Astronomische Nachrichten, 4 July 2014 Asiago Supernova classification program: blowing out the first two hun- dred candles L. Tomasella1;?, S. Benetti1, E. Cappellaro1, A. Pastorello1, M. Turatto1, R. Barbon1, N. Elias-Rosa1, A. Harutyunyan2, P. Ochner1, L. Tartaglia1, and S.Valenti3;4 1INAF, Osservatorio Astronomico di Padova, 35122 Padova, Italy 2Fundacion´ Galileo Galilei, INAF Telescopio Nazionale Galileo, Rambla Jose´ Ana Fernandez´ Perez´ 7, 38712 Brena˜ Baja, TF, Spain 3Department of Physics, University of California, Santa Barbara, Broida Hall, Mail Code 9530, Santa Barbara, CA 93106- 9530, USA 4Las Cumbres Observatory Global Telescope Network, 6740 Cortona Dr., Suite 102, Goleta, CA 93117, USA The dates of receipt and acceptance should be inserted later Key words supernovae: general – surveys We present the compilation of the first 221 supernovae classified during the Asiago Classification Program (ACP). The details of transients classification and the preliminarily reduced spectra, in fits format, are immediately posted on the Padova-Asiago SN group web site. The achieved performances for the first 2 years of the ACP are analysed, showing that half of all our classifications were made within 5 days from transient detection. The distribution of the supernova types of this sample resembles the distribution of the general list of all the supernovae listed in the Asiago SN catalog (ASNC8, Barbon et al. 1999). Finally, we use our sub-sample of 78 core-collapse supernovae, for which we retrieve the host-galaxy morphology and r-band absolute magnitudes, to study the observed subtype distribution in dwarf compared to giant galaxies. This ongoing program will give its contribution to the classification of the large number of transients that will be soon delivered by the Gaia mission. Copyright line will be provided by the publisher 1 Introduction overview of the recent literature. As examples of the latest advances in SN researches, we recall the discovery of the The surveillance of the transient sky has greatly improved in class of super-luminous supernovae (SNe) whose explosion the last ten years with the contribution of a growing number mechanism is still debated (Pastorello et al. 2010, Quimby of surveys. Panoramic surveys of the nearby Universe like et al. 2011, Gal-Yam 2012) and the real-time observations the Catalina Real-Time transient Survey (CRTS)1, the Palo- of the convulsions of massive stars on their path to explo- mar Transient Factory (PTF)2, the La Silla Quest3, the Mo- sion (Smith et al. 2013, Pastorello et al. 2013, Fraser et al. bile Astronomical System of theTElescope-Robots (MAS- 2013, Margutti et al. 2014). TER)4, the Optical Gravitational Lensing Experiment The classification and early follow-up of bright nearby (OGLE)5, etc, have boosted the number of supernova (SN) SNe can be efficiently done with small/medium size tele- discoveries from ∼ 200 in 2000 to ∼ 1000 in 2013. Many scopes. In the past few years we conducted an European of these surveys post their discoveries in real time, allowing Southern Observatory (ESO) Large Program on Supernova for a change of approach in SN science: for a specific SN Variety and Nucleosynthesis Yields (2009-2012) with the arXiv:1403.7233v3 [astro-ph.HE] 3 Jul 2014 science case the relevant events can be selected and studied. ESO-NTT (New Technology Telescope), complemented However, to really exploit the transient search efforts, with the INAF-TNG (Telescopio Nazionale Galileo of Isti- we need to be able to identify, as early as possible, the event tuto Nazionale di Astrofisica) for the Northern hemisphere, class with a prompt spectroscopic classification. Knowing for the study of selected SNe (eg. Taubenberger et al. 2011, the SN type and phase, one can activate a proper follow up Patat et al. 2011, Fraser et al. 2011, Valenti et al. 2011a, campaign. The observing chain made of wide field searches, Pastorello et al. 2012, Kankare et al. 2012, Pastorello et al. prompt classification and selective follow-ups has proved to 2013, Tomasella et al. 2013a). Building on this successful be extremely productive as can be gathered from an experience, the ESO Large Program was merged into a new major international collaboration, the Public ESO Spectro- 6 ? Corresponding author: e-mail: [email protected] scopic Survey of Transient Objects (PESSTO) , that is us- 1 http://crts.caltech.edu ing a major fraction of the time at the ESO NTT at La Silla 2 http://ptf.caltech.edu/iptf/ (Chile). PESSTO started in 2012 and will be active for 4 3 http://hep.yale.edu/lasillaquest (+1) years (Smartt et al. 2013). 