TITLE: GCN CIRCULAR NUMBER: 41059 SUBJECT: GRB 250702B,D,E / EP250702a: ALMA detection DATE: 25/07/10 18:59:43 GMT FROM: Kate D. Alexander at University of Arizona katedenhamalexander@gmail.com

Kate D. Alexander (U of Arizona), James Miller-Jones (Curtin U), Adelle Goodwin, (Curtin U), Noah Franz (U of Arizona), Raffaella Margutti (UC Berkeley) Ryan Chornock (UC Berkeley), Dheeraj Pasham (Eureka Scientific/George Washington), Edo Berger (Harvard), Yvette Cendes (U of Oregon), and Collin Christy (U of Arizona) report on behalf of a larger collaboration:

We observed the location of the unusual transient GRB 250702B,D,E / EP250702a (GCNs 40906, 40883, 40885, 40886, 40890, 40891) with the Atacama Large Millimeter/submillimeter Array (ALMA) at multiple frequencies (program 2023.1.01731.T, PI: Miller-Jones). On 2025 July 9 02:09:03 UT, 6.97 days after the first detection with the Einstein Probe (GCN 40906) and 6.51 days after the first Fermi trigger (GCN 40883), we clearly detected the source at a mean frequency of 97.5 GHz with a preliminary flux density of ~2 mJy. Further ALMA observations are planned.

We thank the ALMA staff for quickly scheduling these observations and for providing the quick-look reduction.

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