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Spectrophotometry with IRAF’s sbands

After a long time I finally managed to understand how to use IRAF’s sbands, along with a standard star and a filter.

1. If you want to use a spectrum from the standard star library of IRAF, you have to convert it from a .dat file to an image file .fits – Spectra files located in …/iraf/iraf/noao/lib/onedstds/ – by using the rspectext.
2. Having created an image file* (of the 1D spectrum), sbands uses this image and a bandpass file to provide the results (fluxes, or magnitudes). The contents of the bandpass file is the bands for which we want to measure flux/mag: name of the band, central wavelength, width, filter transmission file (if available).

*[2014/06/25 update]
Caution: the spectrophotometric files contain 2 columns, the wavelength and the magnitude, which means that they are reversed when plotted – so they have to be transformed into fluxes (in wavelength units) to be used properly.

[originated from: IRAF.net/ spectrophotometry with sbands or something else at ]