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Hubble Space Telescope
September 2010 STAN

| STScI Analysis Newsletter (STAN) 
| Cosmic Origins Spectrograph (COS)
| Space Telescope Imaging Spectrograph (STIS) 
| September 2010

In this newsletter we summarize import updates to the calibration
pipeline and calibration reference files of COS and STIS.


New Time-Dependent Spectroscopic Sensitivity Reference Files 
Delivered for COS and STIS

As part of routine monitoring of spectrophotometric white dwarf standard 
stars, a time-dependence to the spectroscopic sensitivity of both COS and 
STIS has been characterized.  For COS, new reference files have been delivered 
and are now routinely used in pipeline processing of data.  For STIS, 
existing reference files have been updated based on trends observed in 
Cycle 17.


Revisions to the Data Quality Flags for Calcos

The Data Quality flags used by calcos have been redefined, and for the FUV 
channel, areas of the detector shadowed by grid wires are now excluded when 
creating the x1dsum spectra.


COS G140L/1280 Wavelength Calibration Warning

The zero point of the wavelength scale for the new COS FUV G140L/1280 mode 
is likely to be off by a few angstroms. Analysis to better characterize the 
wavelength range is on-going and better calibration is expected soon.


COS Calibration Updates

After the Cosmic Origins Spectrograph (COS) was installed on-board the
Hubble Space Telescope (HST) in May 2009, it underwent an extensive 
calibration and characterization check-out during the Servicing Mission 
Observatory Verification (SMOV) period.  The results from this program were 
used to update reference files and make changes to CALCOS, the COS data 
processing software. This article discusses enhancements to the standard 
data products.  For the FUV, these include excluding detector regions 
affected by wire shadows when creating x1dsum files, pulse-height 
filtering to reduce background features. For the NUV channel, vignetting 
corrections have been incorporated into the flat field file, and for both 
channels, improvements have been made in the wavelength scales, flux 
calibrations, and data quality flagging.  Furthermore, additional data are 
included in the FITS products to allow users to perform customized 


Recent COS and STIS Instrument Science Reports

Since HST Servicing Mission 4 a number of Instrument Science 
Reports (ISRs) have been published which characterize the behavior 
of COS and STIS. We provide a complete list of COS and STIS ISRs 
published since SM4.

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