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Spectroscopic confirmation of the dwarf nova nature of GR Orionis

ATel #4811; Akira Arai (Nishi-Harima Astronomical Observatory, University of Hyogo), Daisaku Nogami(Kyoto University) on behalf of the Optical and Infrared Synergetic Telescopes for Education and Research (OISTER)
on 14 Feb 2013; 12:40 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Akira Arai (arai@nhao.jp)

Subjects: Optical, Cataclysmic Variable, Nova, Transient, Variables

We spectroscopically observed GR Ori with the 2.0-m Nayuta Telescope at Nishi-Harima Astronomical Observatory on 2013 February 13. This observation was carried out with the low resolution mode (R~1,000) of the optical spectrograph MALLS which covers the wavelength of 4,000-6,800 A. GR Ori was discovered as a possible nova in 1916 (Thiele 1916, Astron. Nachr., 202, 213), but has long been suspected to be a dwarf nova (e.g. McLaughlin 1945, AJ, 51, 136; Kato et al. 2012, PASJ, 64, 63). The second outburst of GR Ori was found by R. Stubbings on 2013 Feb. 11.476 (UT) at 13.0 mag (vsnet-outburst 15096). Our spectra of this star obtained around 2013 Feb. 13.53 (UT) have a blue continuum showing H-alpha in absorption with an emission core, H-beta in absorption (FWZI~1,800 km/s), and possibly He I 5876 in emission, which give evidence of the dwarf nova nature of GR Ori. Follow-up observations are being continued by OISTER.