TITLE: GCN CIRCULAR NUMBER: 40012 SUBJECT: GRB 250314A: ALMA detection DATE: 25/04/02 20:20:24 GMT FROM: Tanmoy Laskar at U of Utah tanmoylaskar@gmail.com
T. Laskar (University of Utah), R. Margutti, R. Chornock, Nayana A. J. (UC Berkeley), K. D. Alexander (University of Arizona), and H. Sears (Rutgers University) report:
“We observed the high-redshift (z ~ 7.3; Malesani et al., GCN 39732; Rakotondrainibe et al., GCN 39743) SVOM/ECLAIRs GRB 250314A (Wang et al., GCN 39719) with the Atacama Large Millimeter/Submillimeter Array (ALMA) beginning on 2025 March 26 02:55 UTC (11.6 days after the burst) at multiple frequencies.
Preliminary analysis reveals a mm source with flux density of ~ 40 microJy at 42 GHz at position:
RA (J2000) = 13:25:12.14 Dec (J2000) = -05:16:55.29
with an uncertainty of 0.18" in each coordinate. This is consistent with the optical position (Malesani et al., GCN 39727) and radio position (Nayana A. J. et al., GCN 39954). We note that GRBs 250314A and 090423 (z ~ 8.2; Tanvir et al., Nature, 461, 7268, 1254; Castro Tirado et al., GCN 9273; de Ugarte Postigo et al., A&A, 538, A44, 2012) are the highest-redshift GRBs with mm-band detections so far. Further ALMA observations are planned.
We thank the ALMA Director for rapidly granting our DDT request and the JAO staff, AoD, P2G, and the entire ALMA team for their help with these observations."
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