Loving ISIS - Confessions of a Former XSPEC User

Summary

OK, that was a lot of territory to cover in a few pages. But the goal was to cover 98% of the ISIS commands that I need more than once in a blue moon. Plus I wanted to show a worked example of ISIS applied to something that's not Chandra gratings data. ISIS can be used on lots of different kinds of data sets.

Just to demonstrate that it's not nearly as difficult as it might have seemed, here is a condensed version of the analysis script. This version skips some of the slower stuff (e.g., reflection models), and just does a doubly broken power law plus gaussian model fit to the radio/X-ray data. It does use my .isisrc scripts. Including calculation of a complete set of error bars, and calculation of the Gamma_2 vs. Gamma_3 contours (961 grid points), the script runs in about 5 minutes on my 2.8 GHz Intel Core 2 Duo Powerbook. The data for this script can be found here.

Again, use of the scripts on these pages presumes you have downloaded my .isisrc files and placed them in your home directory before launching ISIS.

   variable radio_data = read_radio("radio.data",50);
   variable radio_id = load_radio(radio_data);

   variable pca_id = load_data("pca.pha");
   set_sys_err_frac(pca_id,Double_Type[129]+0.005);
   group(pca_id;min_sn=5.5,bounds=3.,unit="kev");
   notice_values(pca_id,3.,22.;unit="kev");

   variable hexte_id = load_data("hxt.pha");
   group(hexte_id;min_sn=20.,bounds=18.,unit="kev");
   notice_values(hexte_id,18.,200.;unit="kev");

   model("constant(Isis_Active_Dataset)*phabs(1)*highecut(1)*(bkn2pow(1)+gaussian(1))");

   newpar(2,0.6,-1);
   newpar(3,50,0,10,200);
   newpar(4,150,0,1,1000);
   newpar(5,230,0,0,1.e4);
   newpar(6,0.829,0,0.7,1.0);
   newpar(7,5.e-4,0,1.e-6,10);
   newpar(8,1.7,0,1.4,2);
   newpar(9,10.,0,8,12);
   newpar(10,1.5,0,1,2);
   newpar(11,2.e-3,0,0,0.1);
   newpar(12,6.4,-1);
   newpar(13,0.3,0,0,1.5);
   newpar(14,1,-1);
   newpar(15,0.98,0,0.5,1.5);

   () = renorm_counts;
   () = fit;

   variable id=open_print("short_fit.ps/vcps");
   keynote_size; nice_width;
   xlog; ylog;

   plot_unfold({1,2,3};res=3,power=3,dsym={18,4,6},rsym={18,4,6},
                       dcol={8,17,4},rcol={8,17,4}               );
   close_print(id,"gv");

   (,) = conf_loop(,1,1.e-3;save,prefix="bkn2pow_gaussian.");

   variable px = conf_grid(8,1.67,1.70,31);
   variable py = conf_grid(10,1.43,1.52,31);
   variable cntr = conf_map(px,py);

   () = save_conf(cntr,"bkn2pow_gauss_g2_vs_g3.contour");


   variable id = open_print("bkn2pow_gauss_g2_vs_g3_contour.ps/vcps");
   keynote_size; nice_width;
   xlin; ylin; xrange; yrange;
   xlabel("\\fr Photon Index, \\gG\\d2");
   ylabel("\\fr Photon Index, \\gG\\d3");

   plot_conf(cntr);

   close_print(id,"gv");

Next up: Download Startup File