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ASASSN-17cq and ASASSN-17cs: Discovery of Two Probable Supernovae

ATel #10108; J. Brimacombe (Coral Towers Observatory), P. Cacella (DogsHeaven Observatory), S. Kiyota (Variable Star Observers League in Japan), J. S. Brown, K. Z. Stanek, T. W.-S. Holoien, C. S. Kochanek, J. Shields, T. A. Thompson (Ohio State), B. J. Shappee (Hubble Fellow, Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), D. Bersier (LJMU), Subo Dong, S. Bose, Ping Chen (KIAA-PKU), J. M. Fernandez (Observatory Inmaculada del Molino), R. S. Post (Post Astronomy)
on 22 Feb 2017; 00:48 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Jonathan Brown (brown@astronomy.ohio-state.edu)

Subjects: Optical, Supernovae, Transient

Referred to by ATel #: 10112, 10131

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 two new transient sources, most likely supernovae, in an uncatalogued galaxy and ESO 015-G 010.

ASASSN-17cq (AT 2017axl) was discovered in images obtained on UT 2017-02-18.22 at V~16.9 mag. We do not detect (V>17.4) the object in images taken on UT 2017-02-17.22 and before. An image obtained on 2017-02-20 by J. Brimacombe 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-17cq is approximately 0.68" South and 0.50" East from the center of an uncatalogued galaxy (no information available from NED).

ASASSN-17cs (AT 2017azw) was discovered in images obtained on UT 2017-02-21.02 at V~16.4 mag. We do not detect (V>17.5) the object in images taken on UT 2017-02-18.02 and before. An image obtained on 2017-02-21 by P. Cacella confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the P. Cacella confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the P. Cacella image.

The position of ASASSN-17cs is approximately 6.0" North and 0.3" East from the center of the galaxy ESO 015-G 010 (no redshift information available from NED). Properties of the new source and photometry are summarized in the tables below: Properties of the new source 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-17cq  06:15:55.494   -55:56:51.66     2017-02-18.22      16.9            N/A                 0.84 
ASASSN-17cs  04:22:50.186   -82:04:11.11     2017-02-21.02      16.4            N/A                 6.01 
ASASSN-17cq photometry:
 
Obs. UT Date         V mag 
2017-02-17.22        >17.4 
2017-02-18.22         16.9 
ASASSN-17cs photometry:
 
Obs. UT Date         V mag 
2017-02-18.02        >17.5 
2017-02-21.02         16.4 

Follow-up observations are encouraged.

While we are participating in the TNS system to minimize potential confusion, ASAS-SN will continue using ASASSN-17xx 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-17xx (AT 2017xyz) 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 Center for Cosmology and AstroParticle Physics (CCAPP) at OSU, the Chinese Academy of Sciences South America Center for Astronomy (CASSACA), and the Mt. Cuba Astronomical Foundation. For more information about the ASAS-SN project, see the ASAS-SN Homepage and the list of all ASAS-SN transients.