TITLE: GCN CIRCULAR NUMBER: 38882 SUBJECT: EP250109a: Swift/UVOT non-detection DATE: 25/01/09 23:46:29 GMT FROM: Sam Shilling at Lancaster University shilling.sam@gmail.com

S. P. R. Shilling (Lancaster U.), S. R. Oates (Lancaster U.), A. A. Breeveld (UCL-MSSL) and N. P. M. Kuin (UCL-MSSL) report on behalf of the Swift UVOT team:

Swift/UVOT observed the field of EP250109a (Li et al., GCN 38864) for 938 seconds in the U-band starting at 09:22:16 UT, 3 hours after the detection by Einstein Probe WXT.

No optical afterglow is detected within a 5" radius of the EP FXT position (Li et al., GCN 38864) to a preliminary 3-sigma U-band upper limit of >20.6, calculated using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373).

The non-detection reported here is consistent with the non-detections reported in other optical observations using the GOTO (Kumar et al., GCN 38868), MASTER (Lipunov et al., GCN 38871), and the SVOM/VT in one of the two filters (Qiu et al., GCN 38872).

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