Space Telescope Science Institute   3.4.1 Target Acquisitions  3.4.3 Data Storage and Transfer

3.4.2 Typical ACS Observing Sequence


ACS is expected to be used primarily for deep, wide-field survey imaging. Important issues for observers to consider will be the "packaging" of their observations, how observations are CR-SPLIT to mitigate the impact of cosmic rays, how sub-stepping or "dithering" of images for removal of hot pixels is implemented, and how, if necessary, to construct a mosaic pattern to map the target. HRC observations and narrowband observations with the WFC are more likely to be read-noise limited, requiring consideration of optimum CR-SPLIT times. Observations with the MAMA detectors are not affected by cosmic rays or read noise, but long integration times will often be needed to obtain sufficient signal-to-noise.

A typical ACS observing sequence is expected to consist of a series of 10 to 20 minute CR-SPLIT and dithered exposures for each program filter. Coronagraphic observations will require an initial target acquisition observation to permit centering of the target under the occulting mask. Observers will generally not take their own calibration exposures. See Chapter 7 for more details about observing strategies.


 3.4.1 Target Acquisitions  3.4.3 Data Storage and Transfer
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