AT 2024wpp: An extremely luminous fast ultraviolet transient powered by accretion onto a black hole Perley, Daniel A Ho, Anna Y Q McGrath, Zoë Camilo, Michael Sevilla, Cassie Chen, Ping Schroeder, Genevieve Govreen-Segal, Taya Bochenek, Aleksandra Qin, Yu-Jing Gillanders, James H Amend, Benjamin Anderson, Joseph P Andreoni, Igor Aryan, Amar Bellm, Eric C Bloom, Joshua S de Boer, Thomas Carney, Jonathan Caiazzo, Ilaria ; https://orcid.org/0000-0002-4770-5388 Chambers, Ken C Charalampopoulos, Panos Chen, Ting-Wan Chen, Tracy X Coughlin, Eric R Coughlin, Michael Dennefeld, Michel Dimitriadis, Georgios Fremling, Christoffer Frostig, Danielle Gal-Yam, Avishay Galbany, Lluís Gangopadhyay, Anjashay Ghendrih, Melzie Graham, Matthew J Gromadzki, Mariusz Groom, Steven L Gutiérrez, Claudia P Hinds, K -Ryan Huber, Mark E Inserra, Cosimo Kaiser, Benjamin C Kasliwal, Mansi M Koivisto, Niilo E Lin, Chien-Cheng Liu, Chang Lowe, Thomas B Magnier, Eugene Mahabal, Ashish A Milligan, Andrew Minguez, Paloma Mo, Geoffrey Müller-Bravo, Tomás E Nicholl, Matt Pessi, Priscila J Pignata, Giuliano Purdum, Josiah Rehemtulla, Nabeel Rich, R Michael Sahu, Anwesha Singh, Avinash Smartt, Stephen J Smith, Ian A Sollerman, Jesper Srinivasaragavan, Gokul Srivastav, Shubham Stein, Robert D Schulze, Steve Tweddle, Jack W Wainscoat, Richard Wise, Jacob L Yan, Lin Young, David R stars: black holes supernovae: individual: AT2024wpp radio continuum: transients ddc:520 We present the discovery of AT 2024wpp (‘Whippet’), a fast and luminous 18cow-like transient. At a redshift of z = 0 . 0868 , revealed by Keck Cosmic Web Imager spectroscopy of its faint star-forming host, it is the fourth-nearest example of its class to date. Rapid identification of the source in the Zwicky Transient Facility data stream permitted ultraviolet-through- optical observations to be obtained prior to peak, allowing the first determination of the peak bolometric luminosity ( 2 ×1045 erg s−1 ), maximum photospheric radius ( 1015 cm), and total radiated energy ( 1051 erg) of an 18cow-like object. We present results from a comprehensive multiwavelength observing campaign, including a far-ultraviolet spectrum from the Cosmic Origins Spectrograph on the Hubble Space Telescope and deep imaging extending > 100 d post-explosion from the Very Large Telescope, Hubble Space Telescope , Very Large Array, and Atacama Large Millimetre Array. We interpret the observations under a model in which a rapidly accreting central engine blows a fast ( ∼0.2 c ) wind into the surrounding medium and irradiates it with X-rays. The high Doppler velocities and intense ionization within this wind prevent identifiable spectroscopic features from appearing in the ejecta or in the surrounding circumstellar material. Weak H and He signatures do emerge in the spectra after 35 d in the form of double-peaked narrow lines. Each peak is individually narrow (full width δv ∼3000 km s−1 ) but the two components are separated by v ∼6600 km s−1 , indicating stable structures of denser material, possibly representing streams of tidal ejecta or an ablated companion star. Oxford University Press 2026 info:eu-repo/semantics/article doc-type:article article http://purl.org/coar/resource_type/c_2df8fbb1 https://research-explorer.ista.ac.at/record/22303 https://research-explorer.ista.ac.at/download/22303/22314 Perley DA, Ho AYQ, McGrath Z, et al. AT 2024wpp: An extremely luminous fast ultraviolet transient powered by accretion onto a black hole. <i>Monthly Notices of the Royal Astronomical Society</i>. 2026;549(1). doi:<a href="https://doi.org/10.1093/mnras/stag678">10.1093/mnras/stag678</a> eng info:eu-repo/semantics/altIdentifier/doi/10.1093/mnras/stag678 info:eu-repo/semantics/altIdentifier/issn/0035-8711 info:eu-repo/semantics/altIdentifier/e-issn/1365-2966 info:eu-repo/semantics/altIdentifier/arxiv/2601.03337 info:eu-repo/semantics/openAccess