[IAUC] CBET 2969: 20120107 : SUPERNOVA 2011js IN NGC 1103 = PSN J02480496-1357511

Sab Ene 7 02:10:04 ART 2012

                                                  Electronic Telegram No. 2969
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 en eps.harvard.edu (alternate cbat en iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


SUPERNOVA 2011js IN NGC 1103 = PSN J02480496-1357511
     S. Howerton, Arkansas City, KS, U.S.A.; A. J. Drake, S. G. Djorgovski,
A. Mahabal, M. J. Graham, and R. Williams, California Institute of Technology;
J. L. Prieto, Princeton University; M. Catelan, Pontificia Universidad Catolica
de Chile; R. H. McNaught and G. Garradd, Australian National University; E. C.
Beshore and S. M. Larson, Lunar and Planetary Laboratory, University of
Arizona; and E. Christensen, Gemini Observatory, report the discovery of an
apparent supernova in public images from the Catalina Sky Survey (CSS).

 SN       2011 UT       R.A. (2000.0) Decl.      Mag.      Offset
 2011js   Dec. 31.16   2 48 04.96  -13 57 51.1   17.7    15".2 W, 17".9 S

The variable was designated PSN J02480496-1357511 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2011js based on the
spectroscopic confirmation reported below.  After posting on the TOCP,
the following independent discovery report was received.
     J. Maza, M. Hamuy, R. Antezana, L. Gonzalez, R. Cartier, F. Forster, S.
Silva, F. Carrasco, P. Sanchez, C. Hervias, and R. Ramirez, Universidad de
Chile; G. Pignata, M. Cifuentes, Y. Apostolovski, and M. Vidal, Universidad
Andres Bello; C. Farias and F. Aros, Pontificia Universidad Catolica de Chile;
B. Conuel, Wesleyan University; G. Folatelli, IPMU, University of Tokyo; and
D. Reichart, K. Ivarsen, J. Haislip, A. Crain, D. Foster, M. Nysewander, and
A. LaCluyze, University of North Carolina at Chapel Hill, on behalf of the
CHASE project (which is part of the Millennium Center for Supernova Science
collaboration), report the discovery of an apparent supernova (mag
approximately 17.1) on an unfiltered image taken on Dec. 31.10 UT with the
0.41-m 'PROMPT 4' telescope located at Cerro Tololo.  The new object is
located at R.A. = 2h48m05s.07 +/- 0".2, Decl. = -13o57'53".1 +/- 0".2 (equinox
2000.0), which is about 14".7 west and 22".1 south of the center of the galaxy
NGC 1103.
     Additional CCD magnitudes for 2011js (unfiltered unless noted otherwise):
2011 Jan. 2.1-Nov. 19.1 UT, [20.5 (CHASE, thirteen stacked 80-s images); Oct.
30.25, [20.2 (CSS); Nov. 17.28, 19.4 (CSS); 29.11, [18.0 (CHASE); 2012 Jan.
1.059, 17.1 (Joseph Brimacombe, Cairns, Australia; remotely using a 51-cm
RCOS telescope + STL11K camera + luminance filter at the New Mexico Skies
Observatory near Mayhill, NM, U.S.A.; position end figures 05s.04, 53".0;
image posted at URL http://www.flickr.com/photos/43846774@N02/6614195023/);
1.07, 16.3 (CHASE).

     J. M. Silverman and A. V. Filippenko, University of California, Berkeley,
report that inspection of a CCD spectrum (range 340-1000 nm), obtained on Jan.
3 UT with the Shane 3-m reflector (+ Kast spectrograph) at Lick Observatory,
shows that PSN J02480496-1357511 = SN 2011js is a young type-II supernova.
The spectrum consists of a blue, nearly featureless continuum along with
somewhat broad Balmer emission lines (FWHM about 2000 km/s for H-alpha; less
for H-beta).  There are also unresolved emission lines, probably from a
superposed H II region having relatively low metallicity.

     M. Stritzinger, Oskar Klein Centre, Stockholm University; A. Pastorello,
Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova; and G.
Pignata, Universidad Andres Bello, on behalf of the Millennium Center for
Supernova Science, report that they obtained a spectrum on Jan. 2.4 UT of
PSN J02480496-1357511 = SN 2011js with the Gemini-South telescope (+ GMOS).
The variable appears to be a type-IIn supernova near peak brightness.  The
spectrum exhibits a prevalent blue continuum with narrow emission features
attributed to H_alpha, H_beta, and Na I D (the latter overimposed on a broad
feature).  Faint and narrow lines associated with Ca II (H & K) are
discernible in absorption, while features related to the Ca II near-infrared
triplet (including a very broad component) are tentatively identified.  The
overall appearance of this object is reminiscent of the early-epoch spectra
of SN 1998S (Fassia et al. 2001, MNRAS 325, 907).


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

                         (C) Copyright 2012 CBAT
2012 January 7                   (CBET 2969)              Daniel W. E. Green