SALT spectroscopic classification of nuclear transients Gaia17cen/AT2017gld as SN Ia-91T

ATel #10738; N. Ihanec (University of Nova Gorica), M. Gromadzki, L. Wyrzykowski (Warsaw University Astronomical Observatory, Poland), D. A. H. Buckley (South African Astronomical Observatory)
on 12 Sep 2017; 10:09 UT
Credential Certification: Lukasz Wyrzykowski (wyrzykow@astrouw.edu.pl)

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We report on SALT spectroscopy of transient Gaia17cen/AT2017gld, discovered by the Gaia Science Alerts program on 2017-09-02. The transient was detected in the nucleus of the host galaxy. A low resolution (R = 350) SALT/RSS spectra was taken on 2017-09-10, under the SALT Large Programme on transients (2016-2-LSP-001).

The spectroscopic classification was done using SNID code (Blondin & Tonry 2007, ApJ, 666, 1024) and it was matched to SN Type Ia-91T at about 15 days past maximum. Spectrum shows clear narrow emission Halpha line which is present due to the nucleus of the host galaxy and corresponds to redshift 0.0768. Gaia photometric measurement near the maximum brightness at this redshift corresponds to absolute magnitude of about -19.1 mag, also consistent with SN Type Ia.

Name | IAU name | RA (J2000) | Dec (J2000) | Disc. Date | Disc. Mag | Obs. Date | z | Host | Type | Notes
Gaia17cen | AT2017gld | 05:05:44.39 | -23:23:50.93 | 2017-09-02 | 18.46 | 2017-09-10 | 0.0768 | GALEXASC J050544.48-232351.7 | SN Ia-91T | +15 days

We acknowledge ESA Gaia, DPAC and the Photometric Science Alerts Team (http://gsaweb.ast.cam.ac.uk/alerts).