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FUSE IDL Programs

1. Introduction

A variety of IDL programs to display and manipulate FUSE images and spectra have been contributed by various members of the FUSE team, and are made available here for general use.

Chapter 8 of the FUSE Data Handbook, Retrieving and Analyzing FUSE Data, provides further description and examples of the appropriate use of these tools.

All programs listed below are available for download as UNIX tar files:

ltools_022007.tar.gz (February 2007)
fuse_idl_utilities_022007.tar.gz (February 2007)

Most of these routines require the installation of the IDL Astronomy User's Library from GSFC. Thanks to Wayne Landsman for maintaining this important resource.

2. Don Lindler's Tools (ltools) CF_EDIT allows the user to examine, manipulate, and combine the intermediate data files (IDFs) generated by CalFUSE v3. Users without access to IDL can use the "Virtual Machine" version of the program. FUSE_SCAN allows interactive manipulation of FUSE images and time-tag files. The data are displayed as an image and can be overlayed with an approximate wavelength scale. Statistics can be computed for the whole image or a selected region, and the program has a variety of tools to manipulate time-tag data. (You can even make a movie!) The program has tools to fit Gaussian emission or absorption features to or produce surface or contour plots of small regions of the image. FUSE_ANALYSIS is an interactive viewer for calibrated FUSE data. The program can simultaneously display spectra from all four detector segments for a single exposure. In addition to plotting the calibrated results, it will display regions of the raw image from each detector for comparison. FUSE_REGISTER is an interactive tool for registering, scaling, and coadding calibrated FUSE spectra. The routine allows you to register and coadd multiple exposures for the same channel, or to register, scale, and merge data from multiple channels. (Warning: This is not appropriate in all cases!! See the FUSE Data Handbook for more details.) Do we want a link to a specific section of the handbook???.

A general-purpose plotting tool used by the FUSE IDL data-analysis widgets. It allows the user to overplot up to 10 plots. It can be used as a stand-alone widget or called from another widget. A general purpose tool used by the FUSE IDL data analysis widgets for creating data masks of 1-Dimensional data. It can be used as a standalone widget or called from another widget.

An interactive least-squares multiple Gaussian fit routine. An interactive tool for continuum normalization of a spectrum. The tool can be used as a stand-alone routine or called from another widget. A spectral-feature analysis tool using the algorithms of the International Ultraviolet Explorer Feature routine. It can be used as a stand-alone routine or called from another widget.


CF_EDIT is described in the CF-EDIT Users Guide (in PDF).

FUSE_REGISTER is described in a document dated July 2002 and retrievable in one of two formats:

PDF file (150 KB)
gzipped (compressed) PDF file (110 KB)

The other routines are described in a document dated February 2001:

PDF file (in PDF, 450 KB)
gzipped PDF (410 KB)

3. Other FUSE Tools (fuse_idl_utilities)

This program is an IDL widget program for displaying 2D images. The original program, called, was written by Aaron Barth at CfA. The program was modified for FUSE, precipitating the name change. The program has the look and feel of an early version of SAOimage.

Documentation for the following programs can be found in the .pro files themselves.

This is a utility program which will read FUSE format raw FITS files for the purpose of turning them into 2D images for display. It automatically determines the file type from the file header. It is used by some of the other programs provided here.

This program reads in a raw ttag FITS file and plots the count rate as a function of time.

This program reads in a FUSE raw FITS file and makes a gray-scale image plot of the detector segment for printing. /

These programs will plot extracted spectra from all 4 detector segments onto a single sheet of paper. Use for spectra created from versions of the pipeline before 3.0. Otherwise use

wfusehist, wfusettag

These programs write FUSE HIST or TTAG files.

4. Other Contributions

John Grimes has written an IDL routine to modify the wavelength arrays of the LiF and SiC target spectra within an individual IDF. It is useful, for example, if you want to align the spectra from individual exposures to a common wavelenth scale before combining their IDFs. The program,, can be called from the command line using the Perl script

Here's a little IDL script to identify times when a bright target is out of the aperture. It uses the count-rate array in the timeline table of the IDF to construct a count-rate histogram, then rejects times when the count rate is more than 3 sigma below the mean. For such times, the jitter bit is set in both the timeline table and the photon list. The program is called

5. Having Trouble?

Don Lindler's subroutines have been updated to work with IDL 6.3. If you are getting error messages, try re-installing them.

If you are unable to display spectra when running fuse_register or cf_edit on a Mac or PC, try installing the latest versions of the astron and ltools libraries. Another trick: add these lines to your file.