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Space Telescope Imaging Spectrograph
STAN - September 2002

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| HST Spectroscopy
| STScI Analysis Newsletter
| STIS/GHRS/FOS
| September 2002
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Visit the "New in the Last 45 Days" section of the STIS 
website at http://www.stsci.edu/hst/stis for new
information about STIS.

This and previous issues of the STAN can be found at 
http://www.stsci.edu/hst/stis/documents/newsletters.

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CALSTIS V2.13b Release Notes

Calstis Version 2.13b was installed in the OTFR pipeline on
2002-Sep-05. The improvements in this version include:

- Blaze shift correction
- Implementation of improved STIS NUV DARK scaling algorithm
- Implementation of time-dependent sensitivity algorithm for
  STIS NUV/FUV first-order spectroscopic modes

CALSTIS 2.13b is now available for download in the new
STSDAS release, Version 3.0, which can be found at the
STSDAS Advisories page.


Incorrect Dark Subtraction for Early 2001 CCD Data

The STScI pipeline was recently updated with a patch to fix
the temperature-dependent dark subtraction.  CCD data that
were requested from the pipeline in 2002 but originally
observed in the first 5 months of 2001 have an incorrect
dark subtraction, which will be fixed if the data are
re-retrieved using the current version of
On-The-Fly-Reprocessing.


Correction of Errors in Aperture Description Table

A revised version of the aperture description (_apd) 
reference file has been delivered to the archive. This 
corrects errors in the zeropoint offset of the wavelength 
scale for some apertures. These errors are particulary 
significant for slitless spectroscopy (about two CCD
pixels).


Monthly Offsets Disabled for Echelle Gratings

On 2002 August 05 monthly offsets were disabled for STIS
echelle observations. This operational change should allow
more accurate flux and wavelength calibration of subsequent
observations. Usage to date demonstrates that suppressing
monthly offsets for echelle spectra will not affect the
expected lifetime of the MAMA detectors.


The 2002 HST Calibration Workshop

The 2002 HST Calibration workshop will be held at the 
Space Telescope Science Institute on October 17 and 18
2002. Further details are available at the workshop's 
website.


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