| Abstract : | We present the deployment of a 32-MHz gated imaging correlator for the GMRT and the application of the same for localizing newly discovered pulsars with the GMRT.
This gated correlator is an extension of the previous 16-MHz design. The GMRT High-Resolution Southern Sky (GHRSS) survey has discovered 25 pulsars till now. Pulsar discovery is only half of the job, we can determine the rotational and astrometric properties for these newly discovered pulsars only after follow-up studies enabled by the precise localization of the order of a few arcseconds. However, the positional uncertainties achieved, at the time of discovery of a pulsar, lie within tens of arc minute range for the GHRSS survey at 400 MHz. Precise positions can be achieved by pulsar timing follow-up requiring more than a year to minimize the covariance between astrometric and other timing parameters. However, benefited by the interferometric nature, we can localize pulsars in a few arc-sec with gated imaging allowing follow-up studies with sensitive phased array and accelerating convergence towards accurate timing solutions. The Gated imaging technique deployed by us in the GMRT utilizes the periodic property of pulsars to remove all the other continuum sources in the image plane resulting in unambiguous localization of pulsed emission. Such precise localization of the newly discovered pulsars is warranted to minimize the covariance between astrometric and other timing parameters. Moreover, precise localization will allow follow-up studies with the sensitive phased array. In addition to the details of the 32-MHz bandwidth gated correlator, we will also present imaging results for a couple of GMRT pulsars. |
