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Error in displayed center coordinates
07-21-2014, 20:52
Post: #1
Error in displayed center coordinates
Hi. I am swarping images generated in SIN projection onto a new image with all-sky MOL projection. When I do that the output image looks OK, but I get errors in the displayed center coordinates if the input image has a negative CRVAL1:

-------------- File 1082728336_W_bm1.0_I.2d.fits:
"no ident" WEIGHTED no ext. header 3072x3072 32 bits (floats)
Center: 00:00:00.00 +01:40:53.8 2.3e+03'x2.3e+03' Scale: 45 ''/pixel
Gain: 0 e-/ADU Flux scaling (astrom/photom): 1 X / 1 X
Background: -0.002166669 RMS: 0.1916401 Weight scale: 1

The software that generated the image put
CRVAL1=-179.0582

If I change the header to add 360 deg. to CRVAL1 it all works OK:

-------------- File 1082728336_W_bm1.0_I.2d.fits:
"no ident" WEIGHTED no ext. header 3072x3072 32 bits (floats)
Center: 12:03:47.53 +01:40:53.8 2.3e+03'x2.3e+03' Scale: 45 ''/pixel
Gain: 0 e-/ADU Flux scaling (astrom/photom): 1 X / 1 X
Background: -0.003276675 RMS: 0.1257356 Weight scale: 1

Again, in both cases the output images were fine but it took some investigation to figure out why the displayed coordinates were 0 and that there was no actual problem.

Thanks,

David
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