AstroNote 2025-116

TDE2025chm was classified as a TDE at z=0.101 on TNS Classification Report No. 20496 by Charalampopoulos 2025. WFST first detected the transient as WFST0520gbwr in the wide field survey on February 18, 2025 (UTC), recording a g-band magnitude of 20.00+/-0.08 (MJD 60724.61) and an r-band magnitude of 20.30+/-0.09 (MJD 60724.7). We proposed Swift monitoring campaign and XRT detected a fast rising X-ray brightening on March 31, 2025, with a count rate of 0.05 cts/s and an unabsorbed luminosity of approximately 1e44 erg/s (assuming a redshift of 0.101), making it the X-ray brightest one among all optically selected thermal TDEs. Observations from XRT and EP/FXT indicate that it has maintained a high luminosity for two weeks without any obvious signs of decay, while the light curve exhibits distinct variability on a timescale of days. The stacked X-ray spectrum during the rising phase is soft and is well fitted by a multicolor disk blackbody model with a temperature of approximately 90 eV.

Further multiwavelength follow-up observations have been scheduled, including campaigns with Mephisto, Swift, XMM-Newton, and NICER.

This report is based on observations obtained with the 2.5-m Wide Field Survey Telescope (WFST) at Mt. Saishiteng, Lenghu, China. The WFST science products have been made possible through the contributions of the University of Science and Technology of China (USTC) and the Purple Mountain Observatory (PMO).