S. Parker, Canterbury, New Zealand, reports the discovery of an apparent supernova (red mag 15.5) on a 30-s unfiltered CCD image (limiting mag 18.5) taken by himself on 2014 Nov. 6.589 UT with an Officina Stellare 40-cm f/5.25 RiLA Astrograph (+ ST10 camera) at his Parkdale Observatory in the course of the Backyard Observatory Supernova Search. The new object is located at R.A. = 11h10m48s.41, Decl. = -37d27'02".2 (equinox 2000.0; reference stars from USNO-B and UCAC4 catalogues), which is 2" west and 10" south of the nucleus of the galaxy NGC 3568. Nothing is visible at this position on Digitized Sky Survey red and infrared images (limiting red mag > 19). An image of the variable was posted at website URL http://preview.tinyurl.com/k2ou5qf. The variable was designated PSN J11104841-3727022 when it was posted at the Central Bureau's TOCP webpage and is here designated SN 2014dw based on the spectroscopic confirmation reported below. I. Arcavi, G. Hosseinzadeh, S. Valenti, D. A. Howell and C. McCully, Las Cumbres Observatory Global Telescope Network and University of California, Santa Barbara, report that spectrograms of PSN J11104841-3727022 = SN 2014dw, obtained on 2014 Nov. 9.71 and 12.71 UT with the FLOYDS robotic spectrograph (range 320-1000 nm, resolution 2 nm) mounted on the 2-m "Faulkes Telescope South" at Siding Spring, show it to be a type-II supernova. Assuming the host-galaxy redshift of 0.00815 of Lauberts and Valentijn (1989, The Surface Photometry Catalogue of the ESO-Uppsala Galaxies; via NED), they find a possible high-velocity (blueshifted by about 18000 km/s from the rest wavelength), broad H-alpha absorption feature in addition to the "normal"- velocity feature around 7000 km/s. T. Diamond, Florida State University; M. M. Phillips and C. Contreras, Las Campanas Observatory; and E. Y. Hsiao, Aarhus University, report on the spectroscopic classification of PSN J11104841-3727022 = SN 2014dw using a near-infrared spectrogram (range 800-2500 nm) obtained on 2014 Dec. 14.30 UT with the FoldedPort Infrared Echellette (FIRE) spectrograph on the 6.5-m Magellan Baade Telescope at Las Campanas. The spectrum shows that 2014dw is a type-II supernova, approximately two months past explosion. The near- infrared spectrum is similar to that of SN 2013hj at approximately 60 days past explosion, with several hydrogen Paschen P-Cyg lines. The supernova redshift approximately matches the redshift of the presumed host galaxy (NGC 3568) at z = 0.00815 (Lauberts 1989, The Surface Photometry Catalogue of the ESO-Uppsala Galaxies; via NED).
Central Bureau Electronic Telegrams
- Pub Date:
- January 2015