combining with scombine
rohit wrote on Aug 12, 2008
I have a peculiar problem when combining spectra with scombine. There are 4 spectra(call it orders) whose x-axis has pixels which range from 0-1000 for most spectra while the y-axis is normalised flux. I would like to combine them such that I have a spectra of all these orders well separated out. That is just adding each spectrum at the end of the previous spectrum. With 4 spectra, I should expect the x-axis to range from 0 to 4000. I tried "sum" under grouping option but that did not work.
please let me know. Thanks!
please let me know. Thanks!
Francisco Valdes wrote on Aug 12, 2008
Scombine is designed to work in wavelength space; which really means whatever the world coordinates for the first axis are set to. For uncalibrated data this would be pixels.
Anyway, if all you want to do is "tile" the images end-to-end then I suggest you use imcombine with the offsets parameter. In the help you will find that one of the forms of the offsets parameter is a string describing a grid. In you case it might be something like "grid 5 1000 1 1". If they are of different sizes then the more general offsets file could be used whose contents are something like
Note you didn't say if these were 1D or 2D files. My examples assume 2D images which are tiled end-to-end along the first dimension.
Yours,
Frank Valdes
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Anyway, if all you want to do is "tile" the images end-to-end then I suggest you use imcombine with the offsets parameter. In the help you will find that one of the forms of the offsets parameter is a string describing a grid. In you case it might be something like "grid 5 1000 1 1". If they are of different sizes then the more general offsets file could be used whose contents are something like
0 0
1000 0
1900 0
Note you didn't say if these were 1D or 2D files. My examples assume 2D images which are tiled end-to-end along the first dimension.
Yours,
Frank Valdes
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Last post on Aug 12, 2008