{
  "bibcode": "2017GCN.21529....1C",
  "body": "D. A. Coulter, C. D. Kilpatrick, M. R. Siebert, R. J. Foley (UCSC), B. J.\nShappee, M. R. Drout, J. S. Simon, A. L. Piro (Carnegie), and A. Rest (STScI)\n\nreport on behalf of the One-Meter Two-Hemisphere (1M2H) collaboration:\n\nOn 2017 Aug 18 UT in the process of observing several galaxies coincident\nwith the highest-likelihood localization region for the LIGO/Virgo G298048\ntrigger (LVC GCNs 21509, 21513) with the 1-m Swope telescope at Las\nCampanas Observatory, we detect a source 5.3�� E and 8.8�� N of NGC 4993, an\nS0 galaxy in the NGC 4993 / ESO 508-G018 group at a distance of ~40 Mpc \n(Tully-Fisher distance to the group; Freedman et al., ApJ, 553, 47, 2001).\nThe object is:\n\nSSS17a  13:09:48.089  -23:22:53.35\n\nand had a brightness of i = 16.0 mag.\n\nWe have checked the minor planet center and previous SN discoveries, and\nhave found no cross-matches.  This source could possibly be optical\nemission associated with the LIGO/Virgo G298048 trigger. \n\nSpectroscopic observations are under way.  Additional photometry has been\nobtained and is being analyzed. Additional observations are encouraged.\n\nThe contact person for this circular is Ryan Foley (foley@ucsc.edu).\n\n[GCN OPS NOTE(28sep17):  Per a combination of requests and editorial\npolicy: (1) AR was added to the author list. (2) The contact-name sentence\nwas added.  The editor notes that RF was having sign-up problems with the\nLV-EM Forum and E.Berger offered to submit in his place since\npublication latency was important.  (3) And the EB signature block\nwas removed.]",
  "circularId": 21529,
  "createdOn": 1503018323000,
  "email": "eberger@cfa.harvard.edu",
  "subject": "LIGO/Virgo G298048: Potential optical counterpart discovered by Swope telescope",
  "submitter": "Edo Berger at Harvard U  <eberger@cfa.harvard.edu>",
  "eventId": "LIGO/Virgo G298048"
}