FITS header does not have offset information

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bellavia
Posts: 18
Joined: Mon Nov 27, 2017 2:15 am

FITS header does not have offset information

Post by bellavia » Sat Aug 04, 2018 3:31 pm

Hi,

I have two ZWO ASI 183 cameras. The MM Pro and the MC Pro.

They are amazing. (well, except for the amp glow, but that is another topic).

The issue I am currently having is that the offset used in any image is not shown in the FITS header.
This is important to me, as I am trying to maximize the dynamic range, and I set the offset, for each gain, to be very close to zero, but without clipping (so around 25 to 250 ADU's in 12-bit, from 0 gain to 270, respectively, or "5" to "50" per the ZWO offset numbering system).

It would be really nice if the offset info could be added, because I am stacking some older images, and now do not know which dark frames to use, as I have many sets in my dark frame library, at various gains and offset, and I do not know what offset my light frames were at, and there is no way to determine it from the files. Had I known, I would have put that into the filename when saving.

Any help is appreciated.

Thanks ZWO!

Steve

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Sean.Wang
Posts: 713
Joined: Mon Apr 24, 2017 10:08 am

Re: FITS header does not have offset information

Post by Sean.Wang » Mon Aug 06, 2018 3:40 pm

Thanks for feedback, we will check it!
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