TITLE: GCN CIRCULAR NUMBER: 40294 SUBJECT: GRB 250430A: Kanata optical upper limit DATE: 25/04/30 18:52:29 GMT FROM: Koji Kawabata at HASC,Hiroshima U kawabtkj@hiroshima-u.ac.jp
K. S. Kawabata, T. Hori, T. Nakaoka (Hiroshima Univ.) report on behalf of Kanata team:
We performed optical imaging polarimetry to the field of the GRB 180720B (Parsotan et al. GCN 40292; Lipunov et al. GCN 40291) from 2025-04-30 17:34:03 UT (162 seconds after the trigger) with HONIR attached to the 1.5-m Kanata telescope at Higashi-Hiroshima Observatory, Japan. We did not detect any new optical source up to a limiting magnitude of Rc = 16.0 (3-sigma; Vega mag) at the position of the UVOT source in our first 30 second exposure.
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