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Hubble Space Telescope
August 2014 STAN

| STScI Analysis Newsletter (STAN) 
| Space Telescope Imaging Spectrograph (STIS) 
| August 2014

In this Newsletter we provide some updates of interest to 
STIS users:



A 10% increase in the STIS CCD Readnoise at GAIN=1

Recent monitoring of the STIS CCD readnoise for GAIN=1 
has revealed a sudden increase of roughly 10% to 6.25e- 
per read.  For most users, this impact will be negligible, 
with the exception of science programs that require multiple 
reads of objects with low signal-to-noise in individual reads 
(such as high contrast imaging or spectroscopy of objects 
with highly wavelength variable spectral energy distributions).  
The STIS team is in the process of updating the read noise 
values used in both the ETC and CalSTIS.  There will also be 
continued investigation into the potential reason for this increase.  
PIs of pending STIS CCD programs that use GAIN=1 should 
verify that their science programs are not adversely affected 
by this change.  If so, they should immediately contact their 
program point of contact or the help desk.

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