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Home > Data Analysis > UVOT > Spectra

Creating spectral files

For UVOT spectral files, the canned response matrices are available in the CALDB. They can either be copied to the working directory, or used directly in situ. These are named swu<filter>_dateversion.rsp, where dateversion will be something like 20041120v104. Run uvot2pha, adding the extension number to the input filename.

>uvot2pha 
Input (img or evt) filename []: sw00374210000uuu_sk.img.gz+1 
Source region file name []: Usource.reg 
Background region file name []: Uback.reg 
Output source PHA filename []: Usource.pha 
Output background PHA filename []: Uback.pha 
Response file name []: CALDB

Note that the EBOUNDS extension of the response matrices may need the numbers swapping over (to be lowest energy first); by default, E_MIN will appear larger than E_MAX. This switch is necessary for use in ISIS, and also if you wish to use setplot area in XSPEC (though not for "normal" XSPEC plotting). To make this change, copy the relevant RMF from the CALDB, open the file using fv, and switch round the E_MIN and E_MAX values in the EBOUNDS extension. Then use this file as the input when prompted for the Response file name, rather than the default version from the CALDB.

Also, because the bandpasses of some of the filters overlap in energy/wavelength space, so, too, will the spectral points.