ASASSN-16oe: A Very Bright, Unusual Transient Near the Galactic Plane
ATel #9860; J. Strader, L. Chomiuk (MSU), K. Z. Stanek, J. S. Brown, 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. Brimacombe (Coral Towers Observatory)
on 14 Dec 2016; 20:39 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Krzysztof Stanek (stanek.32@osu.edu)
Subjects: Optical, Transient
Referred to by ATel #: 9879
During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or
"Assassin"), using data from the quadruple 14-cm "Cassius" telescope
in Cerro Tololo, Chile, we discovered a new transient source, of
unknown nature, close to the Galactic plane
ASASSN-16oe was discovered in images obtained on UT 2016-11-30.35 at
V~13.3 mag, and the outburst is detected in several epochs before and
after (light curve plot). This object is not in
outburst in images taken on UT 2016-08-21.97 and before (the field
containing this transient only recently became observable from behind
the Sun, which is why there is a gap in our observations.) ASAS-SN has
been observing this region of the sky since 2016-02-09.
At the position of the transient Vizier reports a red match, 1.3"
away, with photographic USNO magnitudes B=17.4, R=15.7, and also a
Gaia DR1 match with G=15.9. We obtained a revised position of
RA=12:46:20.147, DEC=-58:53:38.87 from the spectroscopy acquisition
images, which matches the Gaia object position to
0.04". vsnet-alert
20448 reports observations in three bands by J. Hambsch, stating
that the "object is red (B-V = +0.8) and is likely a reddened
nova."
Given these observations, we obtained a spectrum (covering 380-780 nm)
with the Goodman spectrograph on the SOAR telescope on UT
2016-12-12.29. The spectrum shows absorption
lines characteristic of an F star, with Balmer and some metal
lines. No emission lines or broad absorption lines are apparent, hence
this source is not a nova or a dwarf nova. Given its location and
light curve, ASASSN-16oe might be a disk microlensing event.
The position of ASASSN-16oe is approximately 4 degrees away from the
Galactic plane (l=302.268, b=3.97). Properties of the new
source and photometry are summarized in the tables below:
Object RA (J2000) DEC (J2000) Disc. UT Date Disc. V mag
ASASSN-16oe 12:46:20.147 -58:53:38.87 2016-11-30.35 13.3
Obs. UT Date V mag sig_V
2016-08-21.97 15.8 0.20
2016-11-29.35 13.4 0.03
2016-11-30.35 13.3 0.02
2016-12-07.36 13.4 0.03
2016-12-08.34 13.5 0.02
2016-12-10.34 13.7 0.02
2016-12-13.36 14.0 0.07
Follow-up observations are encouraged.
We thank Las Cumbres Observatory and its staff for their continued
support of ASAS-SN. ASAS-SN is supported by 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.
ASAS-SN Light Curve of ASASSN-16oe