WCS: What does VPhot need to consider an image plate solved?

Affiliation
Svensk Amator Astronomisk Forening, variabelsektionen (Sweden) (SAAF)
Thu, 04/15/2021 - 06:47

Hi!

I am producing my images via Ekos/Indi, that provides WCS information in the fits header when taking and image. Recently, those images are no longer recognized by VPhot as containing WCS information. As I understand it, nothing has changed in the Ekos process, so I wonder where something has changed. I'd like to not have to perform plate solving as an extra step, if possible. 

This below is the fits header of an image taken yesterday, where the WCS information is not recognized by VPhot (it is flagged as red for WCS). I really do not understand what WCS information is needed here, so grateful for any help to understand this. WHat is lacking here?

Magnus

 

SIMPLE  = T                                 / file does conform to FITS standard
BITPIX  = 16                                     / number of bits per data pixel
NAXIS   = 2                                                / number of data axes
NAXIS1  = 1677                                           / length of data axis 1
NAXIS2  = 1264                                           / length of data axis 2
EXTEND  = T                                / FITS dataset may contain extensions
COMMENT FITS (Flexible Image Transport System) format is defined in 'Astronomy
COMMENT and Astrophysics', volume 376, page 359; bibcode: 2001A&A...376..359H 
BZERO   = 32768                    / offset data range to that of unsigned short
BSCALE  = 1                                             / default scaling factor
ROWORDER= 'TOP-DOWN'                                                 / Row Order
INSTRUME= 'Atik 383L'                                                 / CCD Name
TELESCOP= 'Losmandy Gemini'                                     / Telescope name
OBSERVER= 'Unknown '                                             / Observer name
OBJECT  = 'YZ_Cnc  '                                               / Object name
EXPTIME = 2.000000E+01                                 / Total Exposure Time (s)
CCD-TEMP= -2.50E+01                                  / CCD Temperature (Celsius)
PIXSIZE1= 5.400000E+00                                  / Pixel Size 1 (microns)
PIXSIZE2= 5.400000E+00                                  / Pixel Size 2 (microns)
XBINNING= 2                                            / Binning factor in width
YBINNING= 2                                           / Binning factor in height
XPIXSZ  = 1.080000E+01                          / X binned pixel size in microns
YPIXSZ  = 1.080000E+01                          / Y binned pixel size in microns
FRAME   = 'Light   '                                                / Frame Type
IMAGETYP= 'Light Frame'                                             / Frame Type
FILTER  = 'V       '                                                    / Filter
FOCALLEN= 1.76E+03                                           / Focal Length (mm)
APTDIA  = 2.79E+02                                     / Telescope diameter (mm)
SCALE   = 1.268093E+00                                       / arcsecs per pixel
SITELAT = 5.554810E+01                 / Latitude of the imaging site in degrees
SITELONG= 1.336470E+01                / Longitude of the imaging site in degrees
AIRMASS = 1.184866E+00                                                 / Airmass
OBJCTRA = ' 8 10 55.81'                               / Object J2000 RA in Hours
OBJCTDEC= '28 10 39.01'                            / Object J2000 DEC in Degrees
RA      = 1.227325E+02                              / Object J2000 RA in Degrees
DEC     = 2.817750E+01                             / Object J2000 DEC in Degrees
EQUINOX = 2000                                                         / Equinox
CRVAL1  = 1.2273252910E+02                                              / CRVAL1
CRVAL2  = 2.8177502132E+01                                              / CRVAL1
RADECSYS= 'FK5     '                                                  / RADECSYS
CTYPE1  = 'RA---TAN'                                                    / CTYPE1
CTYPE2  = 'DEC--TAN'                                                    / CTYPE2
CRPIX1  = 8.3850000000E+02                                              / CRPIX1
CRPIX2  = 6.3200000000E+02                                              / CRPIX2
SECPIX1 = 1.2680933633E+00                                             / SECPIX1
SECPIX2 = 1.2680933633E+00                                             / SECPIX2
CDELT1  = 3.5224815648E-04                                              / CDELT1
CDELT2  = 3.5224815648E-04                                              / CDELT2
CROTA1  = 2.6840160000E+02                                              / CROTA1
CROTA2  = 2.6840160000E+02                                              / CROTA2
DATE-OBS= '2021-04-14T19:22:45.762'              / UTC start date of observation
COMMENT Generated by INDI                                                     
END                                                                           

 

Affiliation
American Association of Variable Star Observers (AAVSO)
WCS

Maybe:

'EQUINOX'   '2000.'   'Coordinates referred to ICRS / J2000.0'

Kind regards - Raymond

 

Affiliation
American Association of Variable Star Observers (AAVSO)
Sorry, while reading again…

Sorry, while reading again through your list, I found Equinox. So that's not the problem...

Affiliation
American Association of Variable Star Observers (AAVSO)
WCS

Comparing with the header of my images, I found that following properties are (maybe) missing in your header:

'CD1_1'   'value'   'Scale matrix (1,1)

'CD1_2'   'value'   'Scale matrix (1,2)

'CD2_1'   'value'   'Scale matrix (2,1)

'CD2_2'   'value'   'Scale matrix (2,2)

But I'm not sure if these parameters are responsible for your problem.

Raymond

Affiliation
American Association of Variable Star Observers (AAVSO)
VPhot criteria for deciding image is plate solved

Vphot is looking for the FITS header entry  CD1_1 to decide if the image is solved.

George