AT2025wap (ZTF25abkgjzb) was first detected at a position (J2000) of:
RA = 21:07:28.29 (316.867857 deg)
Dec = +14:08:17.21 (14.138115 deg)
on 2025 Aug 21 07:12:00 UTC by ZTF at g = 20.61 +/- 0.19 mag (MJD=60908.30). The transient brightened rapidly by 0.9 magnitudes the next night, to g = 19.74 +/- 0.14 (MJD=60909.30). No ZTF r-band detections were reported as alerts, but forced photometry recovered a detection at r = 21.49 +/- 0.33 mag (MJD=60908.24), 1.4 hours before discovery. Forced photometry also recovered post-peak r-band measurements, but we do not report them here as they are less reliable than the contemporaneous LT imaging we obtained.
LT follow-up observations revealed detections at g = 20.34 +/- 0.12 (MJD=60911.17) and g = 20.74 +/- 0.16 (MJD=60911.97), indicating a g-band fade rate of ~0.4 mag/day since the observed peak. LT also recovered a single i-band and multiple r-band detections that confirmed a fast fade.
The Galactic latitude of AT2025wap is -21.8 degrees, with a line-of-sight extinction of E(B-V) = 0.10 (Schlafly & Finkbeiner 2011). After correcting for extinction, the color at discovery was g-r = -1.0 +/- 0.4 mag, indicating a blue source. A very faint, extended, optical counterpart is present in Legacy Survey DR10.
The rapid evolution and blue colors motivated us to trigger Swift XRT/UVOT. 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.
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