TITLE: GCN CIRCULAR NUMBER: 18344 SUBJECT: LIGO/Virgo G184098: DESGW followup program DATE: 15/09/20 02:09:36 GMT FROM: M. Soares-Santos at Fermi Lab M. Soares-Santos (Fermilab), J. Annis (Fermilab), E. Berger (Harvard) D. J. Brout (UPenn), H.-Y. Chen (UChicago), P. Cowperthwaite (Harvard), H. T. Diehl (Fermilab), B. Farr (UChicago), J. Frieman (UChicago), M. Garcia (CIEMAT/Madrid), R. Gruendl (NCSA), D. Hollowood (UCSC), D. Holz (UChicago), R. Kessler (UChicago), A. Kim (LBNL), K. Hefner (Fermilab), E. Neilsen (Fermilab), M. Sako (UPenn), B. Yanny (Fermilab) On behalf of the DESGW team: We report on observations done with the Dark Energy camera (DECam) on the Blanco telescope at CTIO on the night of 2015-09-17 in response to the LVC trigger G184098. Our observations were delayed by 1 night due to the mag 8.1 earthquake near CTIO. DECam has a 3 sq-deg field of view, and typically reaches i,z = 23rd limiting magnitudes for 90 sec exposure times. We covered 5% of the LIGO probability map in 2h of observing time. We covered 80 sq-deg to 23.25 5-sigma point source limiting magnitude in i,z bands. Coordinates are given below. Analysis is underway. ra dec 105.241671 -69.46246 72.711983 -65.40533 99.430667 -69.84 68.298046 -63.8895 95.986417 -68.35239 110.757033 -68.87642 115.898475 -68.09865 109.488283 -70.73343 103.3931 -71.25164 115.164875 -70.00358 120.35765 -69.0844 65.041267 -62.8751 93.434754 -69.99717 65.802783 -60.8461 62.9234 -59.8316 125.044417 -67.99968 129.235458 -66.77258 68.870837 -61.8606 125.215963 -69.94243 72.150367 -62.8751 62.107867 -57.8027 87.38715 -69.92876 83.908596 -71.39367 81.427092 -69.63706 84.793617 -68.22478 82.565254 -66.48404 79.328883 -67.84927 77.530833 -66.03508 [GCN OPS NOTE(19sep15): This Circular was originally published on 22:20 18-Sep-2015 UT.]