GMRT High Resolution Southern Sky survey

(Bhaswati Bhattacharyya, Jayanta Roy, Jayaram N. Chengalur, Sanjay Kudale, Ben Stappers (University of Manchester, UK), Mike Keith (University of Manchester, UK), Mateusz Malenta (University of Manchester), Sally Cooper (University of Manchester, UK))

GHRSS - GMRT High Resolution Southern Sky survey of pulsars and transients - is an ongoing off galactic plane survey with the GMRT. The sensitivity of the GMRT combined with the sophisticated and flexible software backend (GSB) makes it the premier instrument for searching for pulsars and extra-galactic radio bursts (FRBs) in the southern sky. The simultaneous time domain and imaging capability of this survey provides an unique opportunity of discovery and simultaneous localisation of pulsars and FRBs. GHRSS is an off the galactic plane (|b|>5) survey scanning a portion of sky having declination -40 to -54 at 322 MHz, i.e. declination complementary to other ongoing low frequency surveys with GBT and LOFAR. This portion of sky is not surveyed at frequencies less than 1.4 GHz for last two decade. This survey uses the high resolution survey modes in the GMRT software backend. The survey sensitivity is 0.5 mJy, which is comparable to the GBNCC surveys conducted with  GBT. With the bandwidth of 32 MHz, and sampling rate of 30.72 micro seconds GHRSS generates 76 GB per pointing. Data processing is done in IBM cluster at NCRA and Hydrus supercomputer at JBCA, Manchester. Phase-1 of the survey was funded by Marie Curie grant (PIIF-GA-2013-626533) of European Union of B. Bhattacharyya. A paper describing initial discoveries and the survey parameters can be found on https://arxiv.org/abs/1509.07177. Till now in Phase-1 of the survey covering ∼ 1800 deg^2 of sky (∼62% of the total target sky), we have discovered 13 pulsars including a millisecond pulsar, two mildly recycled pulsars and a pulsar for which we also detect gamma-ray pulsation with Fermi LAT. We have developed a coherently-dedispersed gating correlator (coherently-dedispersed gating correlator - https://arxiv.org/abs/1302.1246) for rapid astrometry of newly discovered pulsars from this survey.
Aided by the upgraded GMRT with increased sensitivity, we are starting Phase-2 part of the GHRSS survey with 200 MHz bandwidth. Calculated theoretical sensitivity for 10 mins pointing duration for the GHRSS Phase-2 at 400 MHz is 0.25 mJy. This is important as we start to probe the lower range of the pulsar luminosity distribution. The FRB fluence also improves to 1 Jy-ms in Phase-2 compared to 3 Jy-ms in Phase-1.  Identification of FRBs with host galaxies through simultaneous localisation using the GMRT interferometer can provide vital inputs in understanding the nature of the FRB phenomenon.
We have 6 discoveries from Phase-2, including one MSP and one RRAT. This is the first RRAT discovered with the GMRT. The MSP is the first MSP discovered with the upgraded GMRT. Discoveries from Phase-2 are marked by  "P2".
Following is the list of pulsars discovered with the GHRSS survey

Pulsar             Period        DM
                      (ms)         (pc/cc)
----------------------------------------
J0418-42         757.11       26.1 
J0514-44	      320.27       15.38 
J0703-50	      666.00       98.7 
J0919-42	      812.62       57.8
J0941-43(P2)   447.7        105.5 
J1023-43(P2)   454.35      62.5
J1239-48	      653.89       107.6
J1243-47(P2)   5.31          78.6
J1255-46	       52.03        42.9 
J1428-42(P2)   234.70       66.0 
J1456-48	       533.81      133.0 
J1516-43	       36.02        70.25 
J1559-44	       1169.89    122.0 
J1708-52	       449.62      102.7 
J1726-52	       631.84      119.7 
J1845-40(P2)    324.18      68.4 
J1947-43	       180.94      29.9 
J2141-52	       5.04          19.6 

 
RRAT               Period        DM
                       (ms)         (pc/cc)
----------------------------------------
J1850-48(P2)	327          23

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