Indian Pulsar Timing Array Experiment (InPTA) is a pulsar timing experiment searching for low frequency nanoHz Gravitational Waves in operation since 2016. InPTA is a Indo-Japanese collaboration which makes use of the unique capabilities of the upgraded Giant Meterwave Radio Telescope (uGMRT) for monitoring a sample of nearby millisecond pulsars for this purpose. InPTA is a member of International Pulsar Timing collaboration (IPTA). The Aitoff map on the right shows all the pulsars observed for the experiment.

High-precision measurements of the pulsar dispersion measure (DM) are possible using telescopes with low-frequency wideband receivers. We present an initial study of the application of the wideband timing technique, which can simultaneously measure the pulsar times of arrival (ToAs) and DMs, for a set of five pulsars observed with the upgraded Giant Metrewave Radio Telescope (uGMRT) as part of the Indian Pulsar Timing Array (InPTA) campaign. We have used the observations with the 300-500 MHz band of the uGMRT for this purpose. We obtain high precision in DM measurements with precisions of the order 10^-6cm^-3pc. The ToAs obtained have sub-μs precision and the root-mean-square of the post-fit ToA residuals are in the sub-μs range. We find that the uncertainties in the DMs and ToAs obtained with this wideband technique, applied to low-frequency data, are consistent with the results obtained with traditional pulsar timing techniques and comparable to high-frequency results from other PTAs. This work opens up an interesting possibility of using low-frequency wideband observations for precision pulsar timing and gravitational wave detection with similar precision as high-frequency observations used conventionally. Read the full article here.

PSR J1713+0747 is one of the most precisely timed pulsars in the international pulsartiming array experiment. This pulsar showed an abrupt profile shape change betweenApril 16, 2021 (MJD 59320) and April 17, 2021 (MJD 59321). In this paper, we report the results from multi-frequency observations of this pulsar carried out withthe upgraded Giant Metrewave Radio Telescope (uGMRT) before and after the event. We demonstrate the profile change seen in Band 5 (1260 MHz - 1460 MHz) andBand 3 (300 MHz - 500 MHz). The timing analysis of this pulsar shows a disturbanceaccompanying this profile change followed by a recovery with a timescale of ~140days. Our data suggest that an achromatic exponential dip model is preferred overmodels with an inverse square or inverse quartic frequency dependence in Band 5. Read the full article here.