{
  "bibcode": "2009GCN..9253....1I",
  "body": "M. Im, W. Park, Y. Jeon, I. Lee (CEOU/Seoul National Univ),\n  Y.-B. Jeon (KASI) and Y. Urata (NCU) on behalf of EAFON team.\n\n   We continued the follow-up observation of GRB090424 (Cannizzo et al.\n  GCN 9223) in BVR using the 1.0m telescope at Mt. Lemmon (Arizona, US)\n  operated by the Korea Astronomy Space Science Institute.\n   The R-band imaging started at 2009 April 26, 03:11:23 UT.\n   The mid-point of the R-band obseravation is April 26,\n  03:39:43 UT (37.45 hrs after the burst).\n\n   From a stacked image of 13 frames (3 min exp. each),\n  the afterglow is visible at R=20.96 +- 0.17 mag, suggesting\n  a significant fading occurred since last night (Im et al. GCN 9248),\n  more than the expected amount of fading with the power-law index\n  of 0.71 reported earlier (Urata et al. GCN 9247). This suggests that\n  jet break might have occured. The afterglow is also visible in\n  B- and V-bands.\n   The photometry was calibrated against USNO-B1 stars in the vicinity.\n\n   We thank the LOAO operator, J. Yoon for his assistance for this\n  observation.",
  "circularId": 9253,
  "createdOn": 1240745429000,
  "email": "mim@astro.snu.ac.kr",
  "subject": "GRB090424: R-band detection (37.5 hrs post-burst), jet break?",
  "submitter": "Myungshin Im at Seoul Nat U  <mim@astro.snu.ac.kr>",
  "eventId": "GRB 090424"
}