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ASAS-SN Discovery of Two Probable Supernovae

ATel #8041; J. Brimacombe (Coral Towers Observatory), T. W.-S. Holoien, K. Z. Stanek, C. S. Kochanek, J. S. Brown, D. Godoy Rivera, G. Simonian, U. Basu, J. F. Beacom, T. A. Thompson (Ohio State), B. J. Shappee (Hubble Fellow, Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), D. Bersier (LJMU), Subo Dong, Ping Chen (KIAA-PKU), E. Falco (CfA), P. R. Wozniak (LANL), G. Pojmanski (Warsaw University Observatory), G. Bock (Runaway Bay Observatory, Australia), E. Conseil (Association Francaise des Observateurs d'Etoiles Variables), I. Cruz (Cruz Observatory), S. Kiyota (Variable Star Observers League in Japan), P. Marples (Leyburn Observatory, Australia) G. Masi (Virtual Telescope Project, Ceccano, Italy), B. Nicholls (Mt. Vernon Obs., New Zealand)
on 11 Sep 2015; 19:48 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Thomas Holoien (tholoien@astronomy.ohio-state.edu)

Subjects: Optical, Supernovae, Transient

Referred to by ATel #: 8072

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 two transient sources, most likely supernovae, in the galaxies 2MASX J01383676-0440581 and SDSS J040326.23-052930.6.

ASASSN-15pm was discovered in images obtained on UT 2015-09-11.56 at V~17.3 mag. We do not detect (V>17.3) the object in images taken on UT 2015-09-11.19 and before. An image obtained by J. Brimacombe on UT 2015-09-11.71 with the CDK 43-cm telescope at Savannah Skies Observatory confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the J. Brimacombe confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the J. Brimacombe image.

The position of ASASSN-15pm is approximately 9.9" North and 10.2" West from the center of the galaxy 2MASX J01383676-0440581 (z=0.048784, d=204 Mpc, via NED), giving an absolute V-band magnitude of approximately -19.3 (m-M=36.55, A_V=0.088).

ASASSN-15pn was discovered in images obtained on UT 2015-09-11.61 at V~17.7 mag. We do not detect (V>17.0) the object in images taken on UT 2015-09-11.27 and before. An image obtained by J. Brimacombe on UT 2015-09-11.72 with the CDK 43-cm telescope at Savannah Skies Observatory confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the J. Brimacombe confirmation image (right). The red circle has a radius of 3" and is centered on the position of the transient in the J. Brimacombe image.

The position of ASASSN-15pn is approximately 0.6" South and 1.3" East from the center of the galaxy SDSS J040326.23-052930.6 (z=0.038393, d=161 Mpc, via NED), giving an absolute V-band magnitude of approximately -18.6 (m-M=36.03, A_V=0.258).

Properties of the two sources and photometry are summarized in the tables below:

 
Object       RA (J2000)     DEC (J2000)      Disc. UT Date   Disc. V mag  Approx. Abs. Mag   Offset from Host (") 
ASASSN-15pm  01:38:36.08    -04:40:48.04      2015-09-11.56      17.3          -19.3               14.21 
ASASSN-15pn  04:03:26.32    -05:29:31.30      2015-09-11.61      17.7          -18.6               1.43 

ASASSN-15pm photometry:

 
Obs. UT Date         V mag 
2015-09-11.19        >17.3 
2015-09-11.56         17.3 

ASASSN-15pn photometry:

 
Obs. UT Date         V mag 
2015-09-11.27        >17.0 
2015-09-11.61         17.7 

Follow-up observations are encouraged.

We thank LCOGT and its staff for their continued support of ASAS-SN. ASAS-SN is supported by NSF grant AST-1515927, the Mt. Cuba Astronomical Foundation, and the Center for Cosmology and AstroParticle Physics (CCAPP) at OSU. For more information about the ASAS-SN project, see the ASAS-SN Homepage and the list of all ASAS-SN transients.