ASASSN-19wf: Discovery of A Bright Type Ia Supernova in the TESS Field
ATel #13093; J. Brimacombe (Coral Towers Observatory), 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), I. Cruz (Cruz Observatory)
on 9 Sep 2019; 15:42 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Patrick Vallely (vallely.7@osu.edu)
Subjects: Optical, Supernovae, Transient
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, we discovered a new supernovae in the galaxy VII Zw 923. The transient lies within the Camera 2 field of the ongoing TESS Sector 15 observations per the Web TESS Viewing Tool, and will also be observed by TESS during the 2 upcoming sectors.
ASASSN-19wf (AT 2019pkz) was discovered in images obtained on UT 2019-09-04.25 at g~17.2 mag. We do not detect (g>18.2) the object in images taken on UT 2019-08-29.38 and before. An image obtained on 2019-09-05 confirms the discovery of the transient. This figure shows the archival SDSS g-band image of the field (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-19wf is approximately 0.3" South and 0.1" West from the center of the galaxy VII Zw 923. A classification spectrum obtained by SCAT on 2019-09-06.33 indicates that this is a Type Ia supernova about one week before maximum light at a redshift of z~0.05. This corresponds to a luminosity distance of d=213.4 Mpc, giving an absolute g-band magnitude of approximately -19.7 (m-M=36.65, A_g=0.247). Properties of the new source and photometry are summarized in the tables below:
Object RA (J2000) DEC (J2000) Disc. UT Date Disc. g mag Approx. Abs. Mag Offset from Host (")
ASASSN-19wf 19:58:29.588 +61:13:08.76 2019-09-04.25 17.2 -19.7 0.32
Obs. UT Date g mag
2019-08-29.38 >18.2
2019-09-04.25 17.2
Additional follow-up observations are 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.
