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AAVSO Alert Notice 438

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SUPERNOVA 2011by in NGC 3972 = PSN J11554556+5519338

April 28, 2011

Discovered by:  Zhangwei Jin, Ningbo, Zhejiang, China, and Xing Gao, Urumqi, Xinjiang, China

Discovery Date:  Apr. 26.8234 UT

Discovery Magnitude:  approximately 14.2 using a Celestron C14 Schmidt-Cassegrain telescope (+ unfiltered CCD camera) at Mt. Nanshan

Position:  R.A. = 11:55:45.56  Decl. = +55:19:33.8 (equinox 2000.0)
SN 2011by is about 5.3" east and 19.1" north of the center of NGC 3972.

Spectra:  Spectra obtained on 2011 Apr. 27.5 UT with the 2.16-m telescope (+ BFOSC) at the Xinglong Station of the NAOCT by T. Zhang and Z. Zhou, National Astronomical Observatories of China (NAOC), and X. Wang, Tsinghua Center for Astrophysics, Tsinghua University, show SN 2011by to be a type-Ia supernova at a very early phase, about 10 days before maximum.

Charts:  Finder charts for SN 2011by (AUID 000-BKB-410) may be plotted by entering the name or the coordinates above into VSP:  http://www.aavso.org/vsp

Reporting Observations:  Please report all observations to the AAVSO International Database as SN 2011by.

Notes:
a. Initially announced in Central Bureau for Electronic Telegrams 2708 (Daniel W. E. Green, ed.). All information in this Alert Notice comes from CBET 2708.

b. According to Green, the object was designated PSN J11554556+5519338 when posted on the Central Bureau's Transient Objects Confirmation Page (TOCP) webpage, and was designated SN 2011by based on spectroscopic reports.
 
c. Nothing was visible down to magnitude 19.5 at this position on images taken by Zhangwei Jin and Xing Gao on Apr. 8 and 10, or on a Digitized Sky Survey image from 1991 May 7 down to 19.5 (plate type or bandpass not reported).

d. Discovery image by Zhangwei Jin and Xing Gao posted at the following website URL:  http://www.xjltp.com/XOSS/XM20ZJ/XM20ZJ.htm.  

e. Unfiltered CCD images obtained remotely by Joseph Brimacombe, Cairns, Australia, using a 51-cm RCOS telescope (+ STL11K camera) at the New Mexico Skies Observatory near Mayhill, New Mexico, on Apr. 27.332 UT yield magnitude 14.5 and position end figures 45.57s, 33.9"; image posted at website URL http://www.flickr.com/photos/43846774@N02/5661036373/.

Congratulations to Zhangwei Jin and Xing Gao on their discovery!

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