TITLE: GCN CIRCULAR NUMBER: 20376 SUBJECT: LIGO/Virgo G268556: DESGW/DECam observations DATE: 17/01/05 23:14:01 GMT FROM: M. Soares-Santos at Fermi Lab M. Soares-Santos (Fermilab), J. Annis (Fermilab), E. Berger (Harvard) D. J. Brout (UPenn), R. Butler (Fermilab), H.-Y. Chen (UChicago), P. Cowperthwaite (Harvard), H. T. Diehl (Fermilab), Z. Doctor (UChicago), B. Farr (UChicago), D. Finley (Fermilab), R Foley, W-F Fong (Arizona), J. Frieman (UChicago), M. Garcia-Belido (CIEMAT/Madrid), R. Gruendl (NCSA), K. Herner (Fermilab), D. Holz (UChicago), R. Kessler (UChicago), E. Neilsen (Fermilab), A. Palmese (UCL), M. Sako (UPenn), B. Yanny (Fermilab) On behalf of the DECam GW follow-up team and the DESGW team: We report on observations of LVC trigger G268556 conducted with the Dark Energy camera (DECam) on the Blanco telescope at CTIO as part of NOAO program 2016B-0124 (PI: Berger). The observations commenced on 2017-01-05 01:34:45 UT (15 hours following the GW detection), and consisted of 90-sec exposures in i-band. We observed about 10% of the localization probability map in 4h of observing time, covering 230 sq. deg. to a 5-sigma point source limiting magnitude of i~23 AB mag. Coordinates are given below. Analysis is underway. radec 0.430246 -35.4841 358.640221 -34.45238 4.146646 -37.5131 14.386904 -42.5855 355.722346 -33.4384 2.265329 -36.4986 16.634896 -43.5999 355.386617 -31.41045 6.077717 -38.5275 353.648446 -32.42443 0.096254 -37.5131 357.452083 -32.42443 12.230792 -39.542 12.212492 -41.571 358.27245 -36.48033 18.7554 -42.5855 8.062783 -39.542 1.970025 -38.5275 16.510696 -41.571 10.106204 -40.5565 18.962325 -44.6144 5.874796 -40.5565 10.018408 -42.5855 12.1923 -43.5999 14.3376 -40.5565 3.894796 -39.542 21.375646 -45.6289 21.375646 -45.6289 4.374242 -35.4841 21.0774 -43.5999 10.185421 -38.5275 7.914283 -41.571 2.53245 -34.4696 23.482921 -44.6144 14.441625 -44.6144 25.97865 -45.6289 23.882129 -46.6434 8.196946 -37.5131 6.261133 -36.4986 16.772746 -45.6289 18.568996 -40.5565 16.398796 -39.542 53.652854 -47.6579 25.519996 -43.5999 32.378042 -46.6434 19.192333 -46.6434 55.827133 -46.6434 20.808883 -41.571 27.492404 -42.5855 29.962592 -43.5999 28.003529 -44.6144 58.434467 -47.6579 30.305954 -45.6289 28.572029 -46.6434 36.758192 -48.6723 37.067833 -46.6434 33.226408 -42.5855 39.308158 -47.6579 57.923654 -45.6289 60.517033 -46.6434 48.871258 -47.6579 34.908854 -45.6289 29.744954 -47.6579 23.123908 -42.5855 25.107092 -41.571 51.137342 -46.6434 53.32065 -45.6289 46.447529 -46.6434 46.5153 -48.6723 59.948521 -44.6144 51.3939 -48.6723 34.526567 -47.6579 31.879696 -48.6723 26.489458 -47.6579 32.824725 -44.6144 60.393646 -37.5131 44.089667 -47.6579 -- Marcelle Soares-Santos http://home.fnal.gov/~marcelle/ http://www.darkenergysurvey.org/