Extracting PSF Images

We have created a standalone code that serves to both read them and as a template library for inclusion in other codes. The code is available as: readAtlasImages-v5_4_11.tar.gz.

Compiling

1. % make clean

2. % make

If you are on a big-endian machine, remove -DSDSS_LITTLE_ENDIAN from CFLAGS in the Makefile.

Using

% read_PSF -h
Usage: read_PSF [options] input-file hdu output-file
Your options are:
       -?      This message
       -h      This message
       -i      Print an ID string and exit
       -v      Turn up verbosity (repeat flag for more chatter) 

To reconstruct the z PSF (i.e. the 5th HDU) at the position (row, col) = (500, 600) from run 1336, column 2, field 51 you'd say:

%  read_PSF psField-001336-2-0051.fit 5 500.0 600.0 foo.fit 

The desired PSF would appear as an unsigned short FITS file in foo.fit; the background level is set to the standard `soft bias' of 1000. If you want a floating image, change a line in the read_PSF.c; look for

        /* create a float region */

Developer Comments

The standalone programs read_atlas_image (reads fpAtlas files) and read_mask (reads fpM files) are similar. All three are built by the same 'make' command.

I don't expect that many users will actually want to use the read_PSF executable (although it is perfectly functional). The main use of the product will probably be to link into custom built executables that need to process atlas image data. I believe that the code should be easily reused for this purpose.