30 Second Exposures Camera Inputs Stubbs/Hascall 1

Overview There is a performance benefit, in particular from the longer read time. The benefit is much bigger at the observatory level A specification change is significantly more work than a capability demonstration, the rest of these viewgraphs assume demonstration Changing the camera specification from 2x15 second exposures to 1x30 second exposure requires significant effort in tracking down all locations in all documents that depend on 15 second exposures. Capability demonstration could be done with a small addition to test time depending on the level of that demonstration. What ranges of read time should the camera consider? The read time is not completely hidden in the slew for short slews and deep drilling Other technical side effects are very low Inputs from Chris, Tony, Mike, Martin, Vincent and Stuart 2

Benefit Details Reduced number of images by ~2 Raft power reduced (~100W for the entire camera based on current power budget inputs, few percent effect for the camera, 5ish percent for the cold plate) DAQ 2 day store reduced (low cost difference) Shutter open/close count reduced Maintenance advantage, difficult to quantify at this stage in development Small power benefit (5 W based on current power budget inputs) Increasing the read time will improve crosstalk and read noise although power consumption would rise taking back part or all of the ~100W reduction.

Other Details Camera readout sequences are based on a 2 second readout. The readout is not parameterized while the read time is. Week or 2 effort to generate new sequence with a longer read time and demonstrate performance (duration depends on how thorough the demonstration needs to be) Additional impacts if two readout times need to be maintained, with some solutions providing advantages for operations (new configuration required vs parameter to sequencer) The dynamic range would shift, but since the camera requirement is set relative to the limiting magnitude the camera requirement is not affected. The derived full well specification would not change. Minor wording changes needed since the spec calls out a 15 second exposure Several requirements call out a 15 second exposure (exposure duration knowledge, wavefront sensor noise, guide sensor positional stability, …) and would need rewrite. Image latency requirements need review if the read time is extended. For example the wavefront sensor latency is within 3 seconds after the beginning of the readout.