ASAS-SN Discovery of A Likely Galactic Nova ASASSN-17gk on the Rise

ATel #10387; K. Z. Stanek, C. S. Kochanek (OSU), L. Chomiuk, J. Strader (MSU), J. S. Brown, T. W.-S. Holoien, J. V. Shields, T. A. Thompson (OSU), B. J. Shappee (Hubble Fellow, Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), D. Bersier (LJMU), Subo Dong, S. Bose, Ping Chen (KIAA-PKU), J. Brimacombe (Coral Towers Observatory)
on 18 May 2017; 00:49 UT
Distributed as an Instant Email Notice Novae
Credential Certification: Krzysztof Stanek (stanek.32@osu.edu)

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During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the quadruple 14-cm "Cassius" telescope in CTIO, Chile, we detect a very bright, new transient source, most likely a classical nova, near the Galactic plane

 
Object       RA (J2000)    DEC (J2000)    Gal l (deg)   Gal b (deg)    Disc. UT Date   Disc. V mag 
ASASSN-17gk  13:20:55.32   -63:42:18.5     306.187         -1.02         2017-05-17.28      10.9 

ASASSN-17gk was discovered in images obtained on 2017-05-17.28 at V~10.9, but it has been present in ASAS-SN data since 2017-04-25.08 (V~13.3), with significant shorter-timescale variability (V~11.6 on 2017-04-28.11 and V~12.05 on 2017-05-04.19). We do not detect (V>17.4) this object in subtracted images taken on UT 2017-04-23.16 and before. No previous outbursts are detected at this location since ASAS-SN started observing it in February 2016.

Follow-up observations, especially multi-band photometry and spectroscopy, 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).