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Space Telescope Imaging Spectrograph
STAN - February 1999

| HST Spectroscopy                      STIS/GHRS/FOS |
| STScI Analysis Newsletter           No. 11, Feb. 99 |
|                                                     |
New HST Spectroscopy STAN Format & Content
We are continuing a transition to a new format for 
the HST Spectroscopy STAN.  At the top, an index of 
topics is listed with the web address where you can go 
to get all of the details.  Below this, short summaries 
are provided for each topic. And as always, the STAN 
will be posted on the STIS web site, where all of these 
topics will be hypertext links directing you to the 
full writeup.  All items appearing here and more are 
posted on the STIS web site, but we will only highlight 
items of particular interest or importance in the STAN.
New STIS Reference Files

Discontinuities in Rectified Spectra

Offset between CCD and MAMA Coordinate Systems

Aperture Offset Angles

New STIS Reference Files

  Many updated reference files have been installed
  in the calibration pipeline.  Among them are, 
  the aperture throughputs for all apertures (and
  corresponding photometric throughputs), photometric
  correction table for new supported apertures, as well
  as slitless spectroscopy, and improved cosmic ray
  rejection parameters. 

Discontinuities in Rectified Spectra

  An error in the interpolation method used in the 
  rectification of spectral images has caused jumps in 
  flux level in the rectified spectra.  This error will 
  be corrected in release 2.1 of CALSTIS. 

Offset between CCD and MAMA Coordinate Systems

  Observations of a target taken back-to-back with the
  MAMAs and the CCD, and with no telescope movement 
  between the individual observations should have the 
  same world coordinates in either detector.  It was 
  recently discovered that the postobservation 
  correction for the MSM deflection is currently not 
  applied. Therefore targets will not be centered in the 
  field of view, even if the target and guide star 
  coordinates had no errors.

Aperture Offset Angles 
  Each STIS aperture has a specific U3 offset angle which 
  is close to, but not equal to 45-degrees.  Precise 
  offset angles for all available spectroscopic slits 
  are available.


List of Recent Preprints Now on Line
 The list of preprints based on HST spectrographs data
 that usually occupies this space is now available at 
 the STIS web site for easy browsing.
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