Fermi-LAT data reprocessed with updated calibration constants

TL;DR

This paper details the reprocessing of four years of Fermi-LAT data with updated calibration constants, leading to reduced systematic uncertainties and improved data analysis accuracy.

Contribution

It reports on the significant update of calibration constants and reprocessing of the Fermi-LAT data, enhancing data quality and analysis reliability.

Findings

Reduced systematic uncertainties in data analysis

Improved low- and high-level analysis results

Enhanced data calibration accuracy

Abstract

Four years into the mission, the understanding of the performance of the Fermi Large Area Telescope (LAT) and data analysis have increased enormously since launch. Thanks to a careful analysis of flight data, we were able to trace back some of the most significant sources of systematic uncertainties to using non-optimal calibration constants for some of the detectors. In this paper we report on a major effort within the LAT Collaboration to update these constants, to use them to reprocess the first four years of raw data, and to investigate the improvements observed for low- and high-level analysis. The Pass 7 reprocessed data, also known as P7REP data, are still being validated against the original Pass~7 (P7) data by the LAT Collaboration and should be made public, along with the corresponding instrument response functions, in the spring of 2013.