TITLE: GCN CIRCULAR NUMBER: 18744 SUBJECT: LIGO/Virgo G211117: DESGW program observations with DECam DATE: 15/12/29 04:16:09 GMT FROM: M. Soares-Santos at Fermi Lab M. Soares-Santos (Fermilab), A. Rest (STSCI), D. James (CTIO/NOAO), D. J. Brout (UPenn), J. Annis (Fermilab), E. Berger (Harvard), H.-Y. Chen (UChicago), P. Cowperthwaite (Harvard), H. T. Diehl (Fermilab), B. Farr (UChicago), D. A. Finley (Fermilab), J. Frieman (Fermilab/UChicago), R. Gruendl (NCSA), D. Holz (UChicago), R. Kessler (UChicago), K. Herner (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 4-m telescope at CTIO on the night of 2015-12-27 in response to the LVC trigger G211117/G211182. These observations are part of a plan to observe about 90 sq-deg of the region of interest (the subregion that is visible from CTIO) and cover a total of about 10% of the total LVC probability. DECam has a 3 sq-deg field of view, and typically reaches i,z = 23rd limiting magnitudes for 90 sec exposure times. If an optical counterpart of magnitude ~23 or brighter, is present within the imaged area, our observing strategy allows us to achieve ~90% detection probability. Coordinates observed in the first night are given below. More observations are planned for upcoming nights. Analysis is underway. ra dec 29.932371 2.0517 25.168446 -3.0207 26.75595 -2.0063 37.708542 13.20445 34.568587 9.14855 23.617796 -6.0642 -- Marcelle Soares-Santos http://home.fnal.gov/~marcelle/ http://www.darkenergysurvey.org/