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Yes, one has to be careful about guessing what they probably did, because the processing was actually pretty complex, and astrophysics image processing is in ge
by mturmon 4y ago
Yes, one has to be careful about guessing what they probably did, because the processing was actually pretty complex, and astrophysics image processing is in general quite advanced. Saturation of the digital numbers coming from the detector is one consideration, but only one among many -- there is a lot going on.
The wikipedia article has a lot of details, including masking the CR's, removing some scattered light from Earth, the use of multiple color bands, and super-resolution using slightly different pointing from frame to frame. All this processing is done at the single-image level, and motivates dividing up the exposure time into chunks.
The ~340 exposures were taken over about 10 days and spread over 4 color bands. The typical integration time for one exposure appears to have been about 30 minutes.
- dredmorbius 4y agoI'm looking forward to the backstory / making of reports.
- antognini 4y agoThere is also a tradeoff where every read from a CCD introduces a fixed amount of noise (called read noise), so there is a cost to making extremely short exposures. As a rule of thumb most individual exposures on a large telescope are ~20 minutes or so for an image where the plan is to stack many exposures. But sometimes different fields have unique constraints, and obviously JWST is a different beast than ground based telescopes.