Software Packages

Profile Fitting (FITS6P)

The profile fitting program FITS6P is a descendant of the program FITS2, which was originally put together by D. Davis and D. Welty (from parts of similar programs written by A. Vidal-Madjar and W. Morton) in the summer of 1976, for analysis of UV line profiles observed by the Copernicus satellite. It is written in Fortran, and originally ran in batch mode on an IBM mainframe; it has since been significantly modified to run interactively on UNIX and VMS workstations (e.g., SUN OS, Solaris 2, LINUX, VMS). Graphics are handled by the PGPLOT plotting package (typically using an xterm or xserve window), which is available via anonymous ftp from or via the web: pgplot5.2.tar.gz (thanks to Tim Pearson).

In brief, FITS6P performs iterative multicomponent Voigt profile fits to interstellar absorption line profiles. Any or all of the column densities, line widths, and velocities of the N components contributing to the profile may be varied in the fit. Approximate 1-sigma uncertainties for those parameters are also computed. The program can handle multiplets (such as the hyperfine-split Na I D lines) -- i.e., keeping the column densities, line widths, and velocities the same for all members of the multiplet during the fit.

Further description of the program and examples of its use may be found in:

Welty, D.E., Hobbs, L.M., & York, D.G. 1991, ApJS, 75, 425,
Predicted Profiles of Ultraviolet Interstellar Absorption Lines.
Welty, D.E., Hobbs, L.M., & Kulkarni, V.P. 1994, ApJ, 436, 152,
A High Resolution Survey of Interstellar Na I D1 Lines.
Welty, D.E., Morton, D.C., & Hobbs, L.M., 1996, ApJS, 106, 533,
A High Resolution Survey of Interstellar Ca II Absorption.
Welty, D. E., Lauroesch, J.T., Blades, J.C., Hobbs, L.M., & York, D.G., 1997, ApJ, 489, 672,
Interstellar Abundances in the Magellanic Clouds. I. GHRS Observations of the SMC Star Sk 108.
Welty, D. E., Frisch, P. C., Sonneborn, G., & York, D. G., 1999, ApJ, 512, 636,
Interstellar Abundances in the Magellanic Clouds. II. The Line of Sight to SN 1987A in the LMC.
Welty, D. E., Hobbs, L. M., Lauroesch, J. T., Morton, D. C., Spitzer, L., & York, D. G. 1999, ApJS, 124, 465,
The Diffuse Interstellar Clouds toward 23 Orionis.

Versions of the program also exist for fitting QSO absorption line system profiles (with lines from different redshift systems) and for simultaneously fitting multiple line profiles with the same set of velocity components (e.g., three different Fe II lines and two different Si II lines).

To obtain the program: please contact me if you would like to obtain a version of FITS6P; currently available versions are for SUN OS 5.7 (Solaris) and for Fedora (LINUX). The tar file includes a file with complete installation instructions, as well as a file describing the program structure, variables, and flow.

Please let me know if you use the program, so that I can alert you to bugs, as they are found, and to enhancements, as they are made.

Some of the more recent development of the program was done in connection with the Local ISM Workshop project at the University of Chicago, which was supported by NASA grants NAG5-704, NAG5-1303, and NAG5-286.

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Remote Observing with IUE

IUEREMOTE is an IRAF-based package for remote observing with the IUE satellite, written by D. Welty and M. Crawford at the University of Chicago. The program's original incarnation included two main modules. One ran on a SUN workstation at Goddard Space Flight Center -- which read and decoded the data stream from the satellite, identified the image and engineering data, then packaged the data for transmission to the remote observing station (initially at the U of C). The second module, running on another SUN worstation at the U of C, read the data transmitted from GSFC, then provided quick-look analysis tools (within the IRAF environment) to allow early assessment of exposure quality for planning subsequent exposures during the observing shift.

The IRAF-based quick-look analysis tools were made available to other sites by the IUE project during the last several years of IUE operations.

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Last modified 30 Dec 2008