AstroNote 2025-297

AT2025zow (ZTF25abvalml) was first detected at a position (J2000) of:

RA = 02:23:20.91 (35.837134 deg)

Dec = +32:06:08.62 (+32.102395 deg)

on 2025 Oct 02 08:23:45 UTC by ZTF at g = 19.16 +/- 0.09 mag (MJD=60950.35). The transient was flagged for its sharp rise in g from a forced photometry upper limit at g = 20.79 mag (MJD=60949.41), rising at a rate of ~1.6 mag/day. A detection by ZTF at g = 19.74 +/- 0.09 mag (MJD=50951.41) indicates the transient then faded rapidly by ~0.6 mag/day. No ZTF r band detections were reported as alerts, but forced photometry received a detection on Oct 02 at r = 19.81 +/- 0.07 mag (MJD=50951.48).

LT observations on 2025 October 04 at g = 20.71 +/- 0.22 mag (MJD=60952.10) confirm further fading. On Oct 05, LT reported a limit at g = 20.59 mag (MJD=60952.99). 

The Galactic latitude of AT2025zow is -26.86 deg, with a line-of-sight extinction of E(B-V) = 0.08 (Schlafly & Finkbeiner 2011). An optical counterpart is present in Legacy Survey DR10, SDSS and PAN-STARRS. The counterpart is a barred spiral galaxy in SDSS, with a photo-z of 0.035 ± 0.008, yielding an absolute magnitude for this transient of M = -16.2 to -17.2 mag. The transient is spatially coincident with the bright nucleus of the galaxy, though there is no evidence of AGN activity, past variability, or anomalous WISE colors.

We encourage further follow-up observations.

ZTF is supported by the National Science Foundation under Grant No. AST-2034437 and a collaboration including Caltech, IPAC, the Oskar Klein Center at Stockholm University, the University of Maryland, University of California, Berkeley, the University of Wisconsin at Milwaukee, University of Warwick, Ruhr University Bochum, Cornell University, Northwestern University and Drexel University. Operations are conducted by COO, IPAC, and UW.

The Liverpool Telescope is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council.