The discussion clarifies the distinction between 1D and 2D spectra in spectroscopy. A 2D spectrum is obtained from a CCD after exposure with a spectrograph, representing the object across multiple pixels. To derive a 1D spectrum, users sum the pixel counts from the 2D profile along a row or column, resulting in a vector of total counts versus pixel number. Tools like Ghostview and Ghostscript are necessary for reading PostScript files, while additional complexities arise with Echelle spectrographs and multi-object spectrographs.
PREREQUISITESResearchers in spectroscopy, astrophysics students, and professionals working with CCD imaging and spectral analysis will benefit from this discussion.
AstroRoyale said:2-d spectra are what you have on the CCD after taking an exposure with the spectrograph. The object that you are taking a spectrum of, say a star, typically extends over several pixels wide on the ccd chip. To get a 1-d spectrum, you sum up all the counts in the pixels in the 2-d profile in each row or column depending on how the chip is oriented, and subtract off any unwanted backgrounds at the same time. The end result is a 1-dimensional vector of total counts vs pixel number. For a quick and dirty 1-d spectrum, you can just plot across one of the rows/columns in the spectrum (again depending on the orientation of the ccd).
The gory details can be found in the link below. . .
http://iraf.noao.edu/iraf/ftp/iraf/docs/spect.ps.Z
AstroRoyale said:Why were you not able to open the file, works for me at least. Try this one instead perhaps. . .
http://iraf.net/irafdocs/spect.pdf
To read .ps (postscript) you need a free program called ghostview and ghostscript, they are available for just about all platforms.randa177 said:I think my computer doesn't read the .ps.Z files, do you know how can I fix that?
mgb_phys said:To read .ps (postscript) you need a free program called ghostview and ghostscript, they are available for just about all platforms.
The .Z is a compressed file (rather like .Zip but more common on unix) I think newer versions of ghostview can read them automatically - otherwise something like 7zip will uncompress them.
There are other types of 2d spectra, an Echelle puts multiple orders of the same spectra in different parts of the image, so the same line can appear many times - they are a little more complex to process. There are also multi-object spectrographs that produce spectra of many different objects in the same field at the same time
mgb_phys said:If you installed from a package then it should have been put on one of the application menus, or double clicking on the .ps file should start it.
Otherwise 'gv' from the command line.