{
  "bibcode": "2010GCN.10690....1C",
  "body": "S. B. Cenko, A. N. Morgan, and J. S. Bloom (UC Berkeley) report on behalf\nof a larger collaboration:\n\nWe have obtained further imaging of the field of GRB 100424A (Hoversten et\nal., GCN 10667) with the Near InfraRed Imager and Spectrometer mounted on\nthe 8 m Gemini North telescope.  Following our report of a detection of a\ncandidate afterglow in the J and K filters (Cenko et al., GCN 10682), we\nobtained a sequence of H-band images beginning at 9:29 UT on 25 April 2010\n(~ 17 hours after the burst).\n\nThe candidate afterglow is also detected in the H-band.  Using the\nPAIRITEL imaging of the field for photometric calibration (Morgan and\nBloom, GCN 10675), we measure a magnitude of H = 20.9 (Vega) at this time.\n\nCombined with our previous J and K photometry (and assuming the afterglow\ndecays in time like a power-law with index alpha=-1), the candidate\ninfrared afterglow appears consistent with a relatively steep spectral\npower-law index of beta ~ 2.5-3.0 across all three bands.  This suggests\nthe afterglow is reddened due predominantly to dust in the host galaxy of\nthe GRB, and not an extremely high-redshift (z > 7) origin, as would be\nsuggested by the presence of host galaxy extinction from the X-ray\nafterglow spectrum (Stroh et al., GCN 10674).\n\nWe wish to thank the staff at Gemini Observatory for assistance in\nexecuting these observations.",
  "circularId": 10690,
  "createdOn": 1272266865000,
  "email": "cenko@srl.caltech.edu",
  "subject": "GRB 100424A: Gemini/NIRI H-band observations",
  "submitter": "S. Bradley Cenko at Caltech  <cenko@srl.caltech.edu>",
  "eventId": "GRB 100424A"
}