A new determination of the INTEGRAL/IBIS point source location accuracy
Hill, A. B.; Bird, A. J.; Scaringi, S.; McBride, V. A.; Bazzano, A.; Clark, D. J.; Dean, A. J.; Natalucci, L.; Stephen, J. B.
Netherlands, United Kingdom, France, Italy
Abstract
Aims: We determine the point source location accuracy (PSLA) of the INTEGRAL/IBIS telescope based on analysis of archival in-flight data.
Methods: Over 40 000 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 with the most accurate positions available, determined using focusing X-ray telescopes. Since the PSLA is a strong function of source detection significance, histograms of the offsets from true position were compiled to determine the 90% confidence limits 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 measurements were first made for 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 more than 50% in some cases.