GCN Circular 42959
Subject
GRB251129A/EP251129a: Swift UVOT detection
Event
Date
2025-12-02T18:31:14Z (6 days ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
Via
email
N.P.M. Kuin (UCL-MSSL) and B. Cenko (NASA/GSFC) report on behalf of the
Swift/UVOT team:
The Swift/UVOT began observations of the field of GRB 251129A 16.8 ks
after the SVOM trigger (Tan et al., GCN Circ. 42877). GRB251129A was
also detected
by the EP (Wu et al, GCN Circ. 16828).
The optical afterglow consistent with the SVOM/COLIBRI position (Angulo et
al. GCN Circ. 42880; Watson, GCN Circ. 42883) is detected in the initial
UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld
et al. 2011, AIP Conf. Proc. 1358, 373) are::
Filter T_start(s) T_stop(s) Exp(s) Mag
white 16828 17147 315 19.63 +/- 0.07
white 27564 28089 502 19.69 +/- 0.12
white 111007 117142 1044 20.22 +/- 0.12
white 227072 234439 2745 20.92 +/- 0.17
u 16503 16823 315 20.06 +/-
0.30
The magnitudes in the table are not corrected for the Galactic extinction due
to the reddening of E(B-V) = 0.025 in the direction of the burst (Schlegel
et al. 1998).