The S-Lang CFITSIO Module Page

The CFITSIO library consists of a set of functions for reading and writing FITS files. The S-Lang CFITSIO module wraps many of the functions of the CFITSIO library and permits one to easily manipulate FITS files from the S-Lang interpreter.

The module consists of a high-level interface and a low-level one. The high-level interface makes use of the low-level functions to perform common tasks. For example, consider the job of binning the X and Y columns from a binary table into an image and saving the result to a FITS file with the proper WCS:

    infile = "evt2.fits[EVENTS]"; outfile = "img.fits";
    (y,x) = fits_read_col (infile, "Y", "X");
    wcs = fitswcs_get_column_wcs (infile, ["Y","X"]);
    xgrid = [0:8192:8]; ygrid = [0:8192:8];
    img = hist2d (y,x,ygrid,xgrid);
    fits_write_image_hdu (outfile, NULL, img);
    wcs = fitswcs_rebin_wcs (wcs, ygrid, xgrid);
    fitswcs_write_img_wcs (outfile, wcs);

Here, the histogram module's hist2d function was used to bin the image. As the example also indicates, the cfitsio module includes routines to manipulate FITS World Coordinate Systems (WCS).