AstroNote 2025-127

ZTF25aagfhmz/AT2025cyj was first detected by ZTF on 2025-02-16 as an alert with a detection of g = 20.01 mag, and reported as a transient to TNS on 2025-02-28. The transient was rising at the time of discovery and flagged by the tdescore ML classifier as a TDE candidate on 2025-03-19. It has remained persistently blue (g-r = -0.21 mag) since discovery with no clear color evolution. Forced photometry reveals additional early detections of this source, beginning 2024-10-31, with similar evolution and color. We obtained an initial pre-peak spectrum on 2025-03-21 with the Kast spectrograph mounted on the Shane 3-m telescope (PI: Chornock), which revealed a continuum bluer than the archival SDSS host galaxy spectrum (z = 0.144). An additional spectrum was obtained with the SOAR Goodman High Throughput Spectrograph (PI: Andreoni) on 2025-03-22, which revealed a similar blue continuum. We obtained another spectrum with the Low Resolution Imaging Spectrometer (LRIS) at Keck-I on 2025-04-27 (PI: Ravi). Upon SDSS host spectrum subtraction, the LRIS spectrum reveals a steep, blue continuum with no obvious emission features. With this spectrum, coupled with the persistent blue light curve, we classify ZTF25aagfhmz/AT2025cyj as a likely TDE. The long rise time (>60 days) and the lack of obvious spectral features may imply that this event is a member of the TDE-featureless class (Hammerstein+2023; doi: 10.3847/1538-4357/aca283). Swift UVOT/XRT observations have been requested.

ZTF25aaknwwy/AT2025hee was first detected by ZTF on 2025-03-24 as an alert with a detection of g = 20.10 mag, and reported as a transient to TNS on 2025-03-24. Forced photometry reveals additional early detections of this source, with a rise beginning on 2025-02-21, with similar evolution and color. The transient was flagged by the tdescore ML classifier as a TDE candidate on 2025-04-10. It has remained persistently blue (g-r = -0.76 mag) since discovery with no clear color evolution. We obtained an initial pre-peak spectrum on 2025-04-23 with the Kast spectrograph  (PI: Chornock), which revealed a continuum bluer than the archival SDSS host galaxy spectrum (z = 0.087). We obtained another spectrum with LRIS on 2025-04-27 (PI: Chornock). Upon SDSS host spectrum subtraction, the spectrum revealed a steep blue continuum and a broad He II/N III feature. With this spectrum, coupled with the persistent blue light curve, we classify ZTF25aaknwwy/AT2025hee as TDE-He. Swift UVOT/XRT observations have been requested.

ZTF25aagrecw/AT2025gmz was first detected by ZTF on 2025-02-19 as an alert with a detection of r = 20.71 mag, and reported as a transient to TNS on 2025-02-19. Forced photometry reveals additional early detections of this source beginning on 2025-02-17, with similar evolution and color. The transient was flagged by the tdescore ML classifier as a TDE candidate on 2025-02-24. It has remained persistently blue (g-r = -0.33 mag) since discovery with no clear color evolution. We obtained a spectrum with LRIS on 2025-04-27 (PI: Chornock), which revealed a steep blue continuum and no obvious emission features, consistent with the TDE-featureless class. Host stellar absorption lines confirm the redshift to be z = 0.459. With this spectrum, coupled with the blue light curve and lack of obvious AGN signatures, we classify ZTF25aagrecw/AT2025gmz as TDE-featureless. Swift UVOT/XRT observations have been requested.

Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Award #2407588 and a partnership including Caltech, USA; Caltech/IPAC, USA; University of Maryland, USA; University of California, Berkeley, USA; University of Wisconsin at Milwaukee, USA; Cornell University, USA; Drexel University, USA; University of North Carolina at Chapel Hill, USA; Institute of Science and Technology, Austria; National Central University, Taiwan; Operations are conducted by Caltech's Optical Observatory (COO), Caltech/IPAC, and the University of Washington at Seattle, USA.