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Alert Notice 577: SN 2017eaw in NGC 6946 (PSN J20344424+6011359)

Correction: The original announcement of this Alert Notice included the incorrect assignment of observations made by David Boyd to David Blane. The attribution has been corrected in the observations below. We extend sincere apologies to David Boyd for the error. -- EOW  May 17, 2017

May 16, 2017

Event: SN 2017eaw - bright supernova in NGC 6946 (Cepheus)

Discovered by: Patrick Wiggins (Tooele, UT)

Discovery magnitude: unfiltered CCD magnitude ~12.8 (using a 0.35-m f/5.5 reflector near Erda, UT)

Discovery date: 2017 May 14.2383 UT
 
Coordinates (2000.0): R.A. 20 34 44.24  Decl. +60 11 35.9 (from VSX)
The supernova is located 153” NW of the center of NGC 6946.
 
Spectra: Y.-C. Cheng (IANCU) et al. report that spectra obtained on 2017 May 14.7574 UT indicate SN 2017eaw to be an early Type II supernova (ATel #10374). Also, spectra classifying SN 2017eaw as a young Type IIP supernova one week before maximum light were obtained by D. Xiang (Tsinghua University) et al. on 2017 May 14.79 UT (ATel #10376). In addition, L. Tomasella (INAF OAPd) et al. on behalf of the NUTS collaboration report that spectra obtained on May 15.1309 UT confirm the object as a young Type-II supernova (ATel #10377).

Observing recommendations: Observations of all types (visual, CCD, DSLR, spectroscopy) and all bands as instrumentation permits are strongly encouraged as the nova evolves.

Observations reported to the AAVSO:

2017 May 14.2383 UT, 12.8: (unfiltered CCD; WPK, P. Wiggins, Tooele, UT, discovery; via TOCP page);
14.50284, 13.450 B +/-0.020 (FJQ, J. Foster, Los Angeles, CA);
14.50358, 13.423 B +/-0.019 (Foster);
14.50432, 13.445 B +/-0.022 (Foster);
14.50531, 13.143 V +/-0.021 (Foster);
14.50588, 13.102 V +/-0.022 (Foster);
14.50645, 13.150 V +/-0.025 (Foster);
14.50725, 12.753 I +/-0.043 (Foster);
14.50785, 12.680 I +/-0.044 (Foster);
14.50838, 12.680 I +/-0.048 (Foster);
14.88276, 13.189 B +/-0.036 (BDG, D. Boyd, West Challow, UK; selected from 88 BV obs May 14.88276-.94279)
14.88333, 13.124 V +/-0.014 (Boyd);
14.89073, 13.182 B +/-0.026 (Boyd);
14.89130, 13.111 V +/-0.018 (Boyd);
14.90097, 13.149 B +/-0.028 (Boyd);
14.90154, 13.122 V +/-0.014 (Boyd);
14.90837, 12.874 R +/-0.006 (NRNA, R. Nogues Naves, Cabrils, Spain; selected from 34 VRSGSRSI obs May 14.90837-15.13622);
14.91018, 13.111 V +/-0.009 (Boyd);
14.91164, 13.087 V +/-0.007 (MAND, A. Mantero, Bernezza, Italy);
14.91472, 13.092 V +/-0.007 (Nogues Naves);
14.92037, 13.124 V +/-0.010 (Boyd);
14.92702, 12.948 R +/-0.006 (Nogues Naves);
14.93334, 13.146 V +/-0.007 (Nogues Naves);
14.93968, 13.108 SG +/-0.007 (Nogues Naves);
14.94209, 13.106 V +/-0.019 (Boyd);
14.94279, 13.120 V +/-0.018 (Boyd);
14.94598, 13.191 SR +/-0.006 (Nogues Naves);
14.95227, 13.253 SI +/-0.009 (Nogues Naves);
15.08287, 13.123 V +/-0.026 (CIVA, I. Cervini, Leontica, Switzerland);
15.12359, 12.846 R +/-0.006 (Nogues Naves);
15.12990, 13.054 V +/-0.006 (Nogues Naves);
15.13622, 13.015 SG +/-0.006 (Nogues Naves);
15.22431, 13.0 (MCPA, C. Maloney, Helena, AR);
15.34791, 13.028 V +/-0.003 (HBB, B. Harris, New Smyrna Beach, FL);
15.34876, 12.905 B +/-0.006 (Harris);
15.34961, 12.788 R +/-0.021 (Harris);
15.35091, 12.561 I +/-0.012 (Harris);
15.37083, 12.9 (SLH, L. Shotter, Uniontown, PA);
15.89583, 12.76 (MAEA, A. Morozov, Novozybkov, Russian Federation);
15.96515, 12.710 R +/-0.007 (Nogues Naves);
15.97115, 12.951 V +/-0.009 (Nogues Naves);
15.97717, 12.966 SG +/-0.008 (Nogues Naves);
15.98316, 12.953 SR +/-0.009 (Nogues Naves);
15.98916, 12.982 SI +/-0.012 (Nogues Naves);
16.03125, 12.9 (WKL, K. Wenzel, Grossostheim, Germany);
16.07854, 13.001 V +/-0.023 (Cervini);
16.08343, 13.029 V +/-0.025 (Cervini);
16.17081, 12.888 V +/-0.025 (ATE, T. Arranz, Navas De Oro, Spain);
16.17778, 12.8 (Shotter);
16.38194, 12.7 (CCY, C. Chiselbrook, Canton, GA);

