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Hubble Space Telescope
October 2013 STAN

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| STScI Analysis Newsletter (STAN) 
| Cosmic Origins Spectrograph (COS)
|
|October 2013
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In this Newsletter we provide some updates of interest to 
COS users.

Contents:



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New COS/FUV TDS Correction Produces More Accurate Fluxes
A new COS FUV time-dependent sensitivity (TDS) reference file 
(x9h1254fl_tds.fits) has been delivered for use in the HST 
Pipeline. Due to a significant flattening of the COS FUV 
sensitivity decline over the last year, data taken after 
November 1, 2012 have artificially high fluxes (up to 12% 
for most settings) and should be re-retrieved from MAST 
if the absolute flux calibration is a concern.

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New Flat-Field reference file (FLATFILE) for COS FUV
Recent analysis of the COS FUV flat field has led to an improved 
correction for some of the deepest features seen in FUV 
observations, and on September 18, 2013, a new COS FUV 
FLATFILE was delivered to On the Fly Recalibration (OTFR).  
Users, especially those with either G140L observations at both 
lifetime positions or with science interests near the edges of 
the FUVB detector (for data taken at lifetime position 2, 
i.e., after July 23 2012), should re-retrieve their data 
(archive.stsci.edu) in order to get an improved 
correction for flat-field effects.

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