TITLE: GCN CIRCULAR NUMBER: 38542 SUBJECT: GRB 241207A: TSHAO Zeiss-1000 optical observations DATE: 24/12/12 14:19:10 GMT FROM: Nicolai Pankov at HSE, IKI RAS colinsergesen@gmail.com
N. Pankov (HSE, IKI), I. Reva (FAI), M. Krugov (FAI), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN:
We performed optical observations of GRB 241207A (Fermi GBM team, GCN 38454; V.Lipunov et. al, GCN 38459; McKenna et. al, GCN 38536) in the R filter with 1-meter Zeiss-1000 telescope of Tien-Shan observatory (TSHAO). The observations began on 2024-12-07 13:04:43 UT, i.e. ~0.17 days since trigger. Using STDWeb (Karpov, 2024) ZOGY-based image subtraction against ZTF DR7 we did not find an optical candidate transient in the median stacked images of the fields:
FieldID RA Dec Width Height (hr) (deg) (arcmin) 1 19:15:05 +42:01:05 19.03 19.03 2 19:09:58 +42:29:55 19.03 19.03
The preliminary upper limits are as follows:
Date UT start t-T0 Exp. Filter OT Err. UL(3sigma) FieldID (mid, days) (s) 2024-12-07 13:04:43 0.176087 4*90 R n/d n/d 20.3 1 2024-12-07 13:15:56 0.206782 48*90 R n/d n/d 20.8 2
The magnitudes were calibrated using nearby stars from USNO-B1.0 (R2 magnitudes) and are not corrected for the Galactic extinction towards the GRB 241207A.
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