[IAUC] CBET 1714: 20090308 : SUPERNOVAE 1996aq AND 2004dk

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                                                  Electronic Telegram No. 1714
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVAE 1996aq AND 2004dk
     C. J. Stockdale, M. S. Heim, and C. M. Vandrevala, Marquette University;
F. E. Bauer, Columbia University; S. D. Van Dyk, Spitzer Science Center,
California Institute of Technology; K. W. Weiler, Naval Research Laboratory;
D. Pooley, University of Wisconsin; S. Immler, Goddard Space Flight Center,
NASA; and V. Dwarkadas, University of Chicago, report the detection of radio
emission near the positions of the type-Ib/Ic supernovae 1996aq (cf. IAUC 6454,
6458) and 2004dk (cf. IAUC 8377, 8379, 8404) with the Very Large Array (VLA)
radio telescope in the "B" configuration in February 2009.  They also report
the results of archival VLA observations.  Radio upper limits are 3-sigma
limits, and x-ray upper limits are 3-sigma limits.

     VLA observations of SN 1996aq in NGC 5584:
Date UT          Fluxes, mJy (frequencies, GHz)
1996 Oct.  5     < 0.36 (8.5); < 0.62 (4.9)
1997 Jan. 23     < 0.24 (8.5); < 0.30 (4.9)
1997 Feb.  9     < 0.17 (8.5)
2003 Oct. 17     < 0.14 (8.5)  [Soderberg et al. (2006), Ap.J. 638, 930]
2009 Feb. 11.5   0.30 +/- 0.05 (4.9)
2009 Feb. 23.3   0.13 +/- 0.03 (8.5); 0.30 +/- 0.03 (4.9); 0.88 +/- 0.08 (1.4)

     Swift observations of 1996aq totalling about 120,000 s during 2007
Mar.-Aug. yield a flux of < 1.1 x 10^(-14) erg/s/cm^2.

     VLA Observations of SN 2004dk in NGC 6118:
Date UT          Fluxes, mJy (frequencies, GHz)
1990 July 30     < 0.22 (4.9)
2004 Oct.  4.1   < 0.70 (22); < 0.66 (15); 0.41 +/- 0.07 (8.5);
                      0.53 +/- 0.08 (4.9)
2004 Oct. 17.9   < 0.66 (15); 0.29 +/- 0.06 (8.5); 0.47 +/- 0.06 (4.9)
2005 Feb. 12.3   < 0.18 (8.5); < 0.70 (4.9)
2009 Feb. 12.6   0.22 +/- 0.06 (4.9)
2009 Feb. 24.5   0.19 +/- 0.03 (8.6); 0.21 +/- 0.03 (4.9); 0.39 +/- 0.09 (1.4)

In a B-configuration VLA observation made on 1990 July 30, no source was
detected within 1 arcminute of the position of SN 2004dk, with a 3-sigma
upper limit of 0.22 mJy at 4.86 GHz.  X-ray fluxes for 2004dk in units of
10^(-14) erg/s/cm^2:  2004 Aug. 12, 2.7 +/- 0.8 (exposure about 26,000 s with
XMM; Pooley et al. 2007, AIPC 937, 381); 2006 Jan. 22, < 5.6 (exposure about
11,000 s with Swift).
     The measured position of the radio emission of SN 1996aq is R.A. =
14h22m22s.71, Decl. = -0o23'23".7 (equinox 2000.0), in excellent agreement
with the re-measured optical position by Kushida and Kushida (end figures
22s.72, 23".8) given on IAUC 6454.  The measured position of the radio
emission of SN 2004dk is R.A. = 16h21m48s.87, Decl. = -2o16'17".6 (equinox
2000.0), in good agreement with the measured optical position by Graham and
Li (end figures 48s.93, 17".3) given on IAUC 8377.   For SN 2004dk, Patat
et al. (IAUC 8379) reported a type-Ic optical spectrum, and Filippenko
et al. (IAUC 8404) measured a type-Ib optical spectrum roughly one month
after Patat et al.
     The radio emission is likely arising from the interaction of the
supernova shock with a dense circumstellar medium (CSM).  Further radio and
x-ray observations should allow us to probe how the CSM has evolved, as the
faster-moving Wolf-Rayet wind has interacted and mixed with the older, denser,
and slower-moving RSG wind (Dwarkardas 2005, Ap.J. 630, 892; 2007, Ap.J. 667,
226).  Since there have only been a few late-time, radio-emitting supernovae
observed, further observations at all wavelengths are encouraged.


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                         (C) Copyright 2009 CBAT
2009 March 8                     (CBET 1714)              Daniel W. E. Green