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Special Notice #269: SUPERNOVA 2012aw IN M95 (NGC 3351) = PSN J10435372+1140177

March 24, 2012:  Most of the information in this Special Notice was announced in IAU CBAT CBET 3054 (Daniel W. E. Green, Ed.). Three independent discoveries of SN 2012aw in M95 are reported:

 - Jure Skvarc (Crni Vrh Observatory, Slovenia), magnitude R = 13, 2012 March 17.90 UT, (0.60-m f/3.3 Cichocki telescope; independent discovery on four 60-s images; image posted at URL http://www.observatorij.org/vstars/PSN20120317/PSNJ10435372+1140177.jpg. Nothing was visible in seven archive images taken 2005 Apr. 25-2012 Feb. 15. The variable is only 3.3" from an x-ray source noted by Swartz et al. (2006, Ap.J. 647, 1030; object s8);

 - Alessandro Dimai (Cortina d'Ampezzo, Italy), magnitude 15.4, 2012 March 16.849 UT, independent discovery in the course of the Italian Supernovae Search Project; image posted at URL http://www.cortinastelle.it/M95_20120316_202322_20_Luminance_2_Maioni.jpg);

 - Paolo Fagotti (Bastia Umbra, Italy), magnitude R = 15, 2012 March 16.86 UT with a 0.5-m reflector (+ MX916 camera) at Porziano d'Assisi, Italy; first discovery of SN 2012aw reported to CBAT

Coordinates (2000.0): R.A. = 10 43 53.76, Decl. = +11 40 17.9 (Fagotti);
position end figures 53.78s, 17.0" (Dimai);
53.72s, 17.7", offset 60" west, 115" south of the center of M95 (Skvarc)
53.73s, 17.8" (Gianluca Masi, Ceccano, Italy)

The name PSN J10435372+1140177 was assigned when Skvarc posted his discovery at the Central Bureau's TOCP webpage.

Initial, underexposed spectra obtained by Ulisse Munari, Istituto Nazionale di Astrofisica, Padova Astronomical Observatory, on March 17.77 UT with the Asiago Observatory 1.22-m reflector (+ Boller & Chivens spectrograph) showed a very blue continuum, essentially featureless, with no absorption bands and no detectable emission lines, similar to a cataclysmic variable.

Evolution of the spectrum to confirm the object as a very young type-II supernova discovered a few days after core collapse was seen in spectra obtained 1) by R. Itoh, T. Ui, and Masayuki Yamanaka, Hiroshima University, on 2012 March 19.5 UT at the Higashi-Hiroshima Observatory, Hiroshima University, and 2) by A. Siviero, L. Tomasella, A. Pastorello, S. Benetti, and U. Munari, Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova, M. Ergon, J. Sollerman, and F. Taddia, Department of Astronomy, Stockholm University, and G. Barisevicius, Nordic Optical Telescope, on 2012 March 19.85 UT with the 1.22-m Galileo telescope (+ Boller & Chivens spectrograph) and on 2012 March 19.92 UT with the 2.5-m Nordic Optical Telescope (+ ALFOSC).

Observations reported to the AAVSO include:
2012 March 13.96 UT, <19.5 (A. Dimai, Cortina d'Ampezzo, Italy, via CBET 3054);
14.89, <17.3 V (U. Quadri, L.Strabla, R. Girelli, and A. Quadri, 25-cm f/5 robotic telescope, Bassano Bresciano, Italy, via CBET 3054);
15.8100, <16.1 (J. Piriti, Szepetnek, Hungary);
17.04, 13-14 (Luigi Fiorentino, Bari, Italy, possible independent detection, via CBET 3054);
17.94, 13.71 B (A. Vagnozzi and F. Castellani, ANS Collaboration, via CBET 3054);
17.94, 13.81 V (Vagnozzi and Castellani, via CBET 3054);
18.85, 13.58 B (Vagnozzi and Castellani, via CBET 3054);
18.85, 13.63 V (Vagnozzi and Castellani, via CBET 3054);
18.8830, 13.6 (Piriti);    
19.0109, 13.70 V +/-0.04 (S. Howerton, Arkansas City, KS);
19.8264, 13.4 (D. Vansteelant, Varsenare, Belgium);
19.8611, 13.3 (A. Sucker, Hildesheim, Germany);
19.8770, 13.3 (Piriti);
19.8819, 13.2 (Sucker);
19.985, 13.3 (G. Masi, 43-cm f/6.8 robotic telescope, Ceccano, Italy, via CBET 3054);
20.0013, 13.520 V +/-0.008 (D. Boyd, West Challow, Wantage, England);
20.0020, 13.369 R +/-0.010 (Boyd);
20.0264, 13.2 (B. Billiaert, Duffel, Belgium);
20.8063, 13.3 (W. Kriebel, Schierling/Walkenstetten, Germany);
20.9280, 13.2 (G. Poyner, Birmingham, England);
21.0444, 13.2 (R. Tyson, Freeport, NY);
21.0650, 13.665 B +/-0.016 (C. Littlefield, Loudonville, NY);
21.0718, 13.340 V +/-0.008 (Littlefield);
21.1379, 13.36 V +/-0.04 (H. Smith, East Lansing, MI);
21.1404, 13.371 V +/-0.064 (P. Temple, Deming, NM);
21.8181, 13.2 (Kriebel);
21.8194, 13.1 (K. Wenzel, Grossostheim, Germany);
21.8507, 13.1 (Sucker);
21.8861, 13.2 (J. Banks, Havelock, NC);
21.8938, 13.27 V+/-0.05 (S. Teichner, Budapest, Hungary);
21.8938, 13.3 (Teichner);
21.9147, 13.419 V +/-0.025 (M. Martignoni, Magnago, Italy);
21.9243, 13.357 V +/-0.01 (A. Sonka, Bucharest, Romania);
21.9333, 13.3 (Billiaert);
21.9696, 13.386 V +/-0.017 (Boyd);
21.9703, 13.228 R +/-0.021 (Boyd);
22.0363, 13.37 V +/-0.02 (Smith);
22.0385, 13.48 B +/-0.03 (Smith);
22.0411, 13.19 I +/-0.03 (Smith);
22.1139, 13.4 (S. Tracy, NOrth Granby, CT);
22.2610, 13.343 V +/-0.008 (J. Davis, Crofton, MD);
22.2700, 13.109 R +/-0.010 (Davis);
22.2790, 13.049 I +/-0.015 (Davis);
22.2923, 13.470 B +/-0.008 (Davis);
22.8243, 13.1 (Kriebel);
22.8630, 13.346 V +/-0.032 (Boyd);
22.8632, 13.1 (Billiaert);
22.8637, 13.192 R +/-0.026 (Boyd);
22.9479, 13.2 (Jose Ripero Osorio, Madrid, Spain);
23.0799, 13.0 (R. Fuller, Huntsville, TX);
23.2318, 13.255 V +/-0.114 (Temple);
23.8500, 13.33 CV +/-0.03 (A. Popowicz, Gliwice, Poland);
23.8611, 13.2 (Sucker);    
23.8715, 13.1 (Wenzel);

Finder charts for SN 2012aw may be plotted using the AAVSO International Variable Star Plotter (VSP) at Http://www.aavso.org/vsp.

Please report observations to the AAVSO International Database as SN 2012aw.

This AAVSO Special Notice was compiled by Elizabeth O. Waagen.

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