Publications of the Astronomical Society of Australia (PASA), Vol. 33, e055, 29 pages (2016). © Astronomical Society of Australia 2016; published by Cambridge University Press. doi:10.1017/pasa.2016.47 The ANU WiFeS SuperNovA Programme (AWSNAP) Michael J. Childress1,2,3,12, Brad E. Tucker1,2, Fang Yuan1,2, Richard Scalzo1, Ashley Ruiter1,2, Ivo Seitenzahl1,2, Bonnie Zhang1, Brian Schmidt1, Borja Anguiano4, Suryashree Aniyan1, Daniel D. R. Bayliss1,5, Joao Bento1, Michael Bessell1, Fuyan Bian1, Rebecca Davies1, Michael Dopita1, Lisa Fogarty6, Amelia Fraser-McKelvie7,8, Ken Freeman1, Rajika Kuruwita1, Anne M. Medling1, Simon J. Murphy1,SimonJ.Murphy6,9, Matthew Owers4,10, Fiona Panther1,2, Sarah M. Sweet1, Adam D. Thomas1 and George Zhou11,1 1Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611, Australia 2ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), Canberra, ACT, Australia 3School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, UK 4Department of Physics and Astronomy, Macquarie University, NSW 2109, Australia 5Observatoire Astronomique de l’Université de Genève, 51 ch. des Maillettes, 1290 Versoix, Switzerland 6Sydney Institute for Astronomy (SIfA), School of Physics, The University of Sydney, NSW 2006, Australia 7School of Physics and Astronomy, Monash University, Clayton, Victoria 3800, Australia 8Monash Centre for Astrophysics (MoCA), Monash University, Clayton, Victoria 3800, Australia 9Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark 10Australian Astronomical Observatory, PO Box 915, North Ryde, NSW 1670, Australia 11Harvard-Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA 02138, USA 12Email: [email protected] (RECEIVED July 11, 2016; ACCEPTED October 5, 2016) Abstract This paper presents the first major data release and survey description for the ANU WiFeS SuperNovA Programme. ANU WiFeS SuperNovA Programme is an ongoing supernova spectroscopy campaign utilising the Wide Field Spectrograph on the Australian National University 2.3-m telescope. The first and primary data release of this programme (AWSNAP-DR1) releases 357 spectra of 175 unique objects collected over 82 equivalent full nights of observing from 2012 July to 2015 August. These spectra have been made publicly available via the WISEREP supernova spectroscopy repository. We analyse the ANU WiFeS SuperNovA Programme sample of Type Ia supernova spectra, including measurements of narrow sodium absorption features afforded by the high spectral resolution of the Wide Field Spectrograph instrument. In some cases, we were able to use the integral-field nature of the Wide Field Spectrograph instrument to measure the rotation velocity of the SN host galaxy near the SN location in order to obtain precision sodium absorption velocities. We also present an extensive time series of SN 2012dn, including a near-nebular spectrum which both confirms its ‘super-Chandrasekhar’ status and enables measurement of the sub-solar host metallicity at the SN site. Keywords: supernovae: general – supernovae: individual: (SN 2012dn) 1 INTRODUCTION ously, these surveys have discovered hundreds of supernovae (SNe) of ‘traditional’ types (see Filippenko 1997, for a re- In the last decade, wide-field extragalactic transient view), enabling statistical analyses of the properties of these surveys—such as the Palomar Transient Factory (PTF; SNe. Rau et al. 2009; Law et al. 2009), the Panoramic Sur- Whilst imaging surveys have provided discovery and light vey Telescope and Rapid Response System (PanSTARRS; curves for this wealth of new transients, complementary spec- Kaiser et al. 2010), the Catalina Real-time Transient Sur- troscopy surveys have provided the critical insight into the vey (CRTS; Drake et al. 2009), the Texas Supernova Search physical origins of these events. Numerous supernova spec- (Quimby 2006; Yuan 2010), and the All-Sky Automated troscopy surveys have released thousands of high-quality Survey for Supernovae (ASAS-SN; Shappee et al. 2014; spectra of nearby SNe into the public domain (Matheson Holoien et al. 2016)—have revolutionised our understand- et al. 2008; Blondin et al. 2012; Silverman et al. 2012c;Fo- ing of the myriad ways in which stars explode through the latelli et al. 2013; Modjaz et al. 2014). These surveys have discovery of new classes of exotic transients. Simultane- frequently been dedicated to the spectroscopic follow-up of 1 Downloaded from https://www.cambridge.org/core. University of Sydney Library, on 09 Oct 2017 at 03:35:34, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/pasa.2016.47 2 Childress et al. Type Ia supernovae (SNe Ia) which, due to their rates and lu- Table 1. Details of WiFeS gratings. minosities, dominate any magnitude-limited imaging survey. λ λ Such surveys have revealed that photometrically similar SNe Grating min max Pixel size Resolution can still exhibit diversity of spectroscopic behaviour, indicat- B3000 3 500 A˚ 5 700 A0.77˚ A1.5˚ A˚ ing spectra remain a critical tool for revealing the full nature