{
  "bibcode": "2000GCN...587....1K",
  "body": "Naoto Kobayashi (Subaru Telescope, National Astronomical Observatory of Japan),\nMiwa Goto, Hiroshi Terada (Kyoto University),\nAlan T. Tokunaga (Institute for Astronomy, University of Hawaii),\non behalf of SUBARU Telescope team and SUBARU IRCS team\n\n\nWe report an improved near-infrared photometry of the proposed OT for\nGRB000301C in our J,H,K' images taken with IRCS (InfraRed Camera and\nSpectrograph) on the SUBARU Telescope on March 3.55 UT. Photometry was\nperformed on co-added image (18-min total exposure time) while quick\nphotometry of one K' frame (2-min exposure) was reported in GCNC #577. \nSeeing was approximately 0.45\" in K' and 0.50\" in J/H throughout the\nobservation. The OT magnitudes were determined with about 0.01 mag\nstatistical accuracy in all bands.\n\nRelative magnitudes of the OT to the near-by bright star (5.7\" W and\n1\" S) were derived and compared to the results by Rhoads & Fruchter\n(GCN #586) to examine possible near-infrared decay of the OT. The\nresults are as follows:\n\n                   relative magnitude(OT-Star)      Reference\n                     J         H       K'  \nUT 3.55 March      2.27      2.18    1.56           this work\nUT 4.64 March      2.47      ----    1.69           GCNC #586\n\n   decay/day       0.20      ----    0.13\n\nSince we expect the uncertainty of relative photometry is quite small\n(e.g., 0.01 mag), these results suggest that the OT is actually fading\nin the near-infrared. The near-infrared decay rate is smaller compared\nto the R-band decay rate (~0.4-mag/day) of the same period. The\nslightly larger decay in J compared to K' may suggest that the decay\nrate is smaller in longer wavelengths.\n\nThe possible host galaxy reported by Rhoads & Fruchter (GCN #586) is\nalso detected in our images. It looks slightly extended\n(FWHM=0\".6-0\".7) in our K'-images of 0\".45 seeing, which suggests\nthat this source is actually a galaxy.\n\nThis message is quotable in publications.",
  "circularId": 587,
  "createdOn": 952266816000,
  "email": "naoto@naoj.org",
  "subject": "GRB000301C, near-infrared observations (JHK' imaging)",
  "submitter": "Naoto Kobayashi at SUBARU, NAOJ  <naoto@naoj.org>",
  "eventId": "GRB 000301C"
}