POLIX, developed by the Raman Research Institute (RRI), Bengaluru is a Thomson X-ray Polarimeter, which aims to measure the degree and angle of polarization of cosmic X-ray sources in the medium X-ray energy range (8-30 keV).

The instrument consists of a collimator, a Beryllium scatterer surrounded by Xenon filled X-ray proportional counters as X-ray detectors, and signal processing electronics. During source observation, the instrument is rotated around the viewing axis which leads to azimuthal distribution of the scattered X-ray photons to provide information on polarisation. Polarised X-rays, incident on the scatterer through the collimator, will produce a variable azimuthal distribution in the count rate as opposed to uniform azimuthal distribution of count rate for unpolarised X-rays and detector background. POLIX has four independent detectors, each with its own front end and processing electronics. Localization of the X-ray photons in the detectors is done by the method of charge division in a set of resistive anode wires connected in series.

XSPECT is a ‘X-ray Spectroscopy and Timing’ payload, onboard XPoSat mission. XSPECT can provide fast timing and good spectroscopic resolution (<200 eV at 6 keV) in soft X-rays (0.8 – 15 keV). Taking advantage of the long duration observations required by POLIX to measure X-ray polarization, XSPECT can provide long-term monitoring of sources to observe spectral state changes in continuum emission, changes in their line flux and profile, simultaneous long term temporal monitoring of soft X-ray emission etc. XSPECT will observe several types of sources viz X-ray pulsars, blackhole binaries, low-magentic field neutron star (NS) in LMXBs, AGNs etc.