ASAS-SN Discovery of a Very Bright (g~10.1) Transient ASASSN-18su

ATel #11968; K. Z. Stanek, C. S. Kochanek, J. V. Shields, T. A. Thompson (OSU), L. Chomiuk, J. Strader (MSU), B. J. Shappee (IfA-Hawaii), T. W.-S. Holoien (Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), Subo Dong (KIAA-PKU), M. Stritzinger (Aarhus)
on 18 Aug 2018; 17:43 UT
Distributed as an Instant Email Notice Transients
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 "Payne-Gaposchkin" telescope in Sutherland, South Africa, we detect a very bright, new transient source, likely an outburst of a nearby cataclysmic variable

 
Object       RA (J2000)    DEC (J2000)    Disc. UT Date   Disc. g mag  
ASASSN-18su  12:57:51.258  -28:30:16.82   2018-08-17.71    10.1 

ASASSN-18su was discovered in images obtained on UT 2018-08-17.71 at g~10.1, and it is also detected at V~10.0 on UT 2018-08-17.97. We do not detect (V>18.0) this object in subtracted images taken on UT 2018-08-14.98 and before.

Using ASAS-SN Sky Patrol light curve interface (Kochanek et al. 2017), we have retrieved aperture photometry time series at the location of ASASSN-18su in the last 30 days, and the resulting V-band light curve can be seen here. No previous outbursts are detected at the position of ASASSN-18su since ASAS-SN started observing this location in December 2013.

Follow-up observations, especially spectroscopy and rapid cadence photometry, are strongly 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).