Stumbled upon the various different licenses I though to write down some conclusions (if I really got into any…). A nice comparison table of free software licenses is given in the Wikipedia where it is easily to see which licenses allow: (i) the link with other licenses and (ii) releasing …
While running a data reduction of IR observations with IRAF, the ccdproc printed this error: ERROR (502, “floating point invalid operation”) which means that some values of the image used (the flat image in this case) are not suitable for the performing mathematical actions (like division with 0s). Moreover the …
Flatcombine and Darkcombine (based on imcombine both) in IRAF just combine the images given as input to create a master flat / dark image without performing any normalization. This is done when using ccdproc with the parameters flatcor and darkcor set to yes.
Although hedit of IRAF is supposed to handle the keywords of a fits file (add, remove) its behaviour can be misleading sometimes. An error like this: ERROR (1121, “FXF: EOF encountered while reading FITS file (something.fits)”) means that after altering the keywords in the header the EOF of the header …
From “A User’s Guide to CCD Reductions with IRAF” by Philip Massey (iraf’s photometry docs) we read at page 19 §3.8 that there are two useful options to set the reject parameter: > reject parameter = crreject when we know the gain and read noise of our camera > reject …
Without login.cl iraf/pyraf does not work properly. Some commands may execute (like zerocombine, ie the binaries) but when the command will need to retrieve some information (like wavelength calibration/plotting, even shell commands like ls ) it will not respond (see error examples below). IRAF: Select a directory (like user’s home) …
AAOmega (at Anglo-Australian Observatory) observations can be reduced with 2dfdrv4 tool pretty much very easilly. But the reduction ‘s final output is a combined fits image which includes all spectra from the 400 fibers. So, the user has to extra by himself/herself the spectra individually and this has been frustrating …
Installing IRAF can always be a huge problem. Many pages exist explaining all the necessary steps to install it but I have never tried to follow these (like Rubab’s tutorials for 32 and 64 bit Ubuntu/Debian, Michael Hutchinson’s tutorial for 64 bit Ubuntu – these tutorials explain how to install …
What do you get if you combine IRAF and Python ? Of course something that starts with Py and ends with RAF, PyRAF, which combines IRAF’s tasks with the Python’s command (allowing to create more sophisticated scripts than the cl ones). But in order to implement these abilities in a …
In order to get a specific field from the header of a file you can use the command: cl> imhead inage.fit l+ | grep name_of_field In case you want to do it for many files you just use the wildcard: cl> imhead inage*.fit l+ | grep name_of_field Not very sophisticated …