The accuracy of Monte Carlo simulations in reproducing the scientific performance of space telescopes ( e.g .
angular resolution ) is mandatory for a correct design of the mission .
A brand-new Monte Carlo simulator of the Astrorivelatore Gamma ad Immagini LEggero ( AGILE ) /Gamma-Ray Imaging Detector ( GRID ) space telescope , AGILESim , is built using the customizable Bologna Geant4 Multi-Mission Simulator ( BoGEMMS ) architecture and the latest Geant4 library to reproduce the instrument performance of the AGILE/GRID instrument .
The Monte Carlo simulation output is digitized in the BoGEMMS postprocessing pipeline , according to the instrument electronic read-out logic , then converted into the onboard data handling format , and finally analyzed by the standard mission on-ground reconstruction pipeline , including the Kalman filter , as a real observation in space .
In this paper we focus on the scientific validation of AGILESim , performed by reproducing ( i ) the conversion efficiency of the tracker planes , ( ii ) the tracker charge readout distribution measured by the on-ground assembly , integration , and verification activity , and ( iii ) the point-spread function of in-flight observations of the Vela pulsar in the 100 MeV – 1 GeV energy range .
We measure an in-flight angular resolution ( FWHM ) for Vela-like point sources of 2.0 ^ { +0.2 } _ { -0.3 } and 0.8 ^ { +0.1 } _ { -0.1 } degrees in the 100 - 300 and 300 – 1000 MeV energy bands , respectively .
The successful cross-comparison of the simulation results with the AGILE on-ground and in-space performance validates the BoGEMMS framework for its application to future gamma-ray trackers ( e.g .
e-ASTROGAM and AMEGO ) .