EWIMH: A Spectral Line Equivalent Width Program


Users have been reporting trouble making EWIMH work. The updated version provided here uses different HEADER KEYWORDS than the old 1994 version. Apparently the old version worked with 1D (flux vx. pixel) spectra. Newer spectra extracted with IRAF/APALL have a 3rd axis with multiple spectra (main, original, S/N, etc), and the keywords changed [if needed, you can change the keywords ewimh_clip.f looks for to match the keywords used in your spectra: see the comments with "***" in the "Get image information" section of ewimh_clip.f, and recompile (in IRAF, using fc)].

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1) Information on how EWIMH runs, installing it, and running it: ewimh.docs

2) The Fortran progam: ewimh_clip.f (original version is now ewimh_clip0.f if you want it). Note: the program looks for specific header keywords (written by APALL); if your spectra use different keywords, you can edit ewimh_clip.f and look for the "***" comments).

3) The IRAF script to run it: ewimh_clip.cl. Hint: if the continuum line is not drawn on your plots for the Ca II K line, try editing the graph lines so wy2=1.5 rather than 1.2 (it gives more room for a highly sloped continuum; this isn't usually a problem for the H-lines).

4) The file containing spectral features and wavelengths regions: ewimh.win

This version of ewimh.win is from the RR Lyrae paper. It uses variably-placed continuum bands for Ca II K, and measures it through a narrow (line 1) and wide (line 2) feature bands. It measures H-delta (line 3), H-gamma (line 4) and H-beta (line 5) using continuum bands with fixed positions).

Acknowledgements: this code is built on a core EW-fitting code written by Taft Armandroff in the mid-1980's and very kindly provided to me.

If you use this software in your research, I would appreciate an acknowledgement or citation to Layden, A.C. 1994, AJ, 108, 1016, The Metallicities and Kinematics of RR Lyrae Variables. I. New Observations of Local Stars.


Andy Layden -- Updated 2014 Oct 24