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This study is intended to address concerns raised by Stefan in his energy dispersion studies and results for the region containing IC443 (and W44).
The input simulations
The model includes Galactic diffuse, isotropic diffuse, and IC443:
- The "standard" Galactic diffuse model, gal_2yearp7v6_v0.fits, only extends down to 50 MeV, and in simulations, this is the minimum value of MCENERGY of the generated events. However, in the likelihood model mapcube representation, the model is power-law extrapolated (at each pixel) beyond the energy bounds of the map. So there will be a mis-match between the model use for simulation and that used for the likelihood analysis. To prevent this inconsistency, I've created version of the model that power-law extrapolates down to 3 MeV (I've also rebinned in sky coordinates to 0.5x0.5 deg pixels so that the simulation proceeds more quickly.) On slac afs, the file is /afs/slac/g/glast/groups/scienceTools/bugs/Likelihood/energy_dispersion/Simulations/galdif_extended.fits.
- Similarly, I've used a version of iso_p7v6source.txt (prepared by Josh) that extrapolates down to 10 MeV. For emin=20 MeV in gtselect, this should be fine. The file is /afs/slac/g/glast/groups/scienceTools/bugs/Likelihood/energy_dispersion/Simulations/iso_p7v6source_extrapolated.txt
- IC443: Here I use the standard MapSource template, /afs/slac/g/glast/groups/catalog/2FGL/gll_psc_v05_templates/IC443.fits, and a smoothly broken power-law with parameters:
- Index1 = -0.5
- Scale = 100
- Index2 = -1.9
- BreakValue = 250
- Beta = 0.1
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