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Cygwin support?
08-02-2006, 18:22
Post: #1
Cygwin support?
Hi,

Congrats on what appears to be an amazing piece of software.  Before I try to (re)invent a wheel that cannot be invented <smile>, has anyone successfully built SWarp from source under Cygwin on Windows XP?  If so, are there any tips, tricks, or gotchas I should know about?

Thanks,
Jim S.
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08-02-2006, 19:20
Post: #2
RE: Cygwin support?
No "trick" is needed to compile SWarp under Cygwin. Just untar the archive, ./configure and make. If you have multiple cores/processors use ./configure --enable-threads to build the multithreaded version. btw Version 2.16 will be released in the next few days.
Emmanuel.

PS: thanks for the fancy username, I almost erased your account and banned your IP (dummy registrations with this kind of username are generally done prior to try hacking the forum) Smile
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08-02-2006, 21:57
Post: #3
RE: Cygwin support?
Thanks much Emmanuel.  It built without error or warning, so I think it's good to go.

I've read through the PDF documentation and my head is spinning a bit.  Would you mind helping me get started?  I'm trying to convert a synthetic star image I created in IRIS, which is in gnomoic equatorial mode (north = up), to a cylindrical galactic projection.

The synthetic star image was generated with IRIS' "Data base >> Display a Sky Map ..." function, and saved as FITS.  But, unfortunately, IRIS doesn't save much in terms of header information, as an inspection in EMACS (hexl-find-file) reveals.  Is there a way for me to tell SWarp the center coordinates, projection, image scale, etc., of the INPUT image, and then tell it the desired projection of the output image?  If so, how do I do that?

To summarize, I have:
Input: proj=TAN, center=17:59:20.5, -22:31:29, 6.4u pixels, fl=14mm
Output: proj=CYP (or CEA), center=ibid., etc.

Thanks much for your help!

JS
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08-03-2006, 01:21 (This post was last modified: 08-03-2006 01:21 by Henry Joy McCracken.)
Post: #4
RE: Cygwin support?
Hey JS,

Just try running swarp on your image! It will report all the information you are looking for on each input image (pixel scale, image centre...)

the output projection is determined by what is in your swarp.conf. Try swarp -dd to see what the defaults are. Alternatively, it can be specifed by a .head file.

cheers
henry
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08-03-2006, 04:56
Post: #5
RE: Cygwin support?
Hi Henry,

As I hinted in my previous message, IRIS isn't saving that info in my input image.  Here's what SWarp sayeth:

Code:
-------------- File tempwithradec.fit:
    "no ident"  unweighted  no ext. header  3474x2314  16 bits (integers)
    Center: 1.74e+03,1.16e+03   3.47e+03x2.31e+03  Scale: 1x1 /pixel
    Gain: 0 e-/ADU   Flux scaling (astrom/photom): 1 X / 1 X
So, the question remains:  how can I tell SWarp what's in the input file?

Thanks,
JS
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08-04-2006, 10:37
Post: #6
RE: Cygwin support?
Well, looking at that output it seems to me that the WCS in your header isn't correct -isn't even approximately correct. If you load up the image into ds9/skycat/gaia and they try to overplot a reference catalogue (USNOB) are the reference sources on the sources on your image?

If you don't have a correct WCS in your input image, I don't think there is much you can do. You should use SCAMP to get a good WCS!

cheers
henry
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08-04-2006, 17:37
Post: #7
RE: Cygwin support?
Actually SCAMP also needs a WCS-compliant FITS header (even if they are not yet accurate)! The WCS keywords in a FITS header look like
Code:
EQUINOX =            2000.0000 / Mean equinox                                  
RADECSYS= 'ICRS    '           / Astrometric system                            
CTYPE1  = 'RA---TAN'           / WCS projection type for this axis            
CTYPE2  = 'DEC--TAN'           / WCS projection type for this axis            
CRVAL1  =      2.036561437E+02 / World coordinate on this axis                
CRVAL2  =      3.789626358E+01 / World coordinate on this axis                
CRPIX1  =     -7.544414053E+03 / Reference pixel on this axis                  
CRPIX2  =      9.802815674E+03 / Reference pixel on this axis                  
CD1_1   =      5.116453221E-05 / Linear projection matrix                      
CD1_2   =      9.107641904E-07 / Linear projection matrix                      
CD2_1   =      1.352728793E-07 / Linear projection matrix                      
CD2_2   =     -5.129602767E-05 / Linear projection matrix

For more details please see this link and especially this paper.
Emmanuel.
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