GCN Circular 12791

Subject

GRB 111228A: LOAO Optical Observation

Event

Date

2011-12-31T11:58:29Z (14 years ago)

From

Myungshin Im at Seoul Nat U <mim@astro.snu.ac.kr>

Yiseul Jeon, Myungshin Im, Minsung Jang (CEOU/Seoul National
  Univ.), and Yuji Urata (NCU) on behalf of a larger collaboration

  We observed GRB 111228A (Ukwatta et al., GCN 12737Loading...
 
 ) in
  B- and R-bands with a 1 m telescope at Mt. Lemmon, Arizona, US.

  The observation started at 2011-12-30 08:03:16 UT,
  or 1.7 days after the BAT aleart. We detected the afterglow
  in the images taken with both filters.
  Using the the photometry calibration based on an USNO B1 star
  USNO-B1 1083-0199833 with B=18.85 and R=17.28 following Klotz et al.
  (GCN 12746Loading...
 
 ), we find the following.

  Filter Mid-Time[UT] Mid-Time[Since BAT] Mag
  B-band 2011-12-30 08:33:55 40.82 hours 21.75+-0.14
  R-band 2011-12-30 10:41:29 42.95 hours 20.67+-0.09

  Further observation is ongoing. We thank the LOAO operator,
  J. Yoon for his help with the observation.