GCN Circular 40952
Subject
GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
Event
Date
2025-07-04T14:09:07Z (4 months ago)
From
Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>
Via
Web form
M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the Einstein Probe (GCN Circ. 40906) location of the source that showed repeated outbursts detected by Fermi/GBM (GCN Circ. 40883, 40885, 40886, 40890, 40891) and Swift/BAT-GUANO (GCN #40903) 82 ks after the initial EP detection. No optical afterglow consistent with the XRT position (Kennea et al., GCN Circ. 40919) 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) using the initial EP detection as T_0 are:
Filter T_start(s) T_stop(s) Exp(s) Mag
b 82576 99156 235 >19.83
uvm2 99570 99822 247 >19.33
u 82491 104859 302 >19.73
v 82985 99566 115 >18.44
uvw1 82327 104787 628 >19.93
uvw2 82661 99481 663 >20.12
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.27 in the direction of the burst
(Schlegel et al. 1998).