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ASAS-SN Discovery of Bright Nuclear Transients in PGC 069190 and 2dFGRS S588Z294

ATel #6521; E. Conseil (Association Francaise des Observateurs d'Etoiles Variables), S. Kiyota (Variable Star Observers League in Japan), J. Brimacombe (Coral Towers Observatory), C. Gonzalez, C. Contreras (Las Campanas Observatory), E. Y. Hsiao (Aarhus University), T. W.-S. Holoien, K. Z. Stanek, C. S. Kochanek, A. B. Davis, U. Basu, J. F. Beacom (Ohio State), B. J. Shappee (Hubble Fellow, Carnegie Observatories), J. L. Prieto (Diego Portales, MAS), D. Bersier (LJMU), D. Szczygiel, G. Pojmanski (Warsaw University Observatory), I. Cruz (Cruz Observatory), J. Hissong (Columbus Astronomical Society), L. A.G. Monard (Klein Karoo Observatory), J. Nicolas (Groupe SNAUDE, France), B. Nicholls (Mt. Vernon Obs., New Zealand), W. Wiethoff (University of Minnesota, Duluth)
on 1 Oct 2014; 18:57 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 #: 6536

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the double 14-cm "Cassius" telescope in Cerro Tololo, Chile, we discovered two new transient sources located near the nuclei of the galaxies PGC 069190 and 2dFGRS S588Z294:

 
Object       RA (J2000)     DEC (J2000)      Disc. UT Date   Disc. V mag 
ASASSN-14ih  22:34:29.81   -24:39:52.39      2014-09-19.14     16.6 
ASASSN-14ii  22:16:40.78   -36:09:39.93      2014-09-22.14     16.6 

ASASSN-14ih was discovered in images obtained on UT 2014-09-19.19 at V~16.6 mag. We also detect the object in images obtained on UT 2014-09-15.16 (V~16.9), UT 2014-09-17.15 (V~16.5), UT 2014-09-24.13 (V~16.4), UT 2014-09-26.13 (V~17), UT 2014-09-28.13 (V~16.8), and UT 2014-09-30.14 (V~16.9). We do not detect (V>17.3) the object in images taken on UT 2014-08-27.19 and before. Images obtained by E. Conseil on UT 2014-09-28.86 using a 0.35-m Slooh Space robotic telescope T2 at Mt. Teide, Canary Islands, by S. Kiyota on UT 2014-09-29.40 using a 0.5m CDK + FLI PL-9000 at the ITelescope.NET site at Siding Springs Observatory, and on UT 2014-09-30.05 with the LCO Swope 1-m telescope confirm increased flux from the host galaxy's central region but do not show a resolved source distinct from the host nucleus. This figure shows the 2014-09-30 Swope 1-m V-band follow-up image (left) and the archival DSS image of the host (right). The red circle has a radius of 1" and is centered on the position of the transient.

ASASSN-14ii was discovered in images obtained on UT 2014-09-22.14 at V~16.6 mag. We also detect the object in images obtained on UT 2014-09-21.14 (V~16.8), UT 2014-09-24.13 (V~16.9), UT 2014-09-26.12 (V~17.1), and UT 2014-09-30.04 (V~16.8). We do not detect (V>17.3) the object in images taken on UT 2014-09-20.14 and before. Images obtained by E. Conseil on UT 2014-09-28.37 using the 0.35-m Slooh Space robotic telescope T2 at Mt. Teide, Canary Islands, by J. Brimacombe on UT 2014-09-29.45 with the RCOS 41-cm telescope near Siding Spring Observatory, and by S. Kiyota on UT 2014-09-29.49 using a 0.5m CDK + FLI PL-9000 at the ITelescope.NET site at Siding Springs Observatory confirm increased flux from the host galaxy's central region but do not show a resolved source distinct from the host nucleus. This figure shows the 2014-09-29 S. Kiyota follow-up image (left) and the archival DSS image of the host (right). The red circle has a radius of 1" and is centered on the position of the transient.

The position of ASASSN-14ih is approx. 0.2" from the center of the galaxy PGC 069190 (z=0.033466, d=137 Mpc, via NED), and the position of ASASSN-14ii is approx. 0.8" from the center of the galaxy 2dFGRS S588Z294 (z=0.0308, d=126 Mpc, via NED). Neither host appears to have spectra indicative of an AGN in NED. At the host distances, ASASSN-14ih would have an absolute V-band magnitude of approx. -19.1 (m-M=35.68, A_V=0.057) and ASASSN-14ii would have an absolute V-band magnitude of approx. -19.0 (m-M=35.5, A_V=0.059). We conclude these transients are likely supernovae, but given the proximity to the host nuclei, unusual AGN activity or a tidal disruption events cannot be ruled out.

Follow-up observations of both transients, particularly spectroscopy, 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.