TITLE:   GCN CIRCULAR
NUMBER:  40952
SUBJECT: GRBs 250702B/C/D/E / EP250702a: Swift/UVOT  Upper Limits
DATE:    25/07/04 14:09:07 GMT
FROM:    Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>

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).