[vsnet-grb-info 7721] GRB 090424: Continued R-band monitoring

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9275
SUBJECT: GRB 090424: Continued R-band monitoring
DATE:    09/04/28 02:18:53 GMT
FROM:    Myungshin Im at Seoul Nat U  <mim at astro.snu.ac.kr>

  M. Im, Y. Jeon, W. Park, I. Lee (CEOU/Seoul National Univ),
  Y.-B. Jeon (KASI) and Y. Urata (NCU) on behalf of EAFON team.

   We continued our follow-up observation of GRB090424
  (Cannizo et al. GCN 9223) in R using the 1.0m telescope
  at Mt. Lemmon (Arizona, US) operated by the Korea Astronomy
  Space Science Institute.
   The R-band imaging started at 2009 April 27, 02:57:33 UT.
   The mid-point of the R-band obseravation is April 27,
  03:45:21 UT (61.55 hrs after the burst).

   From a stacked image of 20 frames (3 min exp. each),
  we clearly detect the afterglow at R=21.7 +- 0.3 mag.
   Note that this value includes the flux (R ~ 22.2 mag)
  of the host or foreground galaxy at the location of
  the GRB noted by Evans et al. (GCN 9226).
   The trend of the fading, corrected for the galaxy light
  contamination, is consistent with a steep decay of flux
  reported earlier (Im et al. GCN 9253).
   The photometry was calibrated against USNO-B1 stars in
  the vicinity of GRB.

    Mid-point            Rmag      Rmag
   (hrs after burst)               (excluding the galaxy light)
-----------------------------------------------------
     14.97           19.9+-0.14    20.0
     37.45           21.0+-0.17    21.4
     61.55           21.7+-0.30    22.8

   We thank the LOAO operator, I. Baek for her assistance for this
  observation.