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PESSTO spectroscopic classification of optical transients

ATel #10212; M. Fraser (UCD), F. Onori (SRON), A. Hamanowicz (Warsaw), J. Anderson (ESO), C. Inserra (Southampton), E. Kankare (QUB), I. Manulis (Weizmann), K. Maguire (QUB), S. J. Smartt (QUB), K. W. Smith (QUB), M. Sullivan (Southampton), S. Valenti (UC Davis), O. Yaron (Weizmann), D. Young (QUB), J. Tonry, B. Stalder, L. Denneau., A. Heinze, H. Weiland (IfA, Univ. of Hawaii), A. Rest (STScI)
on 26 Mar 2017; 16:14 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Morgan Fraser (morgan.fraser@ucd.ie)

Subjects: Optical, Supernovae, Transient, Variables

Referred to by ATel #: 10225, 10240

PESSTO, the Public ESO Spectroscopic Survey for Transient Objects (see Smartt et al. 2015, A&A, 579, 40 http://www.pessto.org ), reports the following supernova classifications. Targets were supplied by the All Sky Automated Survey for SuperNovae ASAS-SN (see Shappee et al. 2014, ApJ, 788, 48 and http://www.astronomy.ohio-state.edu/~assassin/index.shtml ), the ATLAS survey (see Tonry et al., 2011, PASP, 123, 58) and from the ESA Gaia Photometric Science Alerts Team and DPAC (http://gsaweb.ast.cam.ac.uk/alerts). All observations were performed on the ESO New Technology Telescope at La Silla on 2017 March 25, using EFOSC2 and Grism 13 (3985-9315A, 18A resolution). Classifications were done with SNID (Blondin & Tonry, 2007, ApJ, 666, 1024) and GELATO (Harutyunyan et al., 2008, A&A, 488, 383). Classification spectra and additional details can be obtained from http://www.pessto.org (via WISeREP) and the IAU Transient Name Server.

 
Survey Name | IAU Name  | RA (J2000)  | Dec (J2000) | Disc. Date | Source  | Disc Mag | z     | Type   | Phase | Notes 
Gaia17atk   | AT2017cjx | 19:04:58.99 | -16:16:37.7 | 20170319   | Gaia    | 17.4     | -     | CV     | -     | 
ATLAS17cpj  | SN2017cfo | 10:38:12.91 | +28:07:02.0 | 20170317   | ATLAS   | 17.5     | 0.042 | SN?    | ?     | (1) 
ATLAS17dcj  | -         | 07:48:55.24 | -10:04:19.6 | 20170324   | ATLAS   | 17.4     | -     | CV     | -     | (2) 
Gaia17asu   | SN2017cir | 08:16:02.70 | -16:20:55.3 | 20170316   | Gaia    | 18.9     | 0.07  | Ia     | +3d   | 
ATLAS17bdx  | SN2017ben | 09:18:48.44 | -12:15:33.1 | 20170126   | ATLAS   | 19.5     | 0.036 | IIn    | >+20d | (3) 
ATLAS17dda  | SN2017cjv | 10:10:45.64 | -03:46:39.9 | 20170324   | ATLAS   | 17.9     | 0.06  | Ia     | ~0d   | 
ASASSN-17dm | AT2017cbg | 10:06:57.46 | -47:43:39.1 | 20170309   | ASASSN  | 16.3     | -     | M-star | -     | (4) 
ATLAS17cpk  | SN2017cfp | 15:21:11.51 | +25:46:41.9 | 20170317   | ATLAS   | 17.3     | 0.03  | Ia     | +5d   | 
ASASSN-17ea | SN2017cjr | 12:42:50.77 | -30:24:43.6 | 20170324   | ASASSN  | 16.2     | 0.02  | Ia     | -4d   | 
ATLAS17cog  | SN2017cfc | 13:52:38.99 | -02:00:08.2 | 20170316   | ATLAS   | 17.2     | 0.03  | Ia     | +3d   | 
ATLAS17dcd  | SN2017ckf | 12:57:49.32 | -24:43:10.8 | 20170319   | ATLAS   | 18.6     | 0.05  | Ia     | -3d   | 
ATLAS17byo  | SN2017cii | 16:33:19.80 | +23:43:51.6 | 20170314   | ATLAS   | 17.3     | 0.04  | Ia     | ~0d   | 
ATLAS17daf  | SN2017ciy | 17:04:06.89 | +25:03:09.9 | 20170314   | ATLAS   | 18.1     | 0.04  | Ia     | ~0d   | 

(1) The spectrum is blue and featureless. The redshift of the apparent host is 0.042 (from SDSS), implying an absolute magnitude at peak of -19.5. Consistent with this redshift, we detect very weak, narrow Halpha emission, likely from the host. A non-detection of the source from March 05 implies a rise time of <15 days. SLSNe Ic show a featureless spectrum around maximum, however, the absolute magnitude of SN2017cfo is considerably fainter than that of known SLSNe, and its rise time is faster. It is more likely a young, but luminous type II. Further spectra with PESSTO will be taken.
(2) Blue continuum, probable weak Balmer lines in the blue. Low galactic latitude strongly favours a CV.
(3) The spectrum shows a blue continuum, and strong narrow Balmer lines in emission. Unusually, the ratio between Halpha and Hbeta is ~1:1, while the rise time to peak (at absolute magnitude -17.4) appears relatively slow.
(4) A high signal-to-noise spectrum of the transient indicates it is an M-star or cool atmosphere. The transient is bright and clearly detected on our 20s V-band image, superimposed on resolved and extended flux. This flux is most likely from a nebula around a Galactic source (e.g. nova, or symbiotic star) and the system is in outburst. The extended flux does not have galaxy-like structure and was most likely erroneously classified as a galaxy.