ASASSN-19vj: Discovery of A Possible Hostless Supernova
J. Brimacombe (Coral Towers Observatory), B. Nicholls (Mt. Vernon Obs., New Zealand), P. Vallely, K. Z. Stanek, C. S. Kochanek, C. M. Basinger, Z. Way, 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, S. Holmbo (Aarhus)
During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014), using data from the quadruple 14-cm "Cassius" telescope in Cerro Tololo, Chile, we discovered a new transient source on the rise.

ASASSN-19vj (AT 2019ozb) was discovered in images obtained on UT 2019-08-29.99 at g~17.5 mag. We do not detect (g>18.5) the object in images taken on UT 2019-08-24.00 and before. An image obtained on 2019-08-30 confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the confirmation image.

The position of ASASSN-19vj is over 2' away from the nearest galaxy listed on NED, and there is no source coincident with the transient listed on VizieR. This indicates that this event is a hostless supernova, but spectroscopic follow-up will be required to completely rule out the possibility that it is a CV. Properties of the new source and photometry are summarized in the tables below:

Follow-up observations are strongly encouraged.

While we are participating in the TNS system to minimize potential confusion, ASAS-SN will continue using ASASSN-19xx transient names as our primary nomenclature (including supernovae, but also other classes of transients), and we encourage others to do the same. We prefer merging the names as ASASSN-19xx (AT 2019xyz) to preserve, rather than anonymize, the origin of the transient.

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, the Chinese Academy of Sciences South America Center for Astronomy (CASSACA), and the Villum Fonden (Denmark). For more information about the ASAS-SN project, see the ASAS-SN Homepage and the list of all ASAS-SN transients.
optical,supernovae,transient