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ASAS-SN Discovery and Spectroscopic Classification of a Type Ia Supernova in SDSS J130814.58+620201.2

ATel #6219; T. W.-S. Holoien (Ohio State), R. M. Wagner, A. Kaur, A. Porter (Clemson), A. Wilber (ASU), J. L. Prieto (Princeton), B. J. Shappee, A. B. Davis, K. Z. Stanek, C. S. Kochanek, J. Jencson, U. Basu, J. F. Beacom (Ohio State), D. Szczygiel, G. Pojmanski (Warsaw University Observatory), J. Brimacombe (Coral Towers Observatory), D. Bersier (LJMU), C. E. Woodward (Minnesota), S. G. Starrfield (ASU), D. Hartman (Clemson)
on 9 Jun 2014; 19:14 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Thomas Holoien (tholoien@astronomy.ohio-state.edu)

Subjects: Optical, Supernovae, Transient

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the quadruple 14-cm "Brutus" telescope in Haleakala, Hawaii, we discovered a new supernova in SDSS J130814.58+620201.2.

Object       RA (J2000)     DEC (J2000)      Disc. UT Date   Disc. V mag 
ASASSN-14cb  13:08:14.24    +62:02:00.9      2014-06-07.33     16.7    

ASASSN-14cb was discovered in images obtained 2014 UT June 07.33 at V~16.7 mag. We also detect the object in images obtained on UT June 08.31 (V~17) and UT June 09.31 (V~16.9), but we do not detect this object (V>17) in images taken on 2014 UT June 06.31 and before. Images and spectra obtained on UT June 09.21 with the 2.4m Hilter telescope at the MDM observatory confirm the detection of the transient. This figure shows the ASAS-SN reference image (top left), ASAS-SN June 07 discovery subtraction image (top right), archival SDSS g-band image (bottom left), and the MDM confirmation image (bottom right). The red circle has a radius of 5.0" at the position of the SN.

The ASAS-SN position of ASASSN-14cb is approximately 0.1" South and 2.5" East of the core of SDSS J130814.58+620201.2 (z=0.033643, d=143 Mpc, via NED), which would give it an absolute V mag of approx. -19.1 at discovery (m-M=35.78, A_V=0.035, Schlafly & Finkbeiner 2011).

We obtained optical spectra of ASASSN-14cb with the MDM 2.4m + OSMOS (range 4000-6850 Angs., res. 3 Angs.) on UT June 09.21. The spectrum of ASASSN-14cb shows characteristics of a normal Type Ia SN at or before maximum light. After correcting for the redshift of the host galaxy, we measure the blueshifted velocity of the Si II 6355 line at v~-11000 km/s.

Follow-up observations are encouraged.

We thank LCOGT and its staff for their continued support of ASAS-SN. For more information about the ASAS-SN project, see the ASAS-SN Homepage and the list of all ASAS-SN transients.