# Large Area X-ray Proportional Counter (LAXPC) Instrument on AstroSat and Some Preliminary Results from its performance in the orbit

## TL;DR

The LAXPC instrument on AstroSat provides high time resolution X-ray observations in the 3-80 keV range, with successful in-orbit performance demonstrated through initial timing and spectral results from X-ray sources.

## Contribution

This paper details the design, laboratory testing, and in-orbit calibration of the LAXPC instrument, highlighting its large effective area and high detection efficiency for X-ray astronomy.

## Key findings

- LAXPC achieved effective area over 6000 cm2 at 15 keV.
- Successful in-orbit calibration and initial observations of X-ray sources.
- Performance matches pre-launch expectations for timing and spectral capabilities.

## Abstract

Large Area X-ray Propositional Counter (LAXPC) instrument on AstroSat is aimed at providing high time resolution X-ray observations in 3 to 80 keV energy band with moderate energy resolution. To achieve large collecting area, a cluster of three co-aligned identical LAXPC detectors, is used to realize an effective area in access of about 6000 cm2 at 15 keV. The large detection volume of the LAXPC detectors, filled with xenon gas at about 2 atmosphere pressure, results in detection efficiency greater than 50%, above 30 keV. In this article, we present salient features of the LAXPC detectors, their testing and characterization in the laboratory prior to launch and calibration in the orbit. Some preliminary results on timing and spectral characteristics of a few X-ray binaries and other type of sources, are briefly discussed to demonstrate that the LAXPC instrument is performing as planned in the orbit.