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Question about FITS Header Entries

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Hi,

EKOS writes some entries in the FITS header. Is there any chance adding entries from connected devices, too ?
I know for example the CCD Camera snoops devices, but is not going the add the values in the FITS Header. In addition some device types are even not be selectable as snoop devices (e.g. environment)

I would be nice doing so, because than you could save all the context information of an image inside the FITS file (Focuser position, outside Temp, Sky Quality, Dew etc.) This enables to make some test and calculations later (e.g. focuser positions over temp and filter)

Any ideas ?

Michel
The following user(s) said Thank You: Juan Daniel
4 years 6 months ago #43732

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This could be great feature. I have just purchased automatic focuser (AF3) with temperature probe and I am bit disappointed with Ekos as it is not able to save the measured temperature into FITS header.
3 years 10 months ago #54974

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FYI, while not changing FITS header fields, I did submit a code update yesterday for updating temperature and HFR in focus logging. I don't have a focuser temp sensor, but many of us do have Pegasus PPB, V2, or other weather temperature sensors that can now be properly captured in focus logging (all focus algs). Also added is a separate CSV friendly autofocus log. A header line + comma delimited data fields (one line per successful autofocus) are provided. An example autofocus log is below:

date, time, position, temperature, filter, HFR
2020-06-01, 15:06:53, 42578, 15.0, Red, 1.119
2020-06-01, 15:07:53, 42443, 15.0, Red, 1.19

If approved, these changes will broaden supported temperature sensors for focus logging, and provide better support for correlating temperature, filter, HFR, and focuser position relationships. The code is awaiting approval/merge. The work is related to this other post:
www.indilib.org/forum/ekos/6901-how-does....html?start=24#54331

Cheers, Doug
The following user(s) said Thank You: Ferrante Enriques
3 years 10 months ago #54978

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Hi Doug,
a good idea, too. Ideally I would store all context information about and image in the image file and nowhere else, because this data is linked 1:1 togehter.
Michel
3 years 10 months ago #55055

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Hi Michel, I (almost/pretty much) agree. From one perspective, having all context in the FITS header is really convenient. For example, the archive AstroDom already supports FITS header keywords and this would make focus performance correlation/evaluation easier (a pet peeve for me lately). Ferrante (AD developer) wouldn't need to think about how to import and correlate a separate, focus specific CSV file to capture that info in the image archive DB. On the other hand, it does seem just a bit awkward to include focuser position (for example) in an image header; the info relation doesn't seem quite as compelling as for other fields (HFR, ambient temperature). So, I can see it both ways. Given how much cruft is in the typical FITS header of most professional observatories, having one or two slightly less compelling entries shouldn't really cause any problem... I do think having a separate focuser log is good because that log can be directly graphed to create temperature, HFR, and position correlation information that is independent of any specific image. It wouldn't be very convenient to have to pull this out of headers separately. So I see both ideas (header and separate log) as complementary.
Cheers, Doug
Last edit: 3 years 10 months ago by Doug S.
3 years 10 months ago #55061

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Adding to that, the FITS standard does allow for adding custom keywords but one should be cautious with that. If Ekos adds keywords A and B and another imaging system adds similar keywords but calls them C and D then it would become very hard for applications that process the FITS headers to support all keyword names and formats. I do not necessarily mean to imply to not add additional info to the FITS header of an image but merely that if such an addition would add valuable info, that the discussion about it should be held on a much wider scale that only this forum.

Clear skies, Wouter
3 years 10 months ago #55069

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FOCUSPOS is an official FITS header entry, see here . And I do think it should be in the header of all image frames, IMO it's a hardware setting just like GAIN, EXPTIME etc.....
3 years 10 months ago #55152

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This may be exactly what you implied...
Given the values in the link you provided ( fits parameters )perhaps writing all 3 values in the the fits file (if they are available) would extend the posibilities of integration with other code.
FOCUSPOS – Focuser position in steps, if focuser is connected.
FOCUSSSZ – Focuser step size in microns, if available.
FOCUSTEM – Focuser temperature readout in degrees C, if available.
3 years 10 months ago #55157

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This is a very good idea to integrate the focuser parameters into the FITS header
FOCUSPOS – Focuser position in steps, if focuser is connected.
FOCUSSSZ – Focuser step size in microns, if available.
FOCUSTEM – Focuser temperature readout in degrees C, if available.

However in the last KStars version (3.4.2) the FOCUSPOS line doesn't report the current focuser position and stays = 0

Regards,
3 years 10 months ago #55191

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Hi,

do you know if this feature was finally added to Ekos? I bought the ZWP EAF and I have doubts about how to get the focuser position for each set of subframes to reproduce in flats frames (my idea is to refocus on each filter change).

Thanks and regards.
1 year 7 months ago #85829

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Yes, or INDI actually, just configure the correct focuser as snoop target of your camera and you get:

FOCUSPOS= 1861 / Focus position in steps
FOCUSTEM= -6.950E+00 / Focuser temperature in degrees C
The following user(s) said Thank You: Juan Daniel
1 year 7 months ago #85910

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