FITS Keywords

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Forum_2017
Posts: 275
Joined: 10 Dec 2018, 16:23

FITS Keywords

Post by Forum_2017 »

Hello,

Viewing the Fits header, the FITS Keyword EXPTIME is understood. Are you able to advise the meaning/purpose of the word EXPOSURE?

Regards,

Patrick.

Forum_2017
Posts: 275
Joined: 10 Dec 2018, 16:23

Re: FITS Keywords

Post by Forum_2017 »

Hello,
they are the same key: Time of exposure in seconds.

EXPOSURE is the newer keyword.
EXPTIME is an old keyword. Astroart will write both for some time.

Edit: in the draft of the FITS standard 4.0, the new keyword will be "XPOSURE" not "EXPOSURE" which just like "EXPTIME" is a non-standard keyword.

Edit2: EXPTIME will remain as main keyword until an official standard will be defined.

Forum_2017
Posts: 275
Joined: 10 Dec 2018, 16:23

Re: FITS Keywords

Post by Forum_2017 »

Thank you for that.
I am currently investigating IRAF where the 'old' keyword can be a required parameter, looked for in an image header. However, this change may be overcome by use of an Instrument Translation File (instruments NOAO.IMRED.CCDRED for those interested).
Regards,
Patrick.

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