Absolute Time Calibration of LAXPC aboard AstroSat

TL;DR

This paper details the precise calibration of AstroSat's LAXPC instrument's timing using Crab Pulsar observations, enabling accurate multi-wavelength timing studies by cross-referencing with Fermi-LAT and ground radio telescopes.

Contribution

It introduces a method for absolute time calibration of AstroSat's LAXPC using pulsar timing and cross-instrument comparison, improving timing accuracy for high-energy astrophysics.

Findings

Determined fixed timing offsets of LAXPC relative to Fermi-LAT and radio telescopes.

Compared LAXPC timing offsets with those of CZTI for consistency.

Enhanced the accuracy of AstroSat's timing calibration for multi-wavelength studies.

Abstract

The AstroSat mission carries several high-energy detectors meant for fast timing studies of cosmic sources. In order to carry out high precision multi-wavelength timing studies, it is essential to calibrate the absolute time stamps of these instruments to the best possible accuracy. We present here the absolute time calibration of the AstroSat LAXPC instrument, utilising the broadband electromagnetic emission from the Crab Pulsar to cross calibrate against Fermi-LAT and ground based radio observatories Giant Metrewave Radio Telescope (GMRT) and the Ooty Radio Telescope (ORT). Using the techniques of pulsar timing, we determine the fixed timing offsets of LAXPC with respect to these different instruments and also compare the offsets with those of another AstroSat instrument, CZTI.