TITLE:   GCN CIRCULAR
NUMBER:  14393
SUBJECT: GRB 130418A: LOAO Observation
DATE:    13/04/19 14:34:07 GMT
FROM:    Myungshin Im at Seoul Nat U  <mim@astro.snu.ac.kr>

M. Im (CEOU/SNU), H.-I. Sung(KASI), and Y. Urata (NCU) 
on behalf of EAFON

  We observed the field of GRB 130418A (Pasquale et al., GCN 14377) 
in R, I, and z filters using the 1-m telescope at Mt. Lemmon 
observatory in Arizona, US.

  The observation started at 2013-04-19 03:40 UT, 
or about 8.6 hours after the BAT alert, and continued for
about 45 min. We clearly identify the fading afterglow in
R- and I-band, at the location reported earlier (Gorosabel et al.
GCN 14378; Quadri et al. GCN 14379; de Ugarte Postigo et al. GCN14380; 
D'Avanzo et al. GCN 14381; Klotz et al. GCN14382; Kuin et al.
GCN14384; Tello et al. GCN 14385; Nardini et al. GCN 14386; 
Perley et al. GCN 14387; Butler et al. GCN 14388; Covino et al.
GCN 14389; Kruehler et al. GCN 14390). On the other hand,
the detection in z-band is marginal.

  Preliminary magnitudes of the afterglow, calibrated against 
a USNO B-1 star at RA=140.047350 and Dec=+13.655828 are given below:

   T(mid, UT)         Mag
04-19 03:58:26     R=18.95 +- 0.07
04-19 04:04:16     I=18.18 +- 0.08

  We thank the LOAO operator, Jae-Hyuk Yoon for performing 
the observation.