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Space Telescope Imaging Spectrograph
STAN - December 1998

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| HST Spectroscopy                      STIS/GHRS/FOS |
| STScI Analysis Newsletter           No. 10, Dec. 98 |
|                                                     |
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New HST Spectroscopy STAN Format & Content
 
We are beginning a transition to a new format for 
the HST Spectroscopy STAN with this issue.  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 before, 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.
 
 

Change of Supported Apertures for E230H
 

Exposure Time Incorrect in Interrupted STIS Exposures
 

CALSTIS 2.0 Released
 

Improved Cosmic Ray Rejection Parameters for STIS
 

New STIS Reference Files
 

CCD Hot-Pixel Alert for STIS Spectroscopic Observations
 

STIS Fringing Tutorial Now Available
 

GHRS `poffsets' Task not Reliable for Weak Data
 

FOS Paper Products Now Support Spectropolarimetry 
 

FOS/BL Zero-Point Wavelength Correction Description
 

List of Recent Preprints Now on Line
 
+-STIS------------------------------------------------+
 

Change of Supported Apertures for E230H
 
 A change has been made to the supported apertures 
 for the E230H grating for Cycle 8 which could 
 affect your unexecuted Cycle 7 visits as well.  
 We bring this to your attention now should you 
 desire to make a change to your Cycle 7 program.
 

Exposure Time Incorrect in Interrupted STIS Exposures
 
 When a STIS exposure is interrupted (i.e. for a 
 guide star loss of lock), the take data flag 
 (TDF) goes down, which prevents STIS from 
 obtaining data.  There are consequences of this 
 event and a procedure to fix the problem.  
 
 

CALSTIS 2.0 Released
 
 A new version of CALSTIS (version 2.0) has been 
 released and is now used in the pipeline 
 (effective November 10, 1998). There are major 
 changes, a number of additional enhancements and 
 minor problem fixes, and updated tools released 
 with this version.   
 
 

Improved Cosmic Ray Rejection Parameters for STIS
 
 The calstis pipeline includes a step to 
 automatically reject cosmic rays in CR-SPLIT CCD 
 exposures.  A new parameter table has been 
 installed to optimize the rejection.  
 
 

New STIS Reference Files
 
 Many updated reference files have been installed
 in the calibration pipeline.  Among them are, 
 the filter throughput for the UV imaging 
 modes, new "PFLATS" for the MAMA detectors, and a 
 new "LFLAT" for the FUVMAMA. 
 
 

CCD Hot-Pixel Alert for STIS Spectroscopic Observations
 
 Dithered images can be used to cure most of the 
 hot pixels in STIS CCD imaging observations.  
 However, removing hot pixels from spectroscopic 
 observations can be more involved, and hence 
 spectroscopic observations need some special 
 consideration.
 
 

STIS Fringing Tutorial Now Available
 
 There is a new ISR of particular interest for
 those people working in the Near-IR.  ISR 98-29
 will show you how to use the IRAF defringing
 tasks with your data.
 
+-GHRS------------------------------------------------+
 

GHRS `poffsets' Task not Reliable for Weak Data 
 
 The `poffsets' task, usually used with GHRS 
 FP-SPLIT data, determines shifts.  The cross 
 correlation technique to determine wavelength 
 offsets between individual spectra from spectral 
 features (in default mode) is not reliable for 
 weak or noisy features.   
 
+-FOS-------------------------------------------------+
 

FOS Paper Products Now Support Spectropolarimetry
 
 The paper product task 'pp_dads' has been enhanced 
 to support spectropolarimetry data; the upgrade was 
 part of the STSDAS release 2.0.2.  
 

FOS/BL Zero-Point Wavelength Correction Description
 
 Zero-point shifts in FOS/BL and FOS/RD wavelengths 
 occurring between launch and de-commissioning are 
 discussed and relevant Instrument Science Reports 
 noted.  Information on an IRAF/STSDAS cl script to 
 be used to correct the wavelength files (.c0* 
 files) for any FOS/BL (non-PRISM) observation is 
 also provided. 
 
+-Spectrographs---------------------------------------+
 

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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