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Hubble Space Telescope
February 2012 STAN

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| STScI Analysis Newsletter (STAN) 
| Cosmic Origins Spectrograph (COS)
| Space Telescope Imaging Spectrograph (STIS) 
| February 2012
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In this Newsletter we provide some updates of interest to 
COS and STIS users who will be drafting and submitting Phase 1 
HST programs over the next several weeks.  

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New ETC Release (20.1.1): Changes in the FUV sensitivity 
and new throughput curves

The COS-related changes included in the new ETC  release are 
listed in this article. Observers are encouraged to consider 
these changes when preparing their Cycle 20 phase I proposals. 

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STIS CCD E1 Aperture Positions
Observers planning to use STIS CCD spectroscopy modes are 
reminded of the usage of the E1 position and the central position 
when designing their phase I proposals.
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Common Mistakes that Can Ruin Your Data and Your Program

There are several issues related to HST program implementation 
that are entirely proposer responsibilities, which STScI does 
not have the resources to verify systematically. They are 
explained in our documentation, and user tools are provided 
to address them, but there continue to be failures caused by 
proposer oversights in these areas. Observations that fail 
for these reasons will not be repeated.

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Time Variability of the STIS FUV MAMA Dark Rate

Observers using the STIS FUV MAMA detector are reminded that 
the instrumental background for this detector is highly variable. 
The causes of this variability and ways to mitigate such high 
dark rates are explained in this article.

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CalCOS v2.15.4 Installed in OPUS

CalCOS v2.15.4 was installed in OPUS on January 12, 2012.  
Important new features for this release include a calibration 
step to correct for Y-walk and a TIMELINE extension for 
corrtag files.  A detailed list of changes related to CALCOS 
v2.15.4 can be found on the "CALCOS Release Notices" web page 
http://www.stsci.edu/hst/cos/pipeline/CALCOSReleaseNotes/notes/).

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New Photometric Conversion Tables and Ripple Tables for the 
STIS Echelle Modes

New Photometric Conversion Tables and Ripple Tables for the 
STIS NUV and FUV MAMA Echelle modes were delivered for use in 
On the Fly Reprocessing on November 8, 2011 for use with post-
Servicing Mission 4 (SM4) data. These tables reduce the echelle 
absolute flux calibration uncertainty to less than 5%; an 
improvement of 3% compared the tables previously used for 
post-SM4 data. Shifts of the echelle blaze function with time 
continue to be monitored and will be characterized in the near 
future. At this time, the shifts affect the echelle flux 
calibration less than 5%. See STIS ISR 2012-01 for more details.

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