The GMRT High Resolution Southern Sky Survey for Pulsars and Transients. V. Localization of Two Millisecond Pulsars

The timing follow-up of newly discovered millisecond pulsars (MSPs) is hindered by the larger positional uncertainty (a few tens of arcminutes) associated with the discovery. In this paper, we present the localization of two MSPs, discovered by the GMRT High Resolution Southern Sky survey, up to arcsecond accuracy using a 33 MHz offline coherently dedispersed gated correlator. This gated correlator is an upgraded version of the earlier 16 MHz design. This new development with a factor of 2 enhancement in the observing bandwidth offers better sensitivity in the image domain, leading to more precise localization. Aided by the precise position, we followed up these two MSPs with sensitive phased-array (PA) beams of upgraded GMRT from 300 to 1460 MHz. More sensitive observations in the PA mode for these two MSPs yield precise (∼sub-μs) time-of-arrivals, with dispersion measure uncertainties in the range of 10−4–10−5 pc cm−3. We also report the profile evolution of the two MSPs over 300–1460 MHz. Finally, we discuss the suitability of these MSPs for the pulsar timing array experiments aimed to detect low-frequency gravitational waves.