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Plate-solving DSLR raw files

CrossoverManiac
Affiliation
American Association of Variable Star Observers (AAVSO)
Thu, 08/29/2019 - 19:53

I have been trying to perform plate solving on some .cr2 files I took with my canon camera and telephoto lens as a dry run.  When I submitted .cr2 file to VPHOT, it said I had to plate solve them. The only way I've been able to plate solve them was to convert them to .FIT and plate solve them at nova.astrometry.net.  Unfortunately, when I did that, I lost the DATE-OPS FIT header and the time the image was taken was changed to the time the image was plate-solved, which makes sense since it's a whole new image.  My question is how to plate-solve my files and submit them to VPHOT without messing up the FIT header?

Tonisee
Affiliation
American Association of Variable Star Observers (AAVSO)
Thu, 08/29/2019 - 21:18
FITS header editing

Hello!

Seems that you may need to edit your FITS files after solving. I'm doing all of those things under Linux using wcs-tools utilities. If you're a Windows user, you could have a look e.g. at:

http://astroshed.com/fits4win/f4w2hdudoc.htm

However, I looked at nova.astrometry.net public images and it seems to me, that it definitely adds keyword DATE - and that's according to FITS standard as well. Also, I uploaded one of my images, and it added previously not present DATE keyword, leaving DATE-OBS intact. Have you confirmed that you don't have two (or even more) versions of date and time in your FITS file headers?

IMHO for VPHOT (and according to FITS standard) you would need either DATE and UT or DATE-OBS (latter preferred). DATE-OBS is usually in format YYYY-MM-DDTHH:MM:SS and it has to be in UTC.

Best wishes,
Tõnis

MZK
Affiliation
American Association of Variable Star Observers (AAVSO)
Thu, 08/29/2019 - 21:46
Raw Images Files

Timothy:

Did you truly try to upload a cr2 file to VPhot? That won't work. You need to split your cr2 image into separate RGB images and save each in FITS format.

Have you read the DSLR User Guide? I would recommend that you ask for a mentor familiar with DSLR observing.

Forgive me if I am missing something obvious?

Ken 

CrossoverManiac
Affiliation
American Association of Variable Star Observers (AAVSO)
Fri, 08/30/2019 - 15:25
Did you truly try to upload a

Did you truly try to upload a cr2 file to VPhot? That won't work. You need to split your cr2 image into separate RGB images and save each in FITS format.

 

I was mistaken.  The image was converted to a .FIT file first.  Sorry for that obvious mistake.

Ed Wiley_WEY
Affiliation
American Association of Variable Star Observers (AAVSO)
Sat, 08/31/2019 - 01:51
FITS header information

Dis you use Upload Wizard or Quick Upload? if you used Quick Upload, did your fits header have all the required information?

  • DATE-OBS TIME-OBS or UT-START
  • EXPTIME or EXPOSURE
  • OBJCTRA or RA (for plate solving)
  • OBJCTDEC or DEC (for plate solving)
  • FILTER: should be B, V, R or I. If so VPhot can automatically use the correct photometry sequence
  • OBJECT: displayed in the image list to recognize images

Ed

 

ps - I don't do DSLR, so I am not familiar with FITS headers in DSLR images.