{
  "bibcode": "2011GCN.12132....1B",
  "body": "E. Berger (Harvard) reports on behalf of a larger collaboration:\n\n\"Additional inspection and photometry of our Gemini-South r-band image (GCN\n12128) reveals a second, fainter source (S2) at the following coordinates\n(J2000):\n\nRA = 10:58:36.955\nDEC = -23:27:20.62\n\nwith an uncertainty of about 0.8\" (due to centroid uncertainty).  This\nposition is consistent with the faint source detected by GROND (GCN 12129).\n\nPhotometry of the two sources using the Gemini-South/GMOS standard\nphotometric zero-point yields the following magnitudes:\n\nS1:  r = 21.28+/-0.05 mag (\"DSS\" source)\nS2:  r = 22.18+/-0.12 mag\n\nTaken at face value, the brightness of S2 is consistent with the GROND value\n(r=22.15+/-0.15 mag; GCN 12129), suggesting that S1 has actually faded by\nabout 0.3+/-0.15 mag between 1 and 3.2 hours after the initial trigger.\n\nAlternatively, if the offset relative to the GROND photometry of S1\n(r=20.9+/-0.1 mag) is due to a zero-point offset, the resulting brightness\nof S2 is r = 21.9+/-0.1 mag.  This is marginally consistent with the GROND\nvalue (r=22.15+/-0.15 mag) which was obtained about 2.2 hours earlier than\nour observations.\n\nTo determine which scenario is correct relative to the GROND photometry, we\nmeasure the brightness of the star at:\n\nRA = 10:58:38.053\nDEC = -23:26:31.78\n\nto be r = 18.25 mag.\"",
  "circularId": 12132,
  "createdOn": 1310263822000,
  "email": "eberger@cfa.harvard.edu",
  "subject": "GRB 110709B: Gemini-South additional analysis and photometry",
  "submitter": "Edo Berger at Harvard  <eberger@cfa.harvard.edu>",
  "eventId": "GRB 110709B"
}