[IAUC] CBET 2656: 20110215 : SUPERNOVAE 2011X, 2011Y, AND 2011Z

Mie Sep 14 16:19:05 ART 2011

                                                  Electronic Telegram No. 2656
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


SUPERNOVAE 2011X, 2011Y, AND 2011Z
     [Note:  this text replaces that on CBET 2652]
     G. Pignata and M. Cifuentes, Universidad Andres Bello; J. Maza, M. Hamuy,
R. Antezana, L. Gonzalez, R. Cartier, F. Forster, S. Silva, F. Carrasco, P.
Sanchez, and C. Hervias, Universidad de Chile; P. Gonzalez, Pontificia
Universidad Catolica de Chile (for SN 2011X only); 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,
report the discovery of three supernovae on unfiltered CCD images obtained
with the 0.41-m 'PROMPT' telescopes located at Cerro Tololo; SN 2011X was
found with the 'PROMPT 5' telescope, and the other two supernovae were found
with the 'PROMPT 3' telescope.  The discovery observations are tabulated below
(positional uncertainty in the range +/- 0".2 to 0".3 in each coordinate):

 SN       2011 UT       R.A. (2000.0) Decl.      Mag.      Offset
 2011X    Jan. 15.25   13 50 21.36  -52 39 58.5   17.3    63" W, 20" S
 2011Y    Jan. 27.07    8 12 58.25  -27 34 15.7   17.3       --
 2011Z    Jan. 29.25   13 30 43.04  -20 57 14.0   16.1    1".0 W, 8".3 S

     Additional approximate unfiltered CHASE magnitudes for 2011X (designated
PSN J13502136-5239585 on the Central Bureau's TOCP webpage), which is thought
to be connected with the galaxy ESO 221-7 = PGC 49121:  2009 June 4.06-2010
Aug. 14.07 UT, [21.0 (thirty 40-s archival images taken over this time span);
2011 Jan. 16.29, 17.2.
     Additional approximate unfiltered CHASE magnitudes for 2011Y (designated
PSN J08125825-2734157 on the Central Bureau's TOCP webpage), for which the
faintness of the presumed host galaxy does not allow the measurement of
reliable offsets between the supernova's position and the center of the
galaxy:  2010 Dec. 31.23, [18.0; 2011 Jan. 8.18, [18.0; 28.05, 17.3.
     Additional approximate unfiltered CHASE magnitudes for 2011Z (designated
PSN J13304304-2057140 on the Central Bureau's TOCP webpage), which is thought
to be connected with the galaxy ESO 576-77 = PGC 47494:  2010 Feb. 11.29,
[18.5; June 27.02, [17.0; 2011 Feb. 2.28, (visible, but no mag provided).

     M. Stritzinger, Oskar Klein Centre, Stockholm University; N. Morrell, Las
Campanas Observatory; J. Anderson, F. Foerster, and M. Hamuy, Universidad de
Chile; G. Pignata, Universidad Andres Bello; and G. Folatelli, University of
Tokyo; on behalf of the Millennium Center for Supernova Science, report that
they have obtained spectra (range 432.5-965.9 nm) of these three supernovae
on Mar. 5.1 UT with the Magellan I Baade 6.5-m telescope (+ IMACS) at Las
Campanas Observatory.  The spectrum of SN 2011X indicates that it is an evolved
type-IIP supernova; best matches with the "Supernova Identification" code
(SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) suggest that 2011X is at least
3-4 months old.  SN 2011Y is a normal type-Ia supernova around maximum light;
adopting for the host galaxy a recession velocity of 20385 km/s (as derived by
the SNID code, based on the spectral features of the supernova), an expansion
velocity of 11000 km/s is computed from the absorption minima of the Si II
635.5-nm line.
     SN 2011Z is a type-Ia supernova before maximum light.  Cross-correlation
with a library of supernova spectra using SNID provides a close match to the
sub-luminous supernova 1986G (Phillips et al. 1987, PASP 99, 592).  Adopting a
SNID-derived host recession velocity of 6595 km/s, expansion velocities of
10500 km/s and 11000 km/s are derived from the absorption minima of the Si II
597.1- and 635.5-nm lines, respectively.


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

                         (C) Copyright 2011 CBAT
2011 February 15                 (CBET 2656)              Daniel W. E. Green