Adding Orders

To simplify adding orders, we defined two useful S-Lang functions. Using those functions, the procedure becomes fairly trivial:

    _auto_declare = 1;
    () = evalfile ("add_orders.sl");

        % Here are our data files

    pha2_file = "acisf01318N003_pha2.fits.gz";
    m_arf = "acisf01318_000N001MEG_-1_garf.fits.gz";
    p_arf = "acisf01318_000N001MEG_1_garf.fits.gz";

        % Load counts from MEG +1 and -1 orders

    () = load_data (pha2_file, [9,10]);

        % Load matching ARFs

    () = load_arf (m_arf);
    () = load_arf (p_arf);

        % Sum counts in first order and add the ARFs
        % and assign the summed ARF to the summed
        % counts spectrum:

    d = add_orders (1, 2);
    a = add_arfs (1, 2);
    assign_arf (a, d);

        % Divide the counts by the ARF and
        % plot the flux-corrected spectrum

    flux_corr (d);

        % Now plot the flux-corrected spectrum

    id = plot_open ("ex_add_orders.ps/cps");
    plot_data_flux (d);
    plot_close (id);

For an alternative approach to combining datasets, see the description of the combine_datasets function in the ISIS manual.