[IAUC] CBET 554: 20060621 : SUPERNOVA 2006dd IN NGC 1316

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                                                  Electronic Telegram No. 554
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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CBAT en CFA.HARVARD.EDU (science)
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SUPERNOVA 2006dd IN NGC 1316
     S. Immler, Goddard Space Flight Center, NASA, and Universities Space
Research Association; P. Milne, Steward Observatory, University of
Arizona; and P. J. Brown, Pennsylvania State University -- on behalf
of the Swift-satellite team -- report on Swift Ultraviolet/Optical Telescope
(UVOT) and X-Ray Telescope (XRT) observations of SN 2006dd (cf. CBET 553)
obtained on June 20.71 UT.  They confirm, via comparison to Digitized Sky
Survey images, the detection of a new object at R.A. = 03h22m41s.64, Decl.
= -37o12'13".2 (equinox 2000.0), consistent with the position reported by
Monard on CBET 553; the following UVOT magnitudes were measured for 2006dd
(statistical and systematic errors are 0.1 mag each):  V = 14.0 (167-s
exposure), B = 14.5 (259 s), U = 13.7 (258 s), UVW1 [181-321 nm] = 15.5 (520
s), UVM2 [166-268 nm] = 17.9 (881 s), and UVW2 [112-264 nm] = 18.1 (881 s).
Comparison to the photometry obtained on June 20.158 (B = 14.66, V = 14.41,
from CBET 553) shows that the supernova is still pre-maximum.  The B-V and
U-B colors are similar to those of SN 2006bp (type II-P) before maximum
(Immler and Brown, http://www.astronomerstelegram.org/?read=793).
Furthermore, comparison of the colors with other supernovae from Poznanski
et al. (2002, PASP 114, 833) indicates that 2006dd is a young type-II
supernova before or around maximum.
     No x-ray source is detected at the position of 2006dd in a simultaneous
4100-s XRT observation.  The 3-sigma upper limit to the XRT net count rate
is 8.0 x 10^(-3) counts/s, corresponding to a (0.2- to 10-keV) x-ray flux
and luminosity of < 4.0 x 10^(-13) ergs/cm/cm/s and < 2.9 x 10^(40) ergs/s,
respectively, for an adopted thermal plasma spectrum with a temperature of
kT = 10 keV, a Galactic foreground column density of N_H = 1.89 x 10^(20)
(Dickey and Lockman, 1990, ARAA 28, 215), and a distance of 24.5 Mpc (z =
0.00587; Longhetti et al. 1998, A.Ap. Suppl. 130, 267, via NED).  No further
Swift observations are scheduled due to sun-angle constraints.


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                         (C) Copyright 2006 CBAT
2006 June 21                     (CBET 554)               Daniel W. E. Green