FOC Cycle 6 Calibration Plan
f/48 Special Calibrations
The recent successful operation of the f/48 relay has prompted some effort
to characterize the long-slit spectrograph and detector in support of f/48
long-slit spectroscopy. These calibration proposals will provide some
measurements of the slit location, detector sensitivity, slit throughput, and
geometric distortion with the expected accuracies summarized in the
f/48 calibration summary
[Postscript, 55kb].
Calibration Summary
The performance of the FOC+COSTAR system has been characterized in
detail using a combination of ground-based and in-flight tests. After
COSTAR deployment, an extensive calibration program was carried out (SMOV)
to describe the performance of what could be considered, to all intents
and purposes, a new instrument. At that point, the scientific program was
enabled. The Cycle 4 calibration program then completed this initial
effort and fully characterized the FOC+COSTAR performance. In Cycle 6,
we are in a routine situation, and our calibration program is divided
into two parts:
- a set of monitoring tests, whose aim is to maintain the calibration
level previously achieved (e.g. pointing accuracy, geometric distortion,
flat fields), or
- to discover possible variations in performance
a number of dedicated tests designed to maximize the scientific output
of the instrument.
These tests were designed after having carefully reviewed the observing
proposals to be executed during the current cycle, and would, for example,
provide accurate PSFs and check the detector response at certain wavelengths,
or characterize special capabilities not previously calibrated.
In the calibration summary table
[PostScript, 55 kb], we provide a list of the calibration tests which are
being performed in Cycle 6, with their objective outlined. An extensive
calibration program has been designed, after checking all the individual
requirements, to ensure that the best science is achieved with the FOC.
- The Routine Calibration Programs
- The routine calibration programs are designed to monitor those aspects of FOC
performance that are believed to be subject to time variation. Typically,
observations are made at 3 month intervals to verify that the performance
has not changed significantly, and then warn users if a significant difference
is found.
- The Special Calibration Programs
- The special calibration programs are designed to offer a more detailed
calibration of modes or observation types and represent a class of calibration
observations that may be executed once with the results expected to be valid
over a long time base. Previous special calibrations, as well as monitoring
programs, have resulted in calibration accuracies as discussed in Section 11.2
of the FOC Instrument Handbook.
Should your program require calibration accuracies that are not obviously
satisfied by the values listed in the FOC Handbook, then you should contact
STScI for guidance. Individual GO programs requiring special calibrations
must directly request these observations as part of their Phase I proposal.
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