Read integration times from FITS file headers for Compose module

[BrendanC]

Title says it all really!

Would be great if StarTools could read these details and auto-compile them into the Compose module.

Thanks, Brendan

[admin]

Thank you for this suggestion.
I never looked into this, as I assumed there was no standard way of specifying total exposure times in the FITS header. If you are aware of a standard (or defacto standard) way these are encoded, please do let me know, as I agree this would be fantastic!

[BrendanC]

I know that APP and DSS do this - seems to be a field called Temporal.IntegrationTime in the FITS metadata with the aggregate time from all the subs. The standard FITS Image Headers from APP and DSS also seem to have a field, EXPTIME, with the same value.

That's a good start!

I honestly don't know about other stacking software eg Siril, PixInsight, ASTAP, Affinity etc.

[Mike in Rancho]

I checked some ASTAP files and the total integration in seconds is also EXPTIME.

[BrendanC]

Siril uses LIVETIME for total integration, and EXPTIME for the duration of the subs.

Affinity doesn't export FITS file formats, even though it accepts them for stacking!

[admin]

Thank you for your sleuthing @BrendanC and @Mike in Rancho!
Though this confirms the problem with EXPTIME being used differently in different software, this, in combination with other fields that identify the originating software, may be enough to start work on integration time detection.

[BrendanC]

No problem! Glad it was useful. I'm trialling PixInsight too and if I ever actually manage to get anything out of it, I'll take a look and see whether it also holds this info in the header.

[admin]

I found I can - in typical cases - reconstruct total exposure time from PI FITS files by multiplying the HISTORY ImageIntegration.numberOfImages field by EXPTIME.

Expect this feature in the first 1.9 alpha release (ETA still unknown).

@BrendanC, if you are trialling PI, have a look at this table, so you get a better feel for how ST terminology relates to PI equivalents.