[vsnet-grb-info 13188] GRB 130427A: KAIT optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14525
SUBJECT: GRB 130427A: KAIT optical observations
DATE:    13/05/02 07:17:53 GMT
FROM:    Weikang Zheng at U.of Michigan  <zwk at umich.edu>

WeiKang Zheng, S. Bradley Cenko, Alexei V. Filippenko and Adam Morgan
(UC Berkeley) report on behalf of the KAIT GRB team:

We observed the afterglow of GRB 130427A (e.g., Maselli et al., GCN
14448; Elenin et al., GCN 14450; Perley, GCN 14451) with the 0.76-m
Katzman Automatic Imaging Telescope (KAIT) located at Lick Observatory
on Apr. 28, 29, 30, and May 1 UT. Observations were carried out in the
B, V, R, and I filters. A series of images, lasting for about an hour,
was taken on each night. The afterglow is well detected in all filters,
and the estimated R-band magnitudes (calibrated to SDSS, transformed to
R) are as follows, with times relative to the BAT trigger:

t_mid(hr) exp(s) R(mag) err

20.2 60.0 17.4 +/- 0.1
45.1 60.0 18.5 +/- 0.1
69.1 360.0 19.1 +/- 0.1
93.1 600.0 19.6 +/- 0.2

A power-law fit to the data shows the afterglow continues to decay with
an index of roughly -1.0 (Itoh et al., GCN 14486).

Further observations are planned.