TITLE: GCN CIRCULAR NUMBER: 39654 SUBJECT: GRB 250309B / AT2025dws: KMTNet-CTIO optical observations DATE: 25/03/10 16:46:17 GMT FROM: Min-Su Shin at Korea Astronomy and Space Science Institute msshin@kasi.re.kr
Min-Su Shin (Korea Astronomy and Space Science Institute; KASI), Jae-Woo Kim (KASI), and Seo-Won Chang (Seoul National University) report on behalf of the KMTNet neutrino ToO program:
We observed the area corresponding to the neutrino event IceCube-250309A with the KMTNet-CTIO for the initial coordinates of Zegarelli et. al, GCN 39631.
The KMTNet-CTIO observation started at 2025-03-09 09:44 (UTC), and we acquired I-band images for four pointings covering the entire 90% uncertainty area for the alert. The source AT2025dws (Stein et al., GCN 39639, Pérez-Fournon et al. GCN 39643, Moskvitin et al. GCN 39645, Perley et al. GCN 39646) is clearly found in the images with the following photometric measurements:
MJD mag err 60743.40574 17.88 0.02 60743.40723 17.87 0.02
We thank the KMTNet operators for their support.
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