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Space Telescope Imaging Spectrograph
STAN - September 2000

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| HST Spectroscopy                      STIS/GHRS/FOS |
| STScI Analysis Newsletter            September 2000 |
|                                                     |
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CALSTIS V2.8 Released


Echelle Scattered Light Correction Software


STIS TIME-TAG Analysis

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CALSTIS V2.8 Released

Calstis version 2.8 was installed in the OTFC pipeline on August 30,
2000. Calstis 2.8 is not yet available for download, but will be in
a future STSDAS release. There were two bug fixes in this release.



Two-Dimensional Scattered Light Correction Algorithm for STIS Echelles

New software and calibration reference files are available to reprocess
STIS echelle spectra using a two-dimensional iterative deconvolution
algorithm that models and removes scattered light. The algorithm was
developed by Chuck Bowers (Goddard) and Don Lindler (Advanced Computer
Concepts), who helped design and test STIS on the ground. STScI has
implemented the algorithm in software that will likely become part
of both the archive pipeline and standard 'calstis' distribution. For
now, however, the software can only be run as a user-installed IRAF
package. Follow this link for  more information and instructions on how 
to download the package.  Note that the existing one-dimensional algorithm 
produces errors as large as 9% of the continuum in the cores of saturated 
interstellar lines, especially at the shortest wavelengths accessible
to STIS.  The new two-dimensional algorithm reduces these errors by at
least a factor of ten at all wavelengths.


STIS TIME-TAG Analysis

A recent ISR, "STIS Time-Tag Analysis Guide" (I. Dashevsky et al.), 
is available.  This document includes details on retrieving ephemeris files,
the exposure timing, preparing data for timing analysis, data
mangement, as well as answers to frequent questions from Time-Tag
users.  The examples include heliocentric and barycentric time
correction, converting the data to an image, calibrating, summing and
binning spectra, and some timing analysis, such as plotting a folded
light curve. For those that use the IRAF PROS/XRAY package for analysis
and have experienced problems converting STIS data to the required QPOE
format, there are two IRAF scripts available in the Appendix that will
do the proper conversion.


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List of Recent Preprints Online
    
 The list of preprints based on HST spectrographs data
 that used to occupy this space is now available at 
 http://www.stsci.edu/science/preprints/ for easy browsing.

 
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