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AstarVienna / ScopeSim

A telescope observation simulator for Python.
GNU General Public License v3.0
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Still inconsistencies in DIT, NDIT etc. #464

Open teutoburg opened 2 months ago

teutoburg commented 2 months ago

Setting dit and ndit explicitely, I find those values in keywords DIT and NDIT. EXPTIME is at its default value and bears no relation to DIT and NDIT (with SummedExposure it should be the product, with the hypothetical AverageExposure it should be equal to DIT). The keywords HIERARCH ESO DET DIT is at mindit, and HIERARCH ESO DET NDIT is at 90.0 (a float!), these seem arbitrary. The MJD-OBS is really DATE-OBS (format YYYY-MM-DDTHH:MM:SS).

Orignially from @oczoske on Slack.

hugobuddel commented 2 months ago

(my comments copied from slack)

Thanks for this summary Oliver. I think no-one had been paying attention to the keywords for a while. For MICADO I wrote some round-trip tests. That is, simulate something from scratch, then read in the FITS headers and recreate the ScopeSim input from that, and then recreate the exact simulation again. However, it could be that I restricted that to NDIT=1, and I recall that the AutoExposure was not used, so EXPTIME was irrelevant. This sounds consistent with the problems you describe

Note that ScopeSim is in principle instrument independent. In particular, we cannot force ESO headers in ScopeSim itself. The headers should therefore be described in the IRDB, hence the creation of ExtraFitsKeywords.