TITLE: GCN CIRCULAR NUMBER: 18690 SUBJECT: LIGO/Virgo G184098: LOFAR follow-up DATE: 15/12/14 16:54:15 GMT FROM: Antonia Rowlinson at U van Amsterdam A. Rowlinson (UvA, ASTRON), J. Broderick (ASTRON), P.G. Jonker (SRON/RU), R.P. Fender (Oxford), R.A.M.J. Wijers (UvA), B.W. Stappers (Manchester) report on behalf of the LOFAR Transients Key Science project On Dec 14, 2015, starting at 02.00 (UTC), we observed a large fraction of the localization error range at declinations larger than 0 degrees of the Advanced LIGO trigger G184098 with the ILT (International Low-Frequency Array [LOFAR] Telescope). This is the final set of LOFAR observations of these fields, our other two runs were completed on Sept 21, 2015 (GCN 18364) and Oct 16, 2015 (GCN 18424). The observations were obtained with the High-Band Antennas (HBA) at a centre frequency of 145 MHz (bandwidth 11.9 MHz). In this configuration, the ILT can provide 8 simultaneous beams on the sky, where each beam has a field of view of approximately 12 deg^2 (beam FWHM 3.9 degrees). The beam centres are given below: 1) 132.500000 5.166667 08:50:00.00 +05:10:00.0 2) 135.287125 5.166667 09:01:08.91 +05:10:00.0 3) 129.712875 5.166667 08:38:51.09 +05:10:00.0 4) 131.106458 7.572944 08:44:25.55 +07:34:22.6 5) 131.106458 2.760389 08:44:25.55 +02:45:37.4 6) 133.893542 7.572944 08:55:34.45 +07:34:22.6 7) 133.893542 2.760389 08:55:34.45 +02:45:37.4 8) 128.319333 2.760389 08:33:16.64 +02:45:37.4 The observations cover roughly 50 square degrees in total. Each field was observed for a total of 3.7 hr with 10s time resolution after pre-processing. Analysis is ongoing.