TITLE:   GCN CIRCULAR
NUMBER:  9244
SUBJECT: GRB090423: Y-band limit
DATE:    09/04/25 04:12:16 GMT
FROM:    Myungshin Im at Seoul Nat U  <mim@astro.snu.ac.kr>

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

   We took a series of Y-band images of GRB090423 using the 1.0m
  telescope at Mt. Lemmon (Arizona, US) operated by the Korea Astronomy
  Space Science Institute.

   We do not detect the afterglow in a stacked image with the
  total exposure time of 78 min, placing an upper limit of Y < 19.8 (Vega)
  at 3-sigma at the mid point of UT April 24, 06:16. The photometry
  calibration was done using the calibration data reported
  in Im et al. (GCN 9242, 9221).

  We thank the LOAO operator, J. Yoon for his assistance for this
  observation.