Space Telescope Science Institute  D.4 Examples Appendix E:  The NICMOS Cooling System

D.5 Types of Motions


The Phase II optional parameter OFFSET defines which type of telescope motion will be performed during a pattern. Telescope motions fall into three categories:

The available options for OFFSET are:

The use of the Field Offset Mirror (FOM) to perform dithering and mapping is an "available" (not "supported") mode of observation. The FOM is not exactly repeatable, so artifacts on the mirror may appear to move around. Observations requiring small and rapid offsets (or making observations in parallel to another instrument) may benefit from this mode. Note that the astigmatism changes with FOM offsets. Note: flat field calibration reference files are only available for the nominal FOM position.


D.4 Examples Appendix E:  The NICMOS Cooling System
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