{
  "bibcode": "2018GCN.22651....1B",
  "body": "J.W. Broderick (ASTRON), K. Gourdji (UvA), A. Rowlinson (UvA, ASTRON),\nP.G. Jonker (SRON, RU), A.J. Stewart (SIfA), R.P. Fender (Oxford),\nR.A.M.J. Wijers (UvA), B.W. Stappers (Manchester), S. ter Veen\n(ASTRON), S. Nissanke (RU), A. Shulevski (UvA) report on behalf of the\nLOFAR Transients Key Science Project\n\nFrom 2018 April 7-15, we observed a large fraction of the localisation\nregion of the Advanced LIGO/Virgo trigger G299232 (LVC, GCN 21693)\nwith the ILT (International Low-Frequency Array [LOFAR]\nTelescope). The observations were obtained with the high-band antennas\n(HBA) at a centre frequency of 145 MHz (bandwidth 15.8 MHz). We used 6\nsimultaneous beams on the sky, where each beam has a field of view of\napproximately 12 deg^2 (beam FWHM 3.9 deg). The observations cover\nroughly 300 deg^2 in total at optimum sensitivity. Each field was\nobserved for 245 min using a number of separate 25-min snapshots, as\nwell as a single 20-min snapshot.\n\nThe beam centres are given below (RA and Dec in degrees); the\nBayestar-HLV localisation was used as a basis for calculating the\ncoordinates of the beams. The pointing setup is identical to the\nprevious sets of LOFAR follow-up observations described in Broderick\net al., GCN 21809, GCN 21962 and GCN 22172. Two beams in separate\npointings were centred on the IceCube neutrino candidate at RA = 28.2\ndeg, Dec = 44.8 deg (Bartos et al., GCN 21694; Bartos et al., GCN\n21698). Furthermore, one beam was centred on the optical transient\ndiscovered by Swift/UVOT at RA = 25.035625 deg, Dec = 34.567667 deg\n(Emery et al., GCN 21733).\n\nAnalysis is ongoing. We thank the ASTRON Radio Observatory for\nscheduling the observations.\n\nPointing 1\n(integration time 245 min over the period 2018-04-07 08:48 UTC -\n2018-04-07 16:56 UTC)\n\n1) 34.039151    46.299866\n2) 35.248501    48.949799\n3) 28.200000    44.800000\n4) 31.322127    48.348415\n5) 36.756176    44.251317\n6) 37.965526    46.901250\n\nPointing 2\n(integration time 245 min over the period 2018-04-07 08:27 UTC -\n2018-04-07 16:35 UTC)\n\n1) 35.780064    51.725205\n2) 36.750925    54.437875\n3) 31.502071    50.889684\n4) 32.472933    53.602354\n5) 39.087195    49.848056\n6) 40.058057    52.560726\n\nPointing 3\n(integration time 245 min over the period 2018-04-08 08:25 UTC -\n2018-04-08 16:33 UTC)\n\n1) 29.306644    35.778068\n2) 30.478008    38.389034\n3) 25.035625    34.567667\n4) 27.105198    37.906547\n5) 31.508089    33.649589\n6) 32.679454    36.260555\n\nPointing 4\n(integration time 245 min over the period 2018-04-08 08:04 UTC -\n2018-04-08 16:12 UTC)\n\n1) 31.825000    41.000000\n2) 33.084178    43.610966\n3) 28.199341    40.517513\n4) 28.200000    44.800000\n5) 34.191481    38.871521\n6) 35.450659    41.482487\n\nPointing 5\n(integration time 245 min over the period 2018-04-14 08:51 UTC -\n2018-04-14 16:59 UTC)\n\n1) 41.738945    68.095823\n2) 43.350996    70.808493\n3) 34.635623    67.260303\n4) 36.247674    69.972972\n5) 47.230217    66.218674\n6) 48.842268    68.931344\n\nPointing 6\n(integration time 245 min over the period 2018-04-14 08:30 UTC -\n2018-04-14 16:38 UTC)\n\n1) 44.937500    79.572222\n2) 44.267884    76.796335\n3) 31.320689    78.289239\n4) 31.990306    81.065126\n5) 57.884694    78.079318\n6) 58.554311    80.855205\n\nPointing 7\n(integration time 245 min over the period 2018-04-15 08:30 UTC -\n2018-04-15 16:38 UTC)\n\n1) 37.337896    57.197845\n2) 38.228521    59.934164\n3) 32.518303    56.247531\n4) 33.408928    58.983851\n5) 41.266865    55.411839\n6) 42.157490    58.148159\n\nPointing 8\n(integration time 245 min over the period 2018-04-15 08:09 UTC -\n2018-04-15 16:17 UTC)\n\n1) 39.119146    62.670484\n2) 40.170071    65.406804\n3) 33.432096    61.720170\n4) 34.483021    64.456490\n5) 43.755272    60.884478\n6) 44.806196    63.620798",
  "circularId": 22651,
  "createdOn": 1524053766000,
  "email": "b.a.rowlinson@uva.nl",
  "subject": "LIGO/Virgo G299232: LOFAR follow-up",
  "submitter": "Antonia Rowlinson at U van Amsterdam  <b.a.rowlinson@uva.nl>",
  "eventId": "LIGO/Virgo G299232"
}