4 http://observ.pereplet.ru 5 http://ogle.astrouw.edu.pl 6 http://www.pessto.org/pessto/index.py Copyright line will be provided by the publisher 2 L. Tomasella: Asiago SN classification Program Despite the efforts of this large project and those of other 30 groups worldwide, a large fraction of transients are not spec- 25 troscopically classified (around 50%, based on the list of 7 Latest Supernovae ). In this context, we decided to give a 20 contribution to the classification of the brightest targets of the Northern hemisphere by exploiting our access at the ob- 15 2012-2013 1985-2008 serving facilities in Asiago, in particular the 1.82m Coper- 10 nico telescope at Cima Ekar, operated by INAF Astronom- ical Observatory of Padova (OAPd). A parallel project is 5 the photometric and spectroscopic follow-up of the most in- 0 teresting transients (classified or not by us), which is not Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec addressed in this paper. In fact, in the last few years the observations in Asiago have been deeply reorganised and Fig. 1 Statistics of the open-dome nights at the Copernico a remarkable amount of telescope-time is allocated for two 1.82m telescope (including the partially used nights) as a or three Large Programs. Our ongoing Classification and function of the month for the past two years (2012−2013) follow-up of extragalactic transients discovered by and comparison with the statistic over the past 24 years panoramic surveys is one of those Large Programs. (1985-2008). June and July are mainly used for telescope and dome maintenance, tests and outreach activities. The Asiago SN Classification Program (ACP) started in 2011, with the aim to classify all transients that are ac- cessible from our latitude and are bright enough for 1.82m during the past ten years (S. Ortolani, private communica- Copernico telescope (apparent magnitude ≤ 19 mag). The tion). project is the latest evolution of Asiago SN programs, which The ACP program proceeds as follows. Suitable targets begun in the early sixties. Among the historical achieve- are identified among those posted by SNe searches. Soon af- ments, we recall: the systematic SN search with Schmidt ter acquisition, the spectra are immediately reduced through telescopes (Rosino 1964); the first identification of peculiar a semi-automatic data reduction pipeline (Sect. 2). The spec- type I SNe (Bertola 1964), named Ib or Ic twenty years later tra are then compared to SN templates aided by automatic (Gaskell et al. 1986); the derivation of an average light curve SN classification codes (Sect. 3.) and the classifications are for type Ia (Barbon et al. 1973) and of the (different) pho- disseminated via the IAU Central Bureau Astronomical Tele- tometric properties of type II (Barbon et al. 1979) SNe; and grams circulars (CBET)9 and/or the Astronomical Telegram the compilation of the Asiago SN Catalogue (Barbon et al. (ATEL)10. Some statistics of the program performances and 1999), intended as a large database for statistical studies on the properties of the classified SN sample are reported in the SN phenomenon (ASNC)8. Sect. 4. The ACP is allocated on average one week of observing Following what we believe is a very fruitful trend of nights per month at the Copernico 1.82m telescope. Typ- many new projects, we made the results of our effort imme- ically half of the allocated time is used for classification diately public: within a few hours from observation, the de- of new targets and half to contribute to follow-up observa- tails of transient classification and the (fast-)reduced spectra tions of selected objects. When the Copernico telescope is (fits format) are posted in the Padova-Asiago SN group web not available, the 1.22m Galileo telescope is used for tran- site 11. sients brighter than magnitude 17. Both these telescopes are located in the Asiago Plateau, North-East of Italy, about 2 Transient selection, observation and data one hundred km from Padova, at an altitude of 1.366 m for Copernico (Mt. Ekar, 11◦ 340 08:42 E, +45◦ 500 54:5200 N) reduction and 1.045 m for Galileo (11◦ 310 300 E, +45◦ 510 5900 N). This site is characterised by a continental climate, with dry We select the SN candidates mainly from the IAU CBAT 12 winters and rainy spring and autumn. Summer time is on av- Transient Object Confirmation Page and from the Astron- 7 erage favourable for observations. A statistics of the nights omy Section of the Rochester Academy of Sciences . In per month with open dome for the last years is plotted in some cases, candidates are notified directly to us by SN Figure 1. The seeing is quite variable during the year, with hunters, who often are amateur astronomers, e.g. the Ital- 13 an average ∼ 200, but nights with seeing around 100 are fre- ian Supernovae Search Program (ISSP) . quently registered. Despite the proximity of large cities, the We prioritize the transients for classification based on collaboration with Asiago Plateau Municipalities and the the following criteria: Regional Agency for the environmental preserve (ARPAV) 9 http://www.cbat.eps.harvard.edu/cbet/RecentCBETs.html has contributed to the decreasing of the local light pollution 10 http://www.astronomerstelegram.org 11 http://sngroup.oapd.inaf.it/ 7 http://www.rochesterastronomy.org/snimages/ 12 http://www.cbat.eps.harvard.edu/unconf/tocp.html 8 http://sngroup.oapd.inaf.it/asnc.html 13 http://italiansupernovae.org/ Copyright line will be provided by the publisher AN header will be provided by the publisher 3 Table 1 Number of classified SNe (central column) Chivens long-slit spectrograph.