IRF production
Summary
Description: This use case is related to the SimPipe use case "UC1: Simulate the response of CTA for IRF generation" (ref. CTA-TRE-COM-304000-0003 v1). The derivation of Instrument Response Functions (IRFs) such as the effective area (vs. true and reconstructed energy), the energy dispersion matrix (true vs. reconstructed energy), the gamma-ray Point Spread Function (PSF) and the background model (vs. reconstructed energy and direction) requires the production of Monte Carlo (MC) simulations.
The SimPipe simulates the response of CTA with a given simulation model (determined by the Simulation Scientist, Calibration Scientist etc). The resulting MC simulation is stored in the Bulk Data Archive as SIM-DL0 product, and further processed by the pipelines up to DL2 data (following the same pipeline as for real data with minor specific differences e.g. in the calibration stage). This data is then processed by the CalibPipe to produce the IRFs. An example is the comparison of the true event energies in the simulation and the energy reconstructed by the pipeline giving rise to the energy dispersion matrix.
Alternatives: Muon images for alternative PSF.
Related requirements:
- B-DPPS-1460: The DPPS shall produce IRFs within the required systematic uncertainties for all CTA data products that pass event quality selection.
- B-DPPS-3200: The DPPS shall be able to calculate the instrument response functions necessary for science analysis (including the PSF, Background Model, Acceptance Model and Migration Matrix) for each Good Time Interval.
- B-DPPS-3210: The DPPS shall provide (as meta-data associated with IRFs) the configuration, atmospheric conditions, appropriate energy range and offset radius within which IRFs are valid and the required systematic uncertainties are met.
- B-DPPS-3220: The DPPS shall ensure that an uncertainty on error estimation in the generation of high-level instrumental response function data are always included.
- B-DPPS-3230: The DPPS shall provide a set of associated IRFs with time validity information for each Good Time Interval as part of the DL3 data products.
- B-DPPS-3255: The DPPS shall deliver IRFs associated with each Observation Block that are valid up to at least twice the gamma-ray field of view radius at all energies.
- B-DPPS-37xx: The DPPS shall calculate alternative estimates of the optical PSF of each telescope from muon analysis and use these to monitor and improve the accuracy of the monitored optical PSF.