Alfacal is a utility for accessing the ALFA spectral parameters and calibration determined by Desh by providing an interface to his fortran subroutine. See Desh's memo for a description of how the paraemeters were derived.
To run Alfacal at AO, type
~rminchin/progs/alfacal 〈centrefreq〉 〈bandwidth〉 〈option〉 〈zenith angle〉
The output gives the value and the error for each beam and polarisation (note that the error is the error on the points averaged across the bandwidth and does not include any error in the zenith angle correction). It is formatted as follows:
Gain over 80. MHz centred on 1380. MHz at ZA = 5. degrees. ZA correction factors: 1. 1. Beam 0: Pol 1 Pol 2 Value: 11.1839018 11.1677742 Error: 0.0305875093 0.0309901554 Beam 1: Pol 1 Pol 2 Value: 8.70151711 8.48216057 Error: 0.0294616111 0.0266611632 Beam 2: Pol 1 Pol 2 Value: 8.86137962 8.92475986 Error: 0.0264299996 0.0278139934 Beam 3: Pol 1 Pol 2 Value: 8.23973179 8.23015118 Error: 0.030120587 0.0266778171 Beam 4: Pol 1 Pol 2 Value: 8.51489735 8.40820503 Error: 0.0296856202 0.0287898406 Beam 5: Pol 1 Pol 2 Value: 9.25692749 8.89543724 Error: 0.0294356942 0.0314402729 Beam 6: Pol 1 Pol 2 Value: 8.97087383 8.80161095 Error: 0.0295731761 0.0271398723
Note that the ZA correction factors are given with respect to a zenith angle of 5 degrees, which is the zenith angle to which the calibrations have been normalised.
Alfacal should run fine at Arecibo, if you want to run it elsewhere you need to make a local installation. To install Alfacal, you will need to download and unpack the datafiles in ALFA_POLY_FITS.tar.gz. You then need to download the fortran sourcecode for Alfacal, alfacal.f and change the section:
c Alter this bit if the ALFA_POLY_FITS files have been installed in c a different directory. character*39 path path='/share/rminchin/alfacal/ALFA_POLY_FITS/'
so that ‘path’ points to the directory in which you have installed the ALFA_POLY_FITS files and has the exact length required (set character*N path where N is the length of the pathname).
Now simply compile the program using, e.g., f77 alfacal.f -o alfacal and you should be able to run it using the above instructions.