Instrument Response Functions

Effective Area

The collection area, which is proportional to the gamma-ray efficiency of detection, is computed as a function of the true energy. The events which are considered are the ones passing the threshold of the best cutoff plus the angular cuts.

Energy Dispersion Matrix

The energy dispersion matrix, ratio of the reconstructed energy over the true energy as a function of the true energy, is computed with the events passing the threshold of the best cutoff plus the angular cuts.

The corresponding energy migration matrix can be build from the dispersion matrix.

Point Spread Function

The PSF describes the probability of measuring a gamma ray of a given true energy and true position at a reconstructed position.

Background rate

The background rate is calculated as the number of background-like events per second, reconstructed energy and solid angle. The current version is computed in radially symmetric bins in the Field Of View.

Reference/API

pyirf.irf Package

Functions

`effective_area`(n_selected, n_simulated, area)	Calculate effective area for histograms of selected and total simulated events
`effective_area_per_energy`(selected_events, ...)	Calculate effective area in bins of true energy.
`effective_area_per_energy_and_fov`(...)	Calculate effective area in bins of true energy and field of view offset.
`effective_area_3d_polar`(selected_events, ...)	Calculate effective area in bins of true energy, field of view offset, and field of view position angle.
`effective_area_3d_lonlat`(selected_events, ...)	Calculate effective area in bins of true energy, field of view longitude, and field of view latitude.
`energy_dispersion`(selected_events, ...)	Calculate energy dispersion for the given DL2 event list.
`psf_table`(events, true_energy_bins, ...)	Calculate the table based PSF (radially symmetrical bins around the true source)
`background_2d`(events, reco_energy_bins, ...)	Calculate background rates in radially symmetric bins in the field of view.