ASAS-SN Discovery of an Unprecedented >1.5 Magnitude Optical Flare from QSO B0346-279

ATel #11337; P. Vallely, K. Z. Stanek, C. S. Kochanek, J. V. Shields, T. A. Thompson (Ohio State), B. J. Shappee (IfA-Hawaii), T. W.-S. Holoien (Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), D. Bersier (LJMU), Subo Dong, S. Bose, Ping Chen (KIAA-PKU), M. Stritzinger (Aarhus)
on 22 Feb 2018; 21:37 UT
Credential Certification: Krzysztof Stanek (stanek.32@osu.edu)

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During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014), using data from the quadruple 14-cm "Brutus" telescope in Haleakala, Hawaii, the quadruple 14-cm "Leavitt" telescope in Fort Davis, Texas, the quadruple 14-cm "Payne-Gaposchkin" telescope in Sutherland, South Africa, and the quadruple 14-cm "Cassius" and "Paczynski" telescopes in Cerro Tololo, Chile, we have discovered an unprecedented optical brightening of QSO B0346-279 (z~0.9874).

QSO B0346-279, while optically variable in CRTS data, was never seen to be brighter than V~17.5. Its g-band magnitude in Gaia data is g=18.7 and its PS1 brightness is g=19.8. In archival ASAS-SN data going back to February 2013 it is not seen to be brighter than V~17 until the onset of this flaring event. QSO B0346-279 reached a V-band magnitude of V=15.5 on UT 2018-02-21.08 (g=16.4 on UT 2018-02-17.09), decaying to V=15.8 on UT 2018-02-22.07. Such a dramatic brightening is unprecedented for this object. V and g-band photometric observations of this ongoing event are shown here.

Follow-up observations are encouraged.

We would like to thank Las Cumbres Observatory and its staff for their continued support of ASAS-SN. ASAS-SN is funded in part by the Gordon and Betty Moore Foundation through grant GBMF5490 to the Ohio State University, NSF grant AST-1515927, the Mt. Cuba Astronomical Foundation, the Center for Cosmology and AstroParticle Physics (CCAPP) at OSU, the Chinese Academy of Sciences South America Center for Astronomy (CASSACA), and the Villum Fonden (Denmark).