{
  "bibcode": "2001GCN..1164....1P",
  "body": "M. M. Phillips (Carnegie), K. Krisciunas (CTIO), P. M. Garnavich,\nS. Holland (Notre Dame), S. Jha, K. Z. Stanek (Harvard-Smithsonian\nCfA) and P. McCarthy (Carnegie) report:\n\nWe have observed the field of GRB 011121 with the 6.5m Magellan I\nBaade telescope (+ IR imager) on UT 2001 Nov 29.3 for a total of \n4320s in the Js passband with 0.5\" seeing in the combined image.\n\nA finder chart of the combined image is available at:\nhttp://cfa-www.harvard.edu/cfa/oir/Research/GRB/.\n\nThe data have been calibrated via three IR standard stars also\nobserved over the course of the night, from the list of Persson et al.\n(1998, AJ, 116, 2475). The Js passband is slightly narrower than the\nstandard J, but we make no color correction and adopt Js = J because\nwe lack sufficient data (both for the standard stars and the objects\nin the GRB field). The effects of the slight filter mismatch are\nexpected to be small (see, for example, Krisciunas et al. 2001, AJ,\n122, 1616). For the bright stars marked in the finder, we measure J =\n17.82 +/- 0.03 (star D) and J = 18.59 +/- 0.03 (star E).\n\nA source at the position of the GRB afterglow is marginally detected,\nbut because of its faintness, it is difficult to separate a possible\npoint source from the underlying fuzz. Differential PSF-fitting\nphotometry relative to the bright stars in the field yields J = 21.9\n+/- 0.1 for the source at the position of the GRB afterglow. Because\nof the marginal detection, this should be viewed as an upper limit.\n\nTwo other sources are detected near the GRB position. One bright\nsource is located 0.8\"S and 2.0\"E of the GRB with J = 19.98 +/- 0.04.\nThis object may be the core of the GRB host galaxy, but it is not\nclearly resolved -- it might be a foreground star. The other source\n(the \"blob\") located 1.6\"S and 2.6\" E of the GRB is clearly detected\nat J = 21.57 +/- 0.07, and is possibly extended.\n\nAdopting J ~ 16 mag for the GRB afterglow on Nov 22.36 (GCN 1153), the\nreported optical decay slope (GCN 1160) would predict J ~ 21 for the\nafterglow at the time of these observations.\n\nThis message may be cited.",
  "circularId": 1164,
  "createdOn": 1007075595000,
  "email": "sjha@cfa.harvard.edu",
  "subject": "GRB 011121: J-band observations",
  "submitter": "Saurabh Jha at Harvard-Smithsonian CfA  <sjha@cfa.harvard.edu>",
  "eventId": "GRB 011121"
}