TITLE: GCN CIRCULAR NUMBER: 45085 SUBJECT: IceCube260704A: OHP/T193 optical observations DATE: 26/07/06 10:52:28 GMT FROM: Christophe Adami at LAM <christophe.adami@lam.fr> C. Adami (LAM/Pytheas/AMU), S. Basa (LAM/OHP/Pytheas/AMU), E. Le Floc'h (CEA/Irfu), F. Schussler (CEA Paris-Saclay) report on behalf of a larger collaboration: We observed the WISEA J212302.62+340634.2 source (no available public spectroscopy in NED), at ~4.9arcmin from the mean coordinates of the IceCube event IceCube260704A (Zegarelli et al., GCN 45075), using the T193cm telescope at Observatoire de Haute-Provence (France) with the MISTRAL spectro-imager. We obtained 6 min of exposure in the r-band starting at 2026-07-05T02:04 UT (18.8h after the Zegarelli et al. trigger). In the preliminar stacked images, we do not detect significant magnitude change as compared to the PanStarrs r-band magnitude of r=18.05. We also observed in spectroscopic mode: - We obtained a total of 60 min of exposures (2 x 30min) with the MISTRAL spectroscopic blue setting from 4000 to 7800 AA, starting at 2026-07-05 00:18 UT (17h after the trigger). With a preliminar data reduction, we very clearly detect Halpha (apparently with a single peak) at a redshift of 0.1402. We also detect very clearly an intense double-peaked [NII]@6584A emission line. No other emission line are visible. We detect however Magnesium@5175A, CaFe@5269A and NaD@5892A in absorption. The log(Halpha/[NII]) is close to -0.1, likely placing this galaxy in the AGN/LINER region in a BPT diagram. The two peaks of the [NII] emission line are separated by ~300km/s. - We then obtained a second serie of 3 x 30min starting at 2026-07-05 23:13 UT (~40h after the trigger). With a preliminar data reduction, we still clearly detect Halpha with a single peak at the same redshift and with a similar intensity. The [NII]@6584A emission line may show a mild evolution: the flux is stronger and the two peaks are much less separated and proeminent. The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the STDWeb/STDPipe tools (Karpov 2025), is in the AB system, and is not corrected for Galactic extinction. We acknowledge the excellent support from Observatoire de Haute-Provence and in particular Jean Pierre Troncin. View this GCN Circular online at https://gcn.nasa.gov/circulars/45085. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...