Time stamp for recorded airmass

Image processing, astrometry, photometry, etc.
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Patrick
Posts: 36
Joined: 01 Oct 2019, 01:10

Time stamp for recorded airmass

Post by Patrick » 09 Feb 2023, 07:00

Hello,
Can you please confirm what is the timestamp when recording airmass in FITS headers?
I assume it is the beginning of the exposure?
Regards
Patrick

fabdev
Posts: 459
Joined: 03 Dec 2018, 21:43

Re: Time stamp for recorded airmass

Post by fabdev » 09 Feb 2023, 16:18

Hello, the airmass is calculated at mid-exposure.
Instead, DATE-OBS is always the start of exposure in the FITS standard, and mid-exposure is a calculated field, as: DATE-OBS + EXPOSURE/2.
Fabio.

Patrick
Posts: 36
Joined: 01 Oct 2019, 01:10

Re: Time stamp for recorded airmass

Post by Patrick » 10 Feb 2023, 19:13

Thank you.

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