Space Telescope Science Institute   7.3.2 HRC ACCUM Mode  7.3.4 HRC ACQ Mode

7.3.3 SBC ACCUM Mode


The SBC ACCUM mode accumulates photons into a 1024 by 1024 array, with 16 bits per pixel. The data are sent to the onboard recorder via the internal ACS memory buffer at the end of the exposure. ACCUM is the only mode available for SBC observations; the Time Tag mode of the STIS MAMAs is not available on ACS. The minimum SBC exposure time is 0.1 seconds and the maximum is 1.0 hour. The minimum time between SBC exposures is 40 seconds. Note that the SBC, like the STIS MAMAs, has no read-out noise. As a consequence there is no scientific driver for longer exposure times apart from the small overhead between successive images, described in Section 8.2.

Up to 16 SBC images can be stored in the internal buffer. SBC images can also share the buffer with HRC images and/or a single, compressed WFC image.


 7.3.2 HRC ACCUM Mode  7.3.4 HRC ACQ Mode
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