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Alert Notice 487: Supernova 2013dy in NGC 7250 = PSN J22181760+4034096

July 19, 2013

Event: Supernova 2013dy in NGC 7250 (Lacerta) = PSN J22181760+4034096

Independent discovery by:
 - Lick Observatory Supernova Search (LOSS), reported by C. Casper, W. Zheng, W. Li, and A. V. Filippenko (University of California at Berkeley) and S. B. Cenko (Goddard Space Flight Center)
 - Kuniaki Goto (Miyoshi-shi, Hiroshima Prefecture, Japan), communicated by Shoichi Itoh (National Astronomical Observatory of Japan)

Discovery magnitude:
 - LOSS: CCD magnitude 17.0, on unfiltered Katzman Automated Imaging Telescope (KAIT) images
 - Goto: about 16, using 35-cm Schmidt-Cassegrain telescope

Discovery date:
 - LOSS: 2013 July 10.45 UT
 - Goto: 2013 July 11.735 UT

Coordinates: R.A. = 22 18 17.60, Decl.= +40 34 09.6 (2000.0)
SN 2013dy is offset 2.1" west, 24.9" north from the nucleus of NGC 7250 (coordinates and offset from LOSS).

Spectra: SN 2013dy is a Type-Ia supernova discovered one to two weeks before maximum, according to spectra by:
 - D. D. Balam (Dominion Astrophysical Observatory, National Research Council of Canada (NRCC)), M. L. Graham (Las Cumbres Observatory Global Telescope, University of California at San Diego), and E. Y. Hsiao (Las Campanas Observatory) obtained on Jul 13.31 UT with the NRCC 1.82-m Plaskett Telescope;
 - J.-J. Zhang (Yunnan Astronomical Observatory (YNAO)) and X.-F. Wang (Tsinghua University) obtained on Jul 14.75 UT with the 2.4-m telescope (+YFOSC) at YNAO LiJiang Gaomeigu Station;
 - W. Zheng (University of California, Berkeley), S. B. Cenko (Goddard Space Flight Center, NASA), K. I. Clubb, O. D. Fox, P. L. Kelley, and A. V. Filippenko (University of California, Berkeley), and J. M. Silverman (University of Texas) obtained on Jul 11.7 with the 10-m Keck II telescope (+ DEIMOS spectrograph) at Keck Observatory.

Observations reported to the AAVSO:
2013 Jul 8.45 UT, <18.5 U (unfiltered KAIT CCD photometry, via CBET 3588);
10.086, 19.1 (F. Ciabattari, Borgo a Mozzano, Italy, 0.5-m Newtonian telescope + FLI Proline 4710 camera, via CBET 3588);
10.7, 16.6 (A. Mantero, Bernezzo, Italy; 0.25-m f/4 reflector, via CBET 3588);
11.909, 16.0 (G. Masi and F. Nocentini, remotely using 43-cm robotic telescope, Virtual Telescope Project facility in Ceccano, Italy, via CBET 3588);
11.994, 16.3 V (M. Martignoni, Magnago, Italy;0.25-m f/10 Schmidt-Cassegrain reflector, via CBET 3588);
12.423, 15.7 (L. Elenin, Lyubertsy, Russia, and I. Molotov, Moscow, Russia; remotely using 0.45-m f/2.8 telescope at ISON-NM Observatory near Mayhill, NM, via CBET 3588);
14.37, 14.5 U (KAIT, via CBET 3588);
15.96528, 14.5 (K. Wenzel, Grossostheim, Germany, visual);
16.19444, 14.4 (T. C. Hoffelder, Norway, ME, visual);
16.93750, 13.9 (Wenzel, visual);
18.91319, 13.5 (Wenzel, visual);

Charts: Charts for SN 2013dy may be created using the AAVSO Variable Star Plotter (VSP) at

Submit observations: Please submit observations to the AAVSO International Database using the name SN 2013dy.

a. Announced on IAU CBAT Central Bureau Electronic Telegram 3588 (Daniel W. E. Green, ed.). Except for observations reported to the AAVSO and Note e, all information in this Alert Notice comes from CBET 3588.

b. SN 2013dy was designated PSN J22181760+4034096 when it was posted on the CBAT TOCP webpage ( Note that the offset was incorrectly posted on the TOCP page as 24.9" south.
c. Position end figures and additional observation details for all observations reported here via CBET 3588 are available in CBET 3588.

d. SN 2013dy images:
 - F. Ciabattari (Jul 10.086, 19.1), at
 - Andrea Mantero (Jul 10.7, 16.6), at
 - L. Elenin and I. Molotov (Jul 12.423, 15.7), at

e. J. Ryan (Harvard-Smithsonian Center for Astrophysics) reports in ATel #5216 ( that he and colleagues will be taking HST UV spectra of SN 2103dy 10 times over the next month, beginning 2013 July 21 ~11:00 UT. He requests observations at all wavelengths.

Congratulations to the LOSS team and to Kuniaki Goto on their independent discoveries!

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


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