GCN Circular 9275
Subject
GRB 090424: Continued R-band monitoring
Event
Date
2009-04-28T02:18:53Z (17 years ago)
From
Myungshin Im at Seoul Nat U <mim@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.