imcombine offsets recognized but not implimented

mzagursk wrote on Aug 27, 2010

Hey All,

I am running imcombine to stack/offset many small images. It seems that no matter what offset i choose (both physical and wcs), it produces a file with the correct header information (naxis1 and naxis2) but when I open it, it is simply the last file in the combine list. Also, it shows the correct offsets when I run the command, however it never seems to combine them. Any ideas?

Cheers

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mzagursk wrote on Aug 27, 2010

To give some more information in hopes of help here's my epar imcombine:

input   = extracted8310.fits,extracted8311.fits  List of images to combine
output  =                 testoutput  List of output images
(headers=                     ) List of header files (optional)
(bpmasks=                     ) List of bad pixel masks (optional)
(rejmask=                     ) List of rejection masks (optional)
(nrejmas=                     ) List of number rejected masks (optional)
(expmask=                     ) List of exposure masks (optional)
(sigmas =                     ) List of sigma images (optional)
(imcmb  =                   $I) Keyword for IMCMB keywords
(logfile=               STDOUT) Log file

(combine=              median) Type of combine operation
(reject =                 none) Type of rejection
(project=                   no) Project highest dimension of input images?
(outtype=                 real) Output image pixel datatype
(outlimi=                     ) Output limits (x1 x2 y1 y2 ...)
(offsets=                  wcs) Input image offsets
(masktyp=                 none) Mask type
(maskval=                    0) Mask value
(blank  =                   0.) Value if there are no pixels

(scale  =                 none) Image scaling
(zero   =                 none) Image zero point offset
(weight =                 none) Image weights
(statsec=                     ) Image section for computing statistics
(expname=                     ) Image header exposure time keyword

(lthresh=                INDEF) Lower threshold
(hthresh=                INDEF) Upper threshold
(nlow   =                    1) minmax: Number of low pixels to reject
(nhigh  =                    1) minmax: Number of high pixels to reject
(nkeep  =                    1) Minimum to keep (pos) or maximum to reject (neg)(mclip  =                  yes) Use median in sigma clipping algorithms?
(lsigma =                   3.) Lower sigma clipping factor
(hsigma =                   3.) Upper sigma clipping factor
(rdnoise=                   0.) ccdclip: CCD readout noise (electrons)
(gain   =                   1.) ccdclip: CCD gain (electrons/DN)
(snoise =                   0.) ccdclip: Sensitivity noise (fraction)
(sigscal=                  0.1) Tolerance for sigma clipping scaling corrections(pclip  =                 -0.5) pclip: Percentile clipping parameter
(grow   =                   0.) Radius (pixels) for neighbor rejection
(mode   =                   ql)

and here is the output from IRAF:

Aug 30 15:06: IMCOMBINE
  combine = average, scale = none, zero = none, weight = none
  blank = 0.
                Images    Offsets
     extracted8310.fits  608    0
     extracted8311.fits    0    0

  Output image = help, ncombine = 2

All looks well, and when I do an imhead on the new file, i get:

help[1232,608][real]: Object

as expected. However, when I display the image (or just open it in ds9), all I get is an image of one of the two frames.

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Last post on Aug 27, 2010