TITLE: GCN CIRCULAR NUMBER: 39345 SUBJECT: GRB 250215A: Swift/UVOT Upper Limits DATE: 25/02/16 15:30:21 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 field of GRB 250215A detected by Fermi, the Einstein Probe and INTEGRAL (GCN Circ. 39327; Wang et al., GCN Circ. 39329; Barria et al., GCN Circ. 39331) 19.5 ks after the trigger. The afterglow reported in the XRT (Page et al., GCN Circ. 39336) and optical/IR (Liu et al., GCN Circ. 39330; Xie et al., GCN Cic. 39333; Malesani et al., GCN Circ. 39339) is not detected in the single U-band exposure. This is consistent with the redshift of z=4.61 reported by Sanchez-Ramirez et al. (GCN Circ. 39343).
Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposure is:
Filter T_start(s) T_stop(s) Exp(s) Mag
u 9504 16104 1704 >21.06
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.056 in the direction of the burst (Schlegel et al. 1998).
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