R3000 5 400 A˚ 9 570 A1.25˚ A2.5˚ A˚ of the supernova progenitors (particularly for SNe Ia). Addi- R7000 5 400 A˚ 7 020 A0.44˚ A0.9˚ A˚ tionally, spectra remain critical for supernova classification— particularly at early phases when the full photometric evolu- tion has yet to be revealed. Such early classifications then inform the use of additional SN follow-up facilities, includ- 2 OBSERVATIONS AND DATA DESCRIPTION ing those operating outside the optical window. Recently, the Public ESO Spectroscopic Survey for Tran- Observations for AWSNAP were conducted with the sient Objects (PESSTO; Smartt et al. 2015) began a multi- WiFeS—(Dopita et al. 2007, 2010) on the ANU 2.3-m tele- year programme on the NTT 3.6-m telescope in Chile, with scope at Siding Spring Observatory in northern New South the goal of obtaining high-quality spectral time series for Wales, Australia. Observing nights were classically sched- roughly 100 transients (of all kinds) to be released to the uled with a single night of observing every 8–15 d. On some public. This survey has already released hundreds of spectra occasions, special objects of interest were observed during in its first two annual data releases, and continues to release all non-AWSNAP nights. A full list of the AWSNAP transient SN classification spectra within typically1dfromobserva- spectra is presented in Table A3 in Appendix A. In the sec- tion. Other ongoing SN spectroscopy programmes, such as tions that follow, we describe the processing of the WiFeS the Asiago Supernova Programme (Tomasella et al. 2014), data, then characterise both the long-term performance of the also make important contributions to the transient com- WiFeS instrument and observing conditions at Siding Spring. munity through timely SN classification and spectroscopy releases. 2.1. Data reduction and supernova spectrum Here, we describe our ongoing spectroscopy programme extraction AWSNAP—the ANU WiFeS SuperNovAProgramme— which uses the Wide Field Spectrograph (WiFeS; Dopita et al. The WiFeS instrument is an image-slicing integral field spec- 2007, 2010) on the Australian National University (ANU) trograph with a wide 25 arcsec × 38 arcsec field of view. 2.3-m telescope at Siding Spring Observatory in Australia. For AWSNAP, this frequently provided simultaneous inte- In this paper, we describe the data processing procedures for gral field observations of SNe and their host galaxies. The this ongoing programme, and describe the first AWSNAP WiFeS image slicer breaks the field of view into 25 ‘slitlets’ data release (AWSNAP DR1) comprising 357 spectra of 175 of width 1 arcsec, which then pass through a dichroic beam- supernova of various types obtained during 82 classically splitter and volume phase holographic (VPH) gratings before scheduled observing nights over a 3-yr period from 2012 arriving at 4k × 4k CCD detectors. AWSNAP observations July to 2015 August. Most of these spectra have been re- were always conducted with a CCD binning of 2 in the ver- leased publicly via the Weizmann Interactive Supernova data tical direction—this sets the vertical spatial scale of the de- REPository (WISeREP1— Yaron & Gal-Yam 2012), with the tector to be 1 arcsec, yielding final integral field elements (or remainder set to be released within the next year as part of ‘spaxels’) of size 1 arcsec × 1 arcsec. Typically seeing at forthcoming PESSTO papers. This programme will continue Siding Spring is roughly 2 arcsec (see Section 2.3). to observe SNe of interest and classify SN discoveries from The VPH gratings utilised by WiFeS provide a higher transient searches such as the new SkyMapper Transients wavelength resolution than traditional glass gratings. The Survey (Keller et al. 2007). We aim to release future SN clas- low- and high-resolution gratings provide resolutions of R = sification spectra from AWSNAP publicly via WISeREP in 3 000 and R = 7 000, respectively, yielding velocity resolu- −1 parallel with any classification announcements. tions of up to σv ∼ 45 km s which is ideal for observ- This paper is organised as follows. Section 2 describes the ing nebular emission lines from ionised regions in galax- WiFeS data processing and SN spectrum extraction proce- ies. For SNe, this can reveal narrow absorption features (see dures. Section 3 presents general properties of our SN sam- Section 4.2) from circumstellar material (CSM) which are ple and compares AWSNAP DR1 to other public SN spectra typically smeared out by lower resolution spectrographs. releases. In Section 4, we present some analysis of the prop- AWSNAP observations were generally conducted with the erties of the SNe Ia in our sample, including measurement of lower resolution B3000 and R3000 gratings for the blue and narrow sodium absorption features afforded by the interme- red arms of the spectrograph, respectively, with the RT560 diate resolution of the WiFeS spectrograph. Some concluding dichroic beamsplitter. Occasionally, the R7000 grating was remarks follow in Section 5.