Handbook Reference
Guide
What's New with the FOC Handbook?
A great deal of effort has been put into making this version of the handbook a more complete reference for FOC. This chapter itself represents a new addition, not only providing some guidance in using the handbook, but also summarizing the latest information about the FOC. Throughout the handbook, references have been included to documentation produced by the FOC team where it is available, most of which are available on-line. New information is provided on:
- F/48 performance and availability: Problems with the F/48 kept it from being used in the last three cycles, however, recent tests have shown that the situation is finally improving so that it can be used for science again. As a result, the F/48 relay will be available for long-slit spectroscopy ONLY in Cycle 6. The latest information describing the recent performance of the F/48 can be found in the new section, "Current F/48 Performance" on page 91.
- Updated DQE: Previous versions of the handbook have included a tabulation of the overall throughput curve for the FOC+COSTAR+OTA system ("Absolute Quantum Efficiency" on page 70) which had the obscuration by the OTA secondary mirror system folded in. This, however, caused confusion when it was compared with the curves used by SYNPHOT, which accounts for the obscuration separately. Therefore, the DQE curve was re-tabulated to not account for the obscuration. In addition, the discussion in Chapter which explicitly describes how to use this curve to estimate exposure times was also updated to account for this change in convention. In addition, we have also incorporated the latest calibration results from Cycle 4 to insure that the best available sensitivity information is provided (see "Absolute Quantum Efficiency" on page 70 for more details).
- Behavior of PSF with wavelength: New information showing how the FOC+COSTAR PSF FWHM changes with wavelength has been added to "The Point Spred Function" on page 59, so that users can better understand their FOC images.
- Improved Bright Object Acquisition Procedure: As promised in Version 5.0 of the Instrument Handbook, a fully automatic procedure for acquiring bright objects is now available. This new procedure is described more fully in "Target Acquisition Modes" on page 56.
- Improved Geometric Distortion Calibrations: A new method for determining the geometric distortion of the FOC has resulted in a significant improvement of the distortion correction. This new model along with its effects on the plate scale and on our understanding of the stability of the geometric distortions are described in "Geometric Distortion and Stability" on page 87.
- Calibration Accuracies: The results of the calibration activities have always been implicitly incorporated into each previous version of the handbook, however, this time a new chapter (Chapter 11) has been added to describe in more detail the present calibration program ("Current Calibration Status" on page 118), along with the current accuracies involved in the current calibrations ("Calibration Accuracies" on page 120).
- On-line documentation: This handbook along with all other calibration products and documents produced by the FOC team have been made available through WWW browsers through the STScI pages. These pages and what they offer are described in more detail later in this chapter ("Where can I get updated information on the FOC?" on page 4).
- Updated Information on FOC simulators: The FOC Handbook has always contained a chapter describing the software package FOCSIM, which was primarily accessible only through an account at the Institute. This chapter, however, has been enhanced to describe the new software that has been added to simulate objective prism exposures (Section "Objective Prism Image Simulation" on page 109) and to describe how people can run FOCSIM through the FOC WWW pages ("WWW Form for FOCSIM" on page 107).
There are many other less significant changes throughout the handbook as well, but primarily they only served to update what was already present in earlier versions, rather than adding anything new. These updates, along with the new material listed above, combine to make this handbook the most up-to-date and complete version possible.
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