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Wide Field Camera 3 Instrument Handbookfor Cycle 22 > Chapter 7: IR Imaging with WFC3 > 7.2 Specifying an IR Observation

7.2
In the HST proposal system, the parameters for an IR observation available to General Observers are:
1.
Configuration: always WFC3/IR.
2.
Mode: always MULTIACCUM.
3.
Aperture: must be specified; see Section 7.4.4 and Section 7.4.5 for the dimensions, location, and reference point (target placement) of the full array and subarray apertures.
4.
Spectral Element: must be specified for each exposure; see Section 7.5.
5.
Optional Parameters: in the IR channel SAMPSEQ specifies a predefined sequence of times at which the detector is read out, and NSAMP specifies the total number of readouts (and thus the total exposure time); see Section 7.7. SAMPSEQ and NSAMP are required for IR observations.
6.
Special Requirements: see the Phase II Proposal Instructions for details of Special Requirements related to the timing of visits and for dithering and mosaicking. Also available is the exposure-level Special Requirement POS TARG for offsetting the target from the default reference point of the aperture (see Section 7.4.3 for a discussion of the IR channel coordinate system).
7.
Number of Iterations and Time per Exposure: in cases where two or more identical exposures are desired, the Number of Iterations may be set to 2 or more. In the IR channel, the Time per Exposure is fixed by the combination of SAMPSEQ and NSAMP (see item 5 above) and thus is not specified separately. Through various combinations it is possible to select times per exposure ranging from 2.93 to 2756 s (for readouts of the full detector array; considerably shorter exposures are possible using subarrays).

Wide Field Camera 3 Instrument Handbookfor Cycle 22 > Chapter 7: IR Imaging with WFC3 > 7.2 Specifying an IR Observation

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