Charts: Charts with a comparison star sequence for SN 2017eaw may be created using the AAVSO Variable Star Plotter (VSP). Observers may find it helpful to choose the option to print the DSS image of the galaxy in the chart background.

Submit observations: Please submit observations to the AAVSO International Database using the name SN 2017eaw.

Notes:
a. Designated PSN J20344424+6011359 when posted to the IAU Central Bureau for Astronomical Telegrams Transient Object Confirmation Page (TOCP) at http://www.cbat.eps.harvard.edu/unconf/tocp.html. Wiggins' discovery details are taken from the TOCP page (posted there by P. Schmeer, Saarbruecken-Bischmisheim, Germany). ATel links are (http://www.astronomerstelegram.org/?read=10372) [and 10373, 10374, 10376, 10377, 10378, 10380].

b. Wiggins reports nothing was visible at the supernova's position on his image taken May 12. Optical confirmation was obtained by S. Dong (KIAA-PKU) and K. Stanek (Ohio State) on May 14.4379 UT (ATel #10372).

c. R. Khan (University of Washington) reports probable progenitor candidate present at RA 20:34:44.29, Dec +60:11:36.02 in the catalog of mid-IR sources in nearby galaxies published in Khan 2017 (ApJ S, 228, 5). The cataloged object is at <0.76" from the reported location of the transient (ATel #10373). S. Van Dyk (Caltech/IPAC) et al., using HST ACS/WFC archival data, report the probable progenitor to be a red supergiant located approximately 6.4 WFC pixels (about 0.3 arcsec) to the southwest of the discovery position (ATel #10378).

d. A. Kong (NTHU; Oxford) and K. Li (Michigan State) report that Chandra archival X-ray data (2001-2012) show no X-ray emission correlated with the supernova position; Swift TOO observations from May 14 (two observations ~8 hours apart) show X-ray emission present and increasing (ATel #10380).

e. Xiang et al. (ATel #10376) report SN 2017eaw is the tenth supernova discovered in NGC 6946, to date the most prolific supernova-producing galaxy.

f. Images
- P. Wiggins (Tooele, Utah, 2017 May 14.2383 UT, discovery image): http://users.wirelessbeehive.com/~paw/ngc6946-1.jpg
- M. Mobberley (Suffolk, UK (remotely via iTelescope.NET T24, Auberry, CA), 2017 May 14.4417 UT): http://martinmobberley.co.uk/images/2017eaw_20170514_mpm.jpg

Congratulations to Patrick Wiggins on his discovery!

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

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