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[b:f8fc3e06bf]From: [/b:f8fc3e06bf]Médéric Boquien <mederic.boquien@laposte.net ([email]mederic.boquien@laposte.net[/email])>
[b:f8fc3e06bf]Date: [/b:f8fc3e06bf]July 7, 2005 8:15:12 AM MST
[b:f8fc3e06bf]To: [/b:f8fc3e06bf]iraf@noao.edu ([email]iraf@noao.edu[/email])
[b:f8fc3e06bf]Subject: [/b:f8fc3e06bf][b:f8fc3e06bf]polyphot / coordinate problems using wcsin=world[/b:f8fc3e06bf]
Doctor,
I'm having a problem with polyphot when using wcsin=world. The polygon 
coordinates i get from the output of polyphot are systematically shifted by a 
few pixels compared to the coordinates i get from rd2xy.
For instance, if in the input file i have RA = 338.9848512, Dec =  33.9610800, 
polyphot would ouput: 525.25   264.70 (in a sample image), when in fact the 
right coordinate would be 537.  268.75 (determined directly on the image, 
confirmed with xy2rd)
Using xy2rd and rd2xy i always get 
RA = 338.9848512, Dec =  33.9610800 <=>  X =   537.00, Y =   268.75
Here is my parameter file of polyphot:
image   =     SQ_fd_redim.fits  The input image(s)
(polygon=             SQ22.ver) The input polygons file(s) (default: 
image.ver.?)
(coords =                     ) The input coordinates file(s) (default: 
image.coo.?)
(output =              default) The output photometry file(s) (default: 
image.mag.?)
(datapar=                     ) Data dependent parameters
(centerp=                     ) Centering parameters
(fitskyp=                     ) Sky fitting parameters
(polypar=                     ) Photometry parameters
(interac=                   no) Interactive mode ?
(icomman=                     ) Image cursor: [x y wcs] key [cmd]
(gcomman=                     ) Graphics cursor: [x y wcs] key [cmd]
(wcsin  =                world) The input coordinate system 
(logical,tv,physical,world)
(wcsout =            )_.wcsout) The output coordinate system 
(logical,tv,physical)
(cache  =                   no) Cache the input image pixels in memory ?
(verify =            )_.verify) Verify critical parameters in non-interactive 
mode ?
(update =            )_.update) Update critical parameters in non-interactive 
mode ?
(verbose=           )_.verbose) Print messages in non-interactive mode ?
(graphic=          )_.graphics) Graphics device
(display=           )_.display) Display device
(mode   =                   ql)
wcsout defaults to logical.
If i use logical coordinates (using rd2xy) in the input file, the output is 
correct, the points of the polygon are not shifted.
I've tried on different images from different source and the problem is the 
same so i don't think it comes from the images.
Let me know if you need additional informations/a sample file.
What should i do to get correct results? Is one of my parameters wrong?
Thank you very much, regards,
Médéric Boquien

[b:f8fc3e06bf]From: [/b:f8fc3e06bf]Frank Valdes <valdes@noao.edu ([email]valdes@noao.edu[/email])>
[b:f8fc3e06bf]Date: [/b:f8fc3e06bf]July 13, 2005 12:33:14 PM MST
[b:f8fc3e06bf]To: [/b:f8fc3e06bf]mederic.boquien@laposte.net ([email]mederic.boquien@laposte.net[/email])
[b:f8fc3e06bf]Subject: [/b:f8fc3e06bf][b:f8fc3e06bf]Re: polyphot / coordinate problems using wcsin=world[/b:f8fc3e06bf]
Hello Médéric,
I don't know the source of your problem immediately.  You don't have to send me the image but just the header listing (the output of "imhead SQ_fd_redim.fits l+").  Please also send the polygon file.  It does not appear I would need any other file from you parameter information.
Yours,
Frank Valdes