A new determination of the INTEGRAL/IBIS point source location accuracy

TL;DR

This paper presents an improved determination of the INTEGRAL/IBIS telescope's point source location accuracy, based on extensive analysis of in-flight data, which enhances the precision of source localization for follow-up observations.

Contribution

The study provides a significantly improved PSLA measurement for INTEGRAL/IBIS using a large dataset and updated analysis software, refining previous estimates.

Findings

PSLA has improved since early mission data.

The accuracy enhancement reduces search areas by over 50%.

Results apply to both fully and partially coded fields of view.

Abstract

AIMS: To determine the Point Source Location Accuracy (PSLA) for the INTEGRAL/IBIS telescope based on analysis of archival in-flight data. METHODS: Over 40000 individual pointings (science windows) of INTEGRAL/IBIS data were analysed using the latest Off-line Science Analysis software, version 7.0. Reconstructed source positions were then compared against the most accurate positions available, determined from focusing X-ray telescopes. Since the PSLA is a strong function of source detection significance, the offsets from true position were histogrammed against significance, so that the 90% confidence limits could be determined. This has been done for both sources in the fully coded field of view (FCFOV) and partially coded field of view (PCFOV). RESULTS: The PSLA is found to have improved significantly since values derived from early mission data and software for both FCFOV and PCFOV. CONCLUSIONS: This result has implications for observers executing follow-up programs on IBIS sources since the sky area to be searched is reduced by >50% in some cases.