ASAS-SN Discovery of ASASSN-18dw, a 4+ Magnitudes Stellar Outburst Towards Orion

ATel #11359; K. Z. Stanek, C. S. Kochanek, J. V. Shields, T. A. Thompson (OSU), 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 26 Feb 2018; 17:30 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 "Leavitt" telescope in Fort Davis, Texas, the quadruple 14-cm "Payne-Gaposchkin" telescope in Sutherland, South Africa, and the quadruple 14-cm "Paczynski" telescope in Cerro Tololo, Chile, we detect a bright, rapidly raising transient source

 
Object       RA (J2000)    DEC (J2000)      Disc. UT Date   Disc. g mag  
ASASSN-18dw  06:02:04.77  -12:19:50.8       2018-02-25.14     14.3 

ASASSN-18dw was discovered in images obtained on UT 2018-02-25.14 at g~14.3. We also detect this source on UT 2018-02-24.087 (g~15.8), UT 2018-02-24.169 (g~15.3), UT 2018-02-25.88 (g~13.8) and UT 2018-02-26.20 (g~13.6). We do not detect (g>17.6) this object in g-band subtracted images taken on UT 2018-02-23.18 and before. The position of ASASSN-18dw matches to a reddish PS1 g=18.6, r=17.8 source in the vicinity of the Orion star forming region (there are also numerous Vizier matches to other catalogs, including Gaia and GALEX).

We have retrieved image subtraction photometry time series at the location of ASASSN-18dw in both V-band and g-band. No previous outbursts or variability are detected at the position of ASASSN-18dw since ASAS-SN started observing this location in October 2013.

Follow-up observations, especially spectroscopy, 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).