identify doesn’t find the right spectrum
Polly wrote on Jan 25, 2010
Hi,
I'm trying to do some wavelenght calibrations on a set of spectra in one file. (It's an Argus spectrum so I have 310 spectra where 13 are sky fibers). Identify is working fine on one-dimensional images but as soon as I want to identify or reidentiy a certain column of a two-dimensional image like "identify image[21,*]" it is NOT taking the right column (even if I try it with the section parameter). May be I missunderstand something but when I plot it, it says that it plots image[21,*] but it's not (because this is supposed to be a sky line as it appears with splot for example). And it also writes "file[1,*]" in the idfile instaed of the 20th column.
What am I doing wrong? Why can't I tell the programm to identify this sky line. I don't know what to do anymore I don't want to copy every single fiber in one-dimensional images.
Thank you.
Nora
I'm trying to do some wavelenght calibrations on a set of spectra in one file. (It's an Argus spectrum so I have 310 spectra where 13 are sky fibers). Identify is working fine on one-dimensional images but as soon as I want to identify or reidentiy a certain column of a two-dimensional image like "identify image[21,*]" it is NOT taking the right column (even if I try it with the section parameter). May be I missunderstand something but when I plot it, it says that it plots image[21,*] but it's not (because this is supposed to be a sky line as it appears with splot for example). And it also writes "file[1,*]" in the idfile instaed of the 20th column.
What am I doing wrong? Why can't I tell the programm to identify this sky line. I don't know what to do anymore I don't want to copy every single fiber in one-dimensional images.
Thank you.
Nora
Francisco Valdes wrote on Jan 25, 2010
Two things occur to me. One is that when you extracted the Argus data the identifications got mixed up. This happens if one doesn't look carefully and the numbering either starts at 1 though it should have been fiber 2 or the skipping of
bad or unused fibers is not correct.
Related to this may be that you are confusing aperture numbers and row numbers. The extractions and operations applied to logical apertures. This is so one may retain some desirable number system. But the row numbers are obviously the order in which the apertures are stored in the file. There is a mapping between the logical aperture and the row number in the various tasks that operate on this format. So you may want aperture 21 which is not necessarily stored in row 21. You can use slist or imhead to look at information about this mapping.
If you are still confused you can post or send me a header listing and a specific simple example. This is probably your identify example. While it may be possible to use an image section, many tasks designed around the "multispec" format have facilities to select spectra by logical aperture. So what you really might need to do is use something like "identify [file]" and then the commands within identify to go to aperture 21. Note that when you use an image section the image is automatically turned into a 1D image before the application even sees it though it may be smart enough to figure out where the 1D image it sees was located in the 2D format.
Yours,
Frank Valdes
bad or unused fibers is not correct.
Related to this may be that you are confusing aperture numbers and row numbers. The extractions and operations applied to logical apertures. This is so one may retain some desirable number system. But the row numbers are obviously the order in which the apertures are stored in the file. There is a mapping between the logical aperture and the row number in the various tasks that operate on this format. So you may want aperture 21 which is not necessarily stored in row 21. You can use slist or imhead to look at information about this mapping.
If you are still confused you can post or send me a header listing and a specific simple example. This is probably your identify example. While it may be possible to use an image section, many tasks designed around the "multispec" format have facilities to select spectra by logical aperture. So what you really might need to do is use something like "identify [file]" and then the commands within identify to go to aperture 21. Note that when you use an image section the image is automatically turned into a 1D image before the application even sees it though it may be smart enough to figure out where the 1D image it sees was located in the 2D format.
Yours,
Frank Valdes
Polly wrote on Jan 25, 2010
Hi Frank,
Yes I mixed up aperture number and row number :-) Thank you very much for your help.
Nora
Yes I mixed up aperture number and row number :-) Thank you very much for your help.
Nora
Last post on Jan 25, 2010