4月27日晨，金彰伟在查看凌晨拍摄的SN图片（NGC3972）中发现一颗超亮超新星，测量星等14.2等左右，及时上报。2小时后，日本爱好者利用美国远程天文台验证。
POSSIBLE SUPERNOVA IN NGC 3972
Zhangwei Jin(Ningbo, Zhejiang, China) and Xing Gao (Urumqi, Xinjiang, China), report the discovery of a possible supernova (mag approximately 14.2) on a 60-s survey image (limiting mag about 19.5)taken by Xing Gao in Xingming ObservationSky Survey(C42) around Apr. 26.82344 UT,2011. using a unfilled CCD ( + Celestron C14 Schmidt-Cassegrain telescope D=350-mm @f/6.9 ).the new object approximately located at R.A. =11h 55m 45s.56 Decl.=+55°19’33”.8 (equinox 2000.0). Which is about 5.3″ east and 19.1″ north of the center of the galaxy NGC 3972.
Nothing is visible at this position on archival images taken on Apr. 10 (limiting mag 19.5) and Apr. 08 (limiting mag 19.5) or on the DSS from May 07,1991(limiting mag about 19.5).
NET USNO-A2.0
XM20ZJ C2011 04 26.82344 11 55 45.56 +55 19 33.8 14.2 R C42
All images can be seen from: http://www.xjltp.com/XOSS/XM20ZJ/XM20ZJ.htm
C42 Xingming Observatory, Mt. Nanshan. Observers Z.Jin, X.Gao ,Measurers Z.Jin 0.35-m f/6.9 Schmidt-Cassegrain telescope and CCD.
SUPERNOVA 2011by IN NGC 3972 = PSN J11554556+5519338
Zhangwei Jin, Ningbo, Zhejiang, China; and Xing Gao, Urumqi, Xinjiang,
China, report the discovery of a possible supernova (mag approximately 14.2)
on a 60-s survey image (limiting mag about 19.5) taken by Xing Gao in the
course of the Xingming Observation Sky Survey around Apr. 26.8234 UT using a
Celestron C14 Schmidt-Cassegrain telescope (+ unfiltered CCD camera) at Mt.
Nanshan. The new object is approximately located at R.A. = 11h55m45s.56,
Decl. = +55d19’33”.8 (equinox 2000.0), which is about 5″.3 east and 19″.1
north of the center of the galaxy NGC 3972. Nothing is visible at this
position on archival images taken on Apr. 8 and 10 (limiting mag 19.5) or on
a Digitized Sky Survey image from 1991 May 7 (limiting mag about 19.5; no
plate type or bandpass noted). The discovery image is posted at the
following website URL: http://www.xjltp.com/XOSS/XM20ZJ/XM20ZJ.htm. This
variable was designated PSN J11554556+5519338 when posted at the Central
Bureau’s TOCP webpage and is here designated SN 2011by based on the
spectroscopic report below.
Joseph Brimacombe, Cairns, Australia, reports that he obtained unfiltered
CCD images remotely using a 51-cm RCOS telescope (+ STL11K camera) at the New
Mexico Skies Observatory near Mayhill, New Mexico, on Apr. 27.332 UT, yielding
mag 14.5 and position end figures 45s.57, 33″.9 for 2011by. He has posted his
image at website URL http://www.flickr.com/photos/43846774@N02/5661036373/.
T. Zhang and Z. Zhou, National Astronomical Observatories of China (NAOC);
X. Wang, Tsinghua Center for Astrophysics, Tsinghua University, report on an
optical spectrum (range 350-870 nm) of PSN J11554556+5519338 = SN 2011by that
was obtained on Apr. 27.5 UT with the 2.16-m telescope (+ BFOSC) at the
Xinglong Station of the NAOC. The spectrum is consistent with that of a
type-Ia supernova at very young phase. Cross-correlation with a library of
supernova spectra using the “Supernova Identification” code (SNID; Blondin
and Tonry 2007, Ap.J. 666, 1024) shows that this supernova matches that of SN
2003du at about 10 days before maximum. After removal of the host-galaxy
recession velocity of about 850 km/s, they find the absorption minimum of the
Si II 635.5-nm line to be blueshifted by about 12000 km/s. Further follow-up
observations of this object are encouraged.
NOTE: These ‘Central Bureau Electronic Telegrams’ are sometimes
superseded by text appearing later in the printed IAU Circulars.
(C) Copyright 2011 CBAT
2011 April 28 (CBET 2708) Daniel W. E. Green
AAVSO Alert Notice 438
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!