ASASSN-19lb: Detection of an Unusual Stellar Outburst in the TESS FOV
ATel #12703; T. Jayasinghe, K. Z. Stanek, C. S. Kochanek, P. Vallely, J. V. Shields, T. A. Thompson (OSU), B. J. Shappee (Univ. of Hawaii), T. W.-S. Holoien (Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), Subo Dong (KIAA-PKU), M. Stritzinger (Aarhus)
on 29 Apr 2019; 18:11 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Tharindu Jayasinghe (jayasinghearachchilage.1@osu.edu)
Subjects: Optical, Star, Transient
During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014, Kochanek et al. 2017), using data from the quadruple 14-cm "Cassius" and "Paczynski" (CTIO) telescopes, we identified an unusual stellar outburst towards the Galactic plane in the TESS FOV. The source ASASSN-19lb (position from Gaia DR2, RAJ2000=174.95582, DEJ2000=-70.67553, source_id=5233532175492716032, G~15.7, d~1.7 kpc, l=297.02598, b= -08.62943) was first observed by ASAS-SN on UT 2015-07-18. Presently, ASASSN-19lb has more than ~2300 data points and has been observed ~800 times in the past ~200 days.
The source ASASSN-19lb had a quiescent mean magnitude of g~15.6. The latest ASAS-SN photometry shows that ASASSN-19lb gradually faded to g~16.3 at UT 2019-04-12.1 before the outburst event that brightened the source to g~14.8 at UT 2019-04-23.2. We also see evidence for a small dimming episode to g~16.0 at UT 2019-01-27.3. This source is currently fading as of UT 2019-04-28.8. We do not identify similar outbursts in the previous ASAS-SN V/g-band photometry . ASASSN-19lb is currently being observed by TESS as part of its sector 11 observations. Additional follow-up observations are strongly encouraged.
We 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, and the Chinese Academy of Sciences South America Center for Astronomy (CASSACA). For more information about the ASAS-SN project, see the ASAS-SN Homepage and the list of all ASAS-SN transients .
