GCN Circular 21809

J.W. Broderick (ASTRON), A. Rowlinson (UvA, ASTRON), P.G. Jonker (SRON, RU), R.P. Fender (Oxford), R.A.M.J. Wijers (UvA), B.W. Stappers (Manchester), S. ter Veen (ASTRON), S. Nissanke (RU), A. Shulevski (ASTRON) report on behalf of the LOFAR Transients Key Science Project

From 2017 August 30 - September 4, we observed a large fraction of the localisation error range of the Advanced LIGO/Virgo trigger G299232 (LVC, GCN 21693
Not found
 
 
) with the ILT (International Low-Frequency Array [LOFAR] Telescope). The observations were obtained with the high-band antennas (HBA) at a centre frequency of 145 MHz (bandwidth 15.8 MHz). We used 6 simultaneous beams on the sky, where each beam has a field of view of approximately 12 deg^2 (beam FWHM 3.9 deg). The observations cover roughly 300 deg^2 in total at optimum sensitivity. Each field was observed for 225 min using a number of separate 25-min snapshots.     

The beam centres are given below (RA and Dec in degrees); the Bayestar-HLV localisation was used as a basis for calculating the coordinates of the beams. Two beams in separate pointings were centred on the IceCube neutrino candidate at RA = 28.2 deg, Dec = 44.8 deg (Bartos et al., GCN 21694
Not found
 
 
; Bartos et al., GCN 21698
Not found
 
 
). Furthermore, one beam was centred on the optical transient discovered by Swift/UVOT at RA = 25.035625 deg, Dec = 34.567667 deg (Emery et al., GCN 21733
Not found
 
 
).  

Analysis is ongoing. We thank the ASTRON Radio Observatory for promptly scheduling the observations.


Pointing 1
(integration time 225 min over the period 2017-08-30 23:00 UTC - 2017-08-31 06:21 UTC)

1) 34.039151    46.299866
2) 35.248501    48.949799
3) 28.200000    44.800000
4) 31.322127    48.348415
5) 36.756176    44.251317
6) 37.965526    46.901250

Pointing 2
(integration time 225 min over the period 2017-08-30 23:26 UTC - 2017-08-31 06:47 UTC)

1) 35.780064    51.725205
2) 36.750925    54.437875
3) 31.502071    50.889684
4) 32.472933    53.602354
5) 39.087195    49.848056
6) 40.058057    52.560726

Pointing 3
(integration time 225 min over the period 2017-08-31 23:00 UTC - 2017-09-01 06:21 UTC)

1) 29.306644    35.778068
2) 30.478008    38.389034
3) 25.035625    34.567667
4) 27.105198    37.906547
5) 31.508089    33.649589
6) 32.679454    36.260555

Pointing 4
(integration time 225 min over the period 2017-08-31 23:26 UTC - 2017-09-01 06:47 UTC)

1) 31.825000    41.000000
2) 33.084178    43.610966
3) 28.199341    40.517513
4) 28.200000    44.800000
5) 34.191481    38.871521
6) 35.450659    41.482487

Pointing 5
(integration time 225 min over the period 2017-09-03 01:00-08:21 UTC)

1) 41.738945    68.095823
2) 43.350996    70.808493
3) 34.635623    67.260303
4) 36.247674    69.972972
5) 47.230217    66.218674
6) 48.842268    68.931344

Pointing 6
(integration time 225 min over the period 2017-09-03 01:26-08:47 UTC)

1) 44.937500    79.572222
2) 44.267884    76.796335
3) 31.320689    78.289239
4) 31.990306    81.065126
5) 57.884694    78.079318
6) 58.554311    80.855205

Pointing 7
(integration time 225 min over the period 2017-09-04 00:00-07:21 UTC)

1) 37.337896    57.197845
2) 38.228521    59.934164
3) 32.518303    56.247531
4) 33.408928    58.983851
5) 41.266865    55.411839
6) 42.157490    58.148159

Pointing 8
(integration time 225 min over the period 2017-09-04 00:26-07:47 UTC)

1) 39.119146    62.670484
2) 40.170071    65.406804
3) 33.432096    61.720170
4) 34.483021    64.456490
5) 43.755272    60.884478
6) 44.806196    63.620798