GCN Circular 36168
Subject
GRB 240418A: TSHAO Zeiss-1000 optical upper limit
Date
2024-04-19T01:36:41Z (15 days ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
Via
legacy email
A. Pozanenko (IKI), I. Reva (FAI), N.Pankov (HSE), S. Belkin (IKI) report on behalf of GRB-IKI-FuN:
We have observed the field of GRB 240418A (Siegel et al., GCN 36162) with Zeiss-1000 telescope of Tien Shan Astronomical Observatory starting on 2024-04-18 (UT) 21:47:25.
We do not detect any object within Enhanced Swift-XRT position (Evans et al., GCN 36166) up to R=21.6. Preliminary photometry of the field in a stacked image is following.
Date UT start t-T0 Filter Exp. OT Err. UL(3 sigma)
(mid, days) (s)
2024-04-18 21:47:25 - R 21*120 n/d n/d 21.6
The photometry is based on nearby USNO-B1.0 stars.
Non detection of the OT is in agreement with the observations (Lipunov et al., GCN 36163; Odeh et al., GCN 36165; Malesani et al., GCN 36167).