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Hello.

I have been given the task to measure the equivalent width of a spectra.
But I also need to use a continuum first and then measure ew by using 'e'.

After I get the continuum using 'onedpsectra', I then super impose the spectra on the continuum. The continuum shows in white while the spectra shows in red.
The problem is the continuum does not touch the spectra at the points where I want to measure the ew because it's far from it.

Can someone please help me with this?
If needed, I can upload a .fits file of my spectra (along with the continuum) and also a pdf document explaining my problem on the ftp website.

Thank you.

Adnan

I assume we're talking about using SPLOT here? If so, the 'e' keystroke position defines the continuum whether or not you have another continuum overplotted so just position the cursor where you think the continuum ought to be. It will use a line between the two points as the continuum when calculating the EW, subtracting the continuum to flatten the spectrum is a totally separate step.

Thank you for your reply.

Yes it is using SPLOT. I don't think I have explained it well. Can I send you a pdf file explaining what I did along with the image file (on ftp) I want to calculate equivalent width for?

Sure. If the files are small you can email directly to fitz-at-iraf.net or else upload to the anonymous ftp at ftp://iraf.noao.edu/pub