Large Area X-ray Proportional Counter

Department of Astronomy & Astrophysics, TIFR

Launched on September 28, 2015

India's first dedicated multi-wavelength astronomy satellite, AstroSat got launched at 10:00 AM on 28th September by PSLV C-30 from Satish Dhawan Space Centre (SDSC), SHAR. It has five science payloads which will cover from X-ray to UV wavelength. The Large Area X-ray Proportional Counter (LAXPC) is one of the major payloads on AstroSat, which covers 3-80 keV energy range. The three LAXPC units on Astrosat has large effective area and sensitivity. The LAXPC instrument will bring a wealth of data on a variety of astrophysical objects in the 3-80 keV X-ray band, with fine time resolution of 10 microseconds.

LAXPC Detectors during integration

The LAXPC Detectors in clean room during integration on AstroSat.

Latest News

DT-10 Status.

High Voltage of
Switched Off
08:13UT @ 08th March, 2018


First Light of LAXPC on
19th Oct, 2015

Detector Front End Electronics Switched ON
1st Oct, 2015

Electronics Switched ON
30th Sept. 2015

STBG Switched ON
29th Sept. 2015

The LAXPC instrument is designed & developed at TIFR. The principal scientific objectives of LAXPC instrument are as follows:
  • Detailed studies of stellar-mass black holes with masses ~ 3-10 M in our Galaxy and the neighbouring galaxies and massive black holes (~106 to 109 M) in AGNs will be realized with the LAXPC instrument. This will be achieved by measuring variations in the luminosity of sources and the time scales of variations.

  • Studies of periodic (pulsations, binary light curves, QPOs etc.) and aperiodic (flaring activity, bursts, flickering and other chaotic variations) variability in X-ray pulsars and other X-ray binaries, coronal X-ray sources, Cataclysmic Variables (CVs), Active Galactic Nuclei (AGNs) and other galaxies etc. by high time resolution (~10µsec) photometry over a wide spectral band covering 3-80 keV with a single instrument. Rapid variability studies e.g. sub-second variations, high and low frequency QPOs and kHz QPOs in soft and hard x-ray bands, probe astrophysical processes closest to the central source.

  • Low to moderate spectral resolution studies of continuum X-ray emission over a broad band of 3-80 keV for X-ray binaries, Supernova remnants (SNRs), CVs, Stellar Coronae, AGNs etc. This will be done using large area and low to moderate energy resolution ( ∆ E / E ~ 10 to 20 %) of LAXPCs.

  • Correlated time variations of intensity in 3-80 keV band with those in the visible, UV and soft X-ray (0.3-8 keV) bands to investigate the origin and mechanism of emission of radiation indifferent wave bands.

  • Discovery of non-thermal components in the X-ray spectra of SNRs and Clusters of Galaxies by accurate spectral measurements in 3-80 keV band combined with simultaneous measurements from SXT in 0.3-8 keV region to estimate their magnetic field strength as well as to understand the acceleration processes and origin of cosmic rays in the case of SNRs.

  • Measuring magnetic fields of neutron stars by detection and studies of cyclotron lines, most of which lie in 15-60 keV regions in the X-ray spectra of x-ray pulsars.

  • Search for X-ray transient sources will be conducted by repeated surveys in the limited regions of the galactic plane with the LAXPC.

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