TITLE: GCN CIRCULAR NUMBER: 40750 SUBJECT: SVOM sb25061207: AbAO AS-32 Optical Upper Limit DATE: 25/06/16 18:56:01 GMT FROM: Nicolai Pankov at HSE, IKI RAS colinsergesen@gmail.com
N. Pankov (HSE, IKI), A. Pozanenko (IKI), R. Ya. Inasaridze (AbAO) report on behalf of IKI-GRB-FuN:
We performed optical observations of the field of an X-Ray transient sb25061207 (Zhang et. al, GCN 40697; Evans et. al, GCN 40711; Song et. al, GCN 40718) using the 0.7-meter AS-32 telescope of the Abastumani Astrophysical Observatory (AbAO). The observations began on 2025-06-12 at 17:42:06 UT, i.e. ~0.32 days since the SVOM trigger. The series of images has taken in the R-band. We do not detect the optical counterpart (Li et. al, GCN 40707) in the stacked image of 65*60 sec. The preliminary upper limit is given below:
Date UT start t-T0 Exp. Filter OT Err. UL (mid, days) (n*s) (3sigma) 2025-06-12 17:42:06 0.32447 65*60 R n/d n/d 20.0
The photometry has calibrated using nearby stars from USNO-B1.0 (R2 magnitudes) and has not corrected for the Galactic extinction. The result is in agreement with optical upper limits reported by (Becerra et. al, GCN 40723; Li et. al, GCN 40731; Adami et. al, GCN 40744).
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