In-orbit calibration status of the Insight-HXMT

TL;DR

The paper reports on the calibration status of China's Insight-HXMT X-ray satellite, detailing in-orbit calibration methods, accuracy, and adjustments for precise timing and spectral measurements.

Contribution

It provides the first comprehensive report on in-orbit calibration procedures and results for the Insight-HXMT satellite, including effective area adjustments and timing accuracy.

Findings

Calibration using radioactive sources and celestial objects

Achieved ~100 microsecond timing accuracy

Modified effective area with empirical adjustments

Abstract

As China's first X-ray astronomical satellite, Insight-HXMT (Hard X-ray Modulation Telescope) successfully launched on Jun 15, 2017. It performs timing and spectral studies of bright sources to determine their physical parameters. HXMT carries three main payloads onboard: the High Energy X-ray telescope (HE, 20-250 keV, NaI(Tl)/CsI(Na)), the Medium Energy X-ray Telescope (ME, 5-30 keV, Si-Pin) and the Low Energy X-ray telescope (LE, 1-15 keV, SCD). In orbit, we have used the radioactive sources, activated lines, the fluorescence line, and Cas A to calibrate the gain and energy resolution of the payloads. The Crab pulsar was adopted as the primary effective area calibrator and an empirical function was found to modify the simulated effective areas. The absolute timing accuracy of HXMT is about 100us from the TOA of Crab Pulsar.