Add WCS coordinates after plate solve


#1

It doesn’t seem that plate solving using Astrometry.net adds the WCS coordinates to the image.

I want to use eXcalibrator (http://bf-astro.com/eXcalibrator/excalibrator.htm) to calibrate the RGB exposure times and this requires WCS coordinates be added to the fits header. Particularly:

Option A Option B
BITPIX BITPIX
BZERO, BSCALE
(16-bit only)
BZERO, BSCALE
(16-bit only)
NAXIS1,NAXIS2 NAXIS1, NAXIS2
CRPIX1, CRPIX2 CRPIX1, CRPIX2
RPIX1, CRPIX2 CRPIX1, CRPIX2
CD1_1, CD1_2 CDELT1, CDELT2
CD2_1, CD2_2 CROTA1, CROTA2
CRVAL1, CRVAL2 CRVAL1, CRVAL2
CTYPE1, CTYPE2 CTYPE1, CTYPE2

Is it something I am missing? Or is it something that could be added to SGP?

Fred Klein


#2

No, you’re correct that it doesn’t. It probably could be added since the information is present.

Chris


#3

Moving to feature requests


#4

Anyone have a good work around? Can I use my local astrometry server to add WCS tags to a local file?

Pinpoint is darn near worthless.


#5

There is no easy way to get the WCS info from the local astrometry.net solver to the image without having SGP do it. Technically the info is available when the solve completes, but we really need SGP to add it to the image headers.

As a workaround, if you have PixInsight, you can use its image solver (Script => Image Analysis => ImageSolver) which will add the WCS headers.

Andy


#6

Andy,

Yea, I ended up doing that. But I had to type in the ‘rough’ coordinates for each one because ImageSolver is not blind and when you’re doing mosaics they’re not close enough to type in ‘North American Nebula’.

I think most my wasted time was trying to do it automatically. The worst part was Pinpoint 6 wouldn’t do it… couldn’t find any stars in the image it said.


#7

I found a workaround to get WCS data into images. Use the on-line astrometry.net at http://nova.astrometry.net/upload Upload the image and when finished click on “Go to results page” Then download the “new-image.fits”

BTW, I used this data with the eXcalibrator program and it gave me rations of Red-1.000, Green-1.180, Blue-1.793 for my STT-8300M with the RGB filters from SBIG.

Fred Klein


#8

Thanks Fred. That’s a good idea!


#9

Archiving. A 2.4.X version will see a complete switch of ALL coordinates used within the application to JNow.


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