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Hubble Space Telescope
February 2015 STAN

| STScI Analysis Newsletter (STAN) 
| Cosmic Origins Spectrograph (COS) 
| February 2015

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



Move of COS FUV Spectra to Lifetime Position 3 and Revisions
to CalCOS to Support Spectral Extraction at the New Position

On February 9th, 2015 the COS FUV spectra were successfully
moved to Lifetime Position 3 (LP3)  (except for G130M/1055
and G130M/1096 which remain at Lifetime Position 2). Initial
test exposures using the new position show that the instrument
is performing as expected. The spectral and spatial resolution
at the new lifetime position are expected to be within ~15% of
those at Lifetime Position 2. Small changes to the wings of the
line spread function are predicted; new LSF models have been
computed and will be made available to users once they are
validated by calibration observations at the new lifetime position.
In the coming months LP3 calibration data will be obtained and
calibration reference files will be updated as needed. The LP3
move is transparent to all users.

The new LP3 spectral location (~6" below LP2 and ~2.5" below LP1)
is sufficiently close to gain-sagged regions at LP1 that a
revised algorithm is needed to ensure good quality spectral
extraction. We provide an overview of how this new extraction
algorithm works, its strengths and limitations, and also describe
new informational columns provided in the x1d files. More
information about the new extraction algorithm will be provided
in an upcoming update to the COS Data Handbook, planned for
later in 2015.

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