum level, where most of the error comes from.I also find spectool not that useful in measuring spectra... the marking features and measuring never seems to work quite right.

---

The re-born Mac IRAF web site: http://macsingularity.org