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ROSAT Guest Observer Facility

IDL Update: November 1993

--by Gail Reichert

A number of changes have been made to the IDL library. For a list of the procedures that have been added, see contents.txt in the doc subdirectory, or use DOC_LIST. A specific history of changes and/or additions to the library can be found in changes.txt. These files also can be found on the GOF anonymous ftp account on, the in subdirectory rosat/software/idl.

For examples of how to run the routines, see the ROSAT IDL Recipes cookbook. This document is available electronically from the GOF anonymous ftp account on, in the subdirectory software/idl. To print the cookbook, get all of the files ending with the extension .TEX. When the .TEX files are selected, run Latex on the file (LX_IDL_RECIPES.TEX). Print the file as usual. The cookbook is being updated to reflect the changes and additions to the library.

The most important changes to the library are discussed below:

  • A procedure MAKE_EMAP has been added to calculate exposure maps over selected energy bands using instrument maps created by S. Snowden. This procedure is based on code contributed by S. Snowden and J. Mendenhall.

  • MAKE_PSF now calculates off-axis position angles of the PSPC. The normalization of the scattering term has been reduced by 30 percent to better match the calibration data.

  • MAKE_LIST now reads photon events data from MPE files. Selection by arrival time, by PI channel, and by event number now are allowed. A number of accepted time intervals can be used to select by arrival time. The procedure TIMEFILTER can be used to time-filter an existing photon list over a number of accepted time intervals. The procedure RDACTFIL can be used to read in the accepted time intervals from an ASCII file.

  • A procedure MAKE_IMAGE has been added, to accumulate images from a photon-list structure variable. The photon list can be defined, or MAKE_IMAGE can be used to create a photon list according to the specified selection criteria.

  • Procedures RSGETASP, RSGETEVR, RSORB_POS, RSGETHKB, and RSGETHKSTA and RSGET_EMAP_DATA read data from MPE format files as well as from US format files. Procedures RSASPECT , RSEVRATES, and RSORBIT are being modified.

  • The procedures RSGETNOMASP and RSGETSEQINFO have been replaced by RS_NOMASP and RS_SEQINFO, which read information from MPE format headers as well as from US format headers.

  • MAKE_SPEC has been fixed to allow spectral binning at full resolution. A photon list information structure variable (created by MAKE_LIST) now is used to pass the information about the exposure time and the number of pixels.

  • The procedure DEFGROUP has been added to define channel groupings for MAKE_SPEC. To define default response matrices for MAKE_SPEC, the procedure SET_RESPFILES has been added; users should change this procedure in accordance with the default file names at their own institutions.

  • A procedure MEX_DIV has been added to facilitate the division of PSPC images by mean exposure maps.

  • The procedures RSMAKE_PROF, RSPSFPROF, and RSPROFILE have been added to allow users to construct radial counts profiles of sources and to compare these profiles with those of the point spread function.

In addition to the new additions to the IDL library, the following procedures currently are under development:

  • A procedure that creates FITS format spectral files for use with the new version of XSPEC.

  • A procedure to accumulate images directly from photon events FITS files, without first creating a photon list structure variable. The procedure is meant to use less memory and run faster when dealing with very large files.

  • Procedures to calculate background maps, based on maps created by S. Snowden and code developed by S. Snowden and J. Mendenhall.

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