The IBIS / ISGRI Source Location Accuracy

TL;DR

This paper evaluates the source location accuracy of the INTEGRAL IBIS/ISGRI telescope using ten years of data and improved analysis techniques, providing updated error estimates and future prospects.

Contribution

It introduces new data analysis procedures and fitting methods that improve the accuracy estimation of source localization for the IBIS/ISGRI instrument.

Findings

Typical 90% confidence error at S/N=10 is 1.5 arcmin.

Updated parameters for source location error based on new analysis.

Future plans include refining the PSF fitting and bias correction techniques.

Abstract

We present here results on the source location accuracy of the INTEGRAL IBIS/ISGRI coded mask telescope, based on ten years of INTEGRAL data and on recent developments in the data analysis procedures. Data were selected and processed with the new Off-line Scientific Analysis pipeline (OSA10.0) that benefits from the most accurate background corrections, the most performing coding noise cleaning and sky reconstruction algorithms available. We obtained updated parameters for the evaluation of the point source location error from the source signal to noise ratio. These results are compared to previous estimates and to theoretical expectations. Also thanks to a new fitting procedure the typical error at 90% confidence level for a source at a signal to noise of 10 is now estimated to be 1.5 arcmin. Prospects for future analysis on the Point Spread Function fitting procedure and on the evaluation of residual biases are also presented. The new consolidated parameters describing the source location accuracy that will be derived in the near future using the whole INTEGRAL database, the new fitting technique and the bias correction, will be included in future versions of OSA.