solve again an image already solved

[tano...@gmail.com]

Hi Dustin, Hi everybody

I would like to solve an image that astrometry (local version) already solved but with another star catalog.

For example suppose I'd like to solve an image with 5200 index, and this image is already solved with 4100 index.

From the first solving procedure, astrometry returns these files: .axy, .corr, .out, .rdls, .solved, .wcs, .xyls

Can I use one of these files to solve again the image?

What I know is that the .xyls file returns the x y coordinates of the stars present in the field of view (is it right?), and that I can use this information to solve an image.

If I can use one of the files mentioned above file, what should be the solve-field line command format?

Thanks for the help.

GZ

[Dustin Lang]

Hi,

You can do

solve-field --verify X.wcs  [ + your usual arguments ]

which will check the original solve results against the new star catalog.

You can either pass in the original image file again, and it will re-detect stars.  Or you can pass the X.xyls file as the input (rather than X.fits or X.jpg)

cheers,

dustin

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[Gaetano Zarcone]

Thanks Dustin,

I have another question 

If I use the xyls file as input, does astrometry solve image faster than if I use the original file?

Cheers

Gaetano

[Dustin Lang]

Well, it doesn't have to re-detect stars in the image, so that part will be faster

[Gaetano Zarcone]

Ok

Thanks again Dustin

Cheers

Gaetano 

[tano...@gmail.com]

Hi Dustin

I tried what you suggested, using --verify X.wcs wiht the following solve-field command line:

'solve-field --verify /home/tanozar/Research/Images/GEO/Prova/PNG/Out/Raw.wcs --dir /home/tanozar/Research/Images/GEO/Prova/PNG/Out_new --no-remove-lines --uniformize 0 --temp-dir /tmp/astroref --config /home/tanozar/Research/RGB_Catalog/astrometry_rgb.cfg --no-plots -s MAG_AUTO -a -X X_IMAGE -Y Y_IMAGE --new-fits none --use-source-extractor --source-extractor-config /home/tanozar/anaconda3/envs/latest_env/share/sextractor/default_2nd.sex --match none --tag-all --crpix-center --overwrite --downsample 1 --tweak-order 3 --scale-units app --scale-low 9.9 --scale-high 10.5 --width 3670 --height 5496 /home/tanozar/Research/Images/GEO/Prova/PNG/Out/Raw-indx.xyls > /home/tanozar/Research/Images/GEO/Prova/PNG/Out_new/Raw.out 2>&1'

and astrometry doesn't work. So I read the .out file which reports this:

"Reading input file 1 of 1: "/home/tanozar/Research/Images/GEO/Prova/PNG/Out/Raw-indx.xyls"...
qfits: error: NAXIS = 0 in file /home/tanozar/Research/Images/GEO/Prova/PNG/Out/Raw-indx.xyls ext 0
an-fitstopnm.c:225:main: Failed to load pixels.
Command failed: /home/tanozar/anaconda3/envs/latest_env/bin/an-fitstopnm -i /home/tanozar/Research/Images/GEO/Prova/PNG/Out/Raw-indx.xyls > /tmp/astroref/tmpt2qp8v_y.pnm
augment-xylist.c:591:backtick Failed to run command: /home/tanozar/anaconda3/envs/latest_env/bin/image2pnm --infile /home/tanozar/Research/Images/GEO/Prova/PNG/Out/Raw-indx.xyls --uncompressed-outfile /tmp/astroref/tmp.uncompressed.PM9YXG --outfile /tmp/astroref/tmp.ppm.kmtcWi --ppm --mydir /home/tanozar/anaconda3/envs/latest_env/bin/solve-field
 ioutils.c:568:run_command_get_outputs Command failed: return value 255"

Opening the .xyls file with fv I found what you see in the attached image (0 and 1 in red refers to the 0 and 1 index of the xyls file)

It seems that no image is loaded (NAXIS = 0) but in the header related to index 1 NAXIS = 2.

What's wrong?

Cheers

Gaetano

[Dustin Lang]

Hi,

The -indx.xyls file contains "index stars" (stars from the reference catalog) projected into your X,Y pixel space.  You want to use the "axy" file instead.

And based on this error message, you *may* need to add

--extension 1

to tell it to read the first FITS extension (rather than the primary).

cheers,

dustin

To view this discussion on the web visit https://groups.google.com/d/msgid/astrometry/996be294-9675-4997-9783-e30ad7490cc8n%40googlegroups.com.

[Gaetano Zarcone]

Ok Dustin

I'll try it. 

Cheers

Gaetano