金彰伟 XM46ZJ = SN2013fw * 超新星 Ia

POSSIBLE SUPERNOVA IN NGC 7042
Zhangwei Jin(Ningbo, Zhejiang, China) and Xing Gao (Urumqi, Xinjiang, China), report the discovery of a possible supernova (mag approximately 17.1) on tow 40-s survey images (limiting mag about 19.0)taken by Xing Gao in Xingming ObservationSky Survey(C42) around Oct .22.6303 and Oct.21.6928 UT,2013. using an unfiltered CCD ( + Celestron C14 Schmidt-Cassegrain telescope D=350-mm @f/6.9 ).the new object approximately located at R.A. =21h 13m 44s.81 Decl.=+13o 4’33”.5(equinox 2000.0). Which is about 11.2″ west and 3.5″ north of the center of the NGC7042.
Nothing is visible at this position on archival images taken on Oct.19,2013. (limiting mag 19.2) or on the DSS(POSS2/UKSTU Red) from Aug. 14,1991(limiting mag about 19.8)
NET USNO-A2.0
XM46ZJ C2013 10 22.63031 21 13 44.81 +13 34 33.5 17.1 V C42
All images can be seen from: http://www.xjltp.com/XOSS/XM46ZJ/XM46ZJ.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.
Electronic Telegram No. 3681
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network

SUPERNOVA 2013fw IN NGC 7042 = PSN J21134481+1334335
Zhangwei Jin, Ningbo, Zhejiang, China; and Xing Gao, Urumqi, Xinjiang,
China, report the discovery of an apparent supernova (mag approximately 17.1)
on two 40-s unfiltered CCD survey images (limiting mag about 19.0) taken by
Gao in the course of the Xingming Sky Survey around Oct. 21.693 and 22.630 UT
using a 35-cm f/6.9 Celestron C14 Schmidt-Cassegrain telescope at Mt. Nanshan.
The new object is approximately located at R.A. = 21h13m44s.81, Decl. =
+13d34’33”.5 (equinox 2000.0), which is about 11″.2 west and 3″.5 north of the
center of NGC 7042.  Nothing is visible at this position on a Digitized Sky
Survey image from 1991 Aug. 14 (limiting red mag about 19.8).  The variable
was designated PSN J21134481+1334335 when it was posted at the Central
Bureau’s TOCP webpage and is here designated SN 2013fw based on the
spectroscopic confirmation reported below.  Additional CCD magnitudes for
2013fw:  2013 Oct. 19, [19.2 (Jin and Gao); 23.244, 16.2 (R. A. Koff, Bennett,
CO, USA; Meade 0.25-m f/10 reflector + Apogee U-47 camera; limiting mag 18.3;
position end figures 44s.77, 33″.1; UCAC3 reference stars; image posted at URL
http://antelopehillsobservatory.org/SNpictures/PSNJ21134481+1334335final.jpg);
23.711, 16.5 (Gianluca Masi, Francesca Nocentini, and Patrick Schmeer,
remotely using a 43-cm telescope at Ceccano, Italy; position end figures
44s.78, 33″.1); 23.743, 16.6 (N. James, Chelmsford, Es***, England; Celestron
C11 reflector; position end figures 44s.77, 33″.3; image posted at website URL
http://nickdjames.com/supernovae/2013/PSNJ21134481+1334335_20131023_ndj.jpg);
25.767, 16.2 (Masi et al.); 24.080, 16.6 (J. Brimacombe, Cairns, Australia;
remotely with a 51-cm telescope located at the New Mexico Skies observatory
near Mayhill, NM, U.S.A.; position end figures 44s.76, 33″.6; image posted at
website URL http://www.flickr.com/photos/43846774@N02/10485931233/).  Masi et
al. add that several low-resolution spectrograms of 2013fw were obtained on
Oct. 25.74 remotely using a 36-cm telescope (+ 100 lines/mm grating, with a
dispersion of 3.47 nm/pixel) at Ceccano, which show a clear Si II absorption
around 615.0 nm, suggesting that 2013fw is a type-Ia supernova.

D. A. Howell, Las Cumbres Observatory Global Telescope (LCOGT) and
University of California at Santa Barbara (UCSB); D. Sand, Texas Tech
University; and S. Valenti and I. Arcavi, LCOGT and UCSB, report that a
spectrogram (wavelength range 320-1000 nm) of PSN J21134481+1334335 = SN
2013fw was obtained with the “Faulkes Telescope North” (+ FLOYDS) on Oct.
24.27 UT.  The spectrum reveals 2013fw to be a type-Ia supernova with high-
velocity features, observed well before maximum light.  Adopting a redshift
of z = 0.01695 for the host galaxy (NGC 7042), the Si 615.0-nm feature
has a minimum at 18000 km/s, while the Ca infrared triplet has a minimum of
approximately 28000 km/s.  Using Superfit (Howell et al. 2005, Ap.J. 634,
1190), best fits are obtained to type-Ia supernovae at approximately two
weeks before maximum light.

NOTE: These ‘Central Bureau Electronic Telegrams’ are sometimes
superseded by text appearing later in the printed IAU Circulars.

(C) Copyright 2013 CBAT
2013 October 30                  (CBET 3681)              Daniel W. E. Green

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