[IAUC] CBET 2756: 20110630 : SUPERNOVA 2011dw IN PGC 58436 = PSN J16313945+4129229

[quai en eps.harvard.edu]

                                                  Electronic Telegram No. 2756
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 2011dw IN PGC 58436 = PSN J16313945+4129229
     A. Pelloni, J. Newton, and T. Puckett report the discovery of an apparent
supernova (mag 17.5) on an unfiltered CCD image (limiting mag 19.0) taken with
a 0.35-m reflector at Portal, AZ, U.S.A., on June 24.3395 UT in the course
of the Puckett Observatory Supernova Search.  The new object, which was
confirmed at mag 16.9 on June 27.3391 by Puckett with the 40-cm reflector at
Portal, is located at R.A. = 16h31m39.45 Decl. = +41o29'22".9 (equinox 2000.0),
which is 17".3 east and 14".0 south of the center of PGC 58436.  Nothing is
visible at this position on images taken by Puckett on 2011 June 9 (limiting
mag 19.1).  The variable was designated PSN J16313945+4129229 when posted on
the Central Bureau's TOCP webpage and is here designated SN 2011dw based on
the spectroscopic report below.  Puckett has posted a finder image for 2011dw
at website URL http://possdata.com/PSNJ16313945+4129229.jpg.

     D. C. Leonard, San Diego State University; J. Moustakas, University of
California at San Diego; B. J. Swift and D. McCarthy, University of Arizona;
V. Bailey, E. Carrico, A. Carter, E. Chui, E. Douglas, E. Eggeman, R. Goldberg,
R. Grant, K. Hartman, J. Hellerstein, E. Hooper, C. Horlick-Cruz, L. Hunter, T.
Jiles, E. D. Johnson, K. Kumar, L. Lappe, J. Lee, W. Lee, F. Marsh, G. Mehta,
P. Miller, R. Rampalli, J. Reed, K. Rice, H. Saldivar, M. Salgado-Flores, A.
Schlingman, W. F. Schlingman, W. M. Schlingman, S. Scibelli, K. Sinclair, I.
Steincamp, N. Stock, N. Todd, L. L. Aizpuru Vargas, S. Yamanaka, and E.
Zachary, 2011 Advanced Teen Astronomy Camp, report that a low-dispersion
optical spectrum (range 370-690 nm) of PSN J16313945+4129229 = SN 2011dw,
obtained with the 2.3-m Bok telescope (+ Boller & Chivens spectrograph) at
Steward Observatory on June 30 UT, displays a featureless, blue continuum.
Identifying a faint, unresolved emission line in the spectrum at 675.8 nm with
H-alpha indicates a redshift of 0.03, in agreement with the recession velocity
reported in the second Sloan Digital Sky Survey Data Release of the putative
host galaxy, PGC 58436.  The spectrum is reminiscent of a very young
type-II/IIb supernova, although additional spectroscopy is required to
confirm the nature of this event.  Adopting the NASA/IPAC Extragalactic
Database distance-modulus estimate of PGC 58436 of m-M = 35.5 magnitudes,
that the apparent magnitude of PSN J16313945+4129229 (16.9 on June 27.3391,
as reported by the discoverers, above) indicates an absolute magnitude of
-18.6, which is a somewhat-greater luminosity than typical type-II/IIb
supernovae achieve.


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

                         (C) Copyright 2011 CBAT
2011 June 30                     (CBET 2756)              Daniel W. E. Green