How to simply get all RA and Dec for detected sources, and position info (rotational angle, central RA Dec, etc.) from the header

[Jerry Zhang]

Hello experts in astrometry.net,

After the solve-field I get plenty of the detected star in the .axy file with only X and Y pixel values in the image. Now I would like to transform them into their RA and Dec, but I need the position info like the orientation, scale, reference point position and pixels.

I can find reference point pixels and position in the headers of xxx.new fits file, and CD matrix but I would like to directly get the central RA Dec and field rotation angle because my images are fixed FoV. 

These info are shown in the dialogue window:

Field center: (RA,Dec) = (60.821513, 35.265565) deg.

Field center: (RA H:M:S, Dec D:M:S) = (04:03:17.163, +35:15:56.035).

Field size: 7.28873 x 7.28477 arcminutes

Field rotation angle: up is -98.8361 degrees E of N

Field parity: neg

but where are they hiding in the final files? Or is there any way to simply get all the RA Dec for detected sources in .axy file?

Thanks!

Jerry

[Dustin Lang]

Hi,

After you run solve-field, you can use the wcs-xy2rd program to convert from X,Y to RA,Dec:

    wcs-xy2rd -w image.wcs -i image.axy -o image.radec

To get additional information about a WCS solution, you can use:

    wcsinfo image.wcs

which will print out a bunch of stuff including ra_center, dec_center, orientation, etc.

Alternatively, if you set --crpix-center, then in the image.wcs file, the CRPIX1,CRPIX2 values will be the x,y pixel center of the image, and CRVAL1,CRVAL2 will be the central RA,Dec.

cheers,

dustin

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[Jerry Zhang]

It works quite nice!