[vsnet-grb-info 17118] GRB 151022A: Kanata/HOWPol optical observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18439
SUBJECT: GRB 151022A: Kanata/HOWPol optical observation
DATE:    15/10/22 15:10:33 GMT
FROM:    Koji Kawabata at HASC,Hiroshima U  <kawabtkj at hiroshima-u.ac.jp>

K. S. Kawabata, R. Itoh, T. Nakaoka, M. Yoshida (Hiroshima Univ.), K. Tsumura
(Tohoku Univ.), and K. Arimatsu (NAOJ) report on behalf of Kanata team:

We performed a series of optical imaging-polarimetry for the optical afterglow 
of GRB151022A (D'Avanzo et al., GCN 18436) from 119 sec after the Swift/BAT 
trigger with HOWPol attached to the 1.5-m Kanata telescope at Higashi-Hiroshima
Observatory, Japan.

We could not detect any afterglow within the XRT error circle reported in the 
GCN 18436. We obtained the following preliminary upper limits (3-sigma) in our 
first image (mid-time 134 sec after the trigger) calibrated with UCAC4:

Rc > 17.0

Further analysis is ongoing.