Central Bureau for Astronomical Telegrams

IAUC 8489: 2004et; 2004dj

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                                                  Circular No. 8489
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)


SUPERNOVA 2004et IN NGC 6946
     J. Fabbri, University College, London; and B. Sugerman, Space
Telescope Science Institute, on behalf of the 'Survey for Evolution
of Emission from Dust in Supernovae' (SEEDS) collaboration (M.
Barlow, principal investigator), report the detection of the
type-II supernova 2004et in archival Spitzer spacecraft 'InfraRed
Array Camera' (IRAC) images of NGC 6946 obtained by the 'Spitzer
Infrared Nearby Galaxy Survey' (SINGS) Legacy program (cf.
Kennicutt et al. 2003, PASP 115, 928) taken on 2004 Nov. 25.7 UT,
or 56 days after discovery.  A source was detected in all four IRAC
bands at R.A. = 20h35m25s.38, Decl. = +60o07'17".8 (equinox 2000.0;
+/- 0".3 in each coordinate), in close agreement with the optical
(IAUC 8413) and radio positions (IAUC 8415).  The measured flux
densities (mJy) at 3.6, 4.5, 5.8, and 8.0 microns are 21.9 +/- 1.7,
13.8 +/- 0.8, 10.0 +/- 0.4, and 6.7 +/- 0.3, respectively.  Given
the proximity of NGC 6946 (6 Mpc) and the rapid mid-infrared
variability of the similarly-aged SN 2004dj (see below), this
supernova should be closely monitored at all wavelengths.


SUPERNOVA 2004dj in NGC 2403
     Sugerman, again on behalf of the SEEDS collaboration, also
reports the detection of the type-IIP supernova 2004dj in archival
Spitzer images of NGC 2403 taken by the SINGS Legacy project and by
S. Van Dyk et al.  A source is detected in all IRAC bands at R.A. =
7h37m17s.04, Decl. = +65o35'57".9 (equinox 2000.0; +/- 0".3 in each
coordinate), in close agreement with the optical position (IAUC
8377).  The epochs (UT), days since discovery, and flux densities
(mJy) from the pipeline-calibrated images at 3.6, 4.5, 5.8, and 8.0
microns are: 2004 Oct. 7.1, 68, 10.3 +/- 1.0, 7.9 +/- 0.6, 6.9 +/-
0.3, 4.2 +/- 0.2; Oct. 12.1, 73, 7.6 +/- 0.9, 8.8 +/- 0.4, 5.9 +/-
0.2, 3.4 +/- 0.2; Nov. 1.1, 93, 4.8 +/- 0.4, 7.0 +/- 0.4, 4.6 +/-
0.2, 2.5 +/- 0.1.  The supernova is marginally detected in the
Mid-Infrared Photometry and Spectrograph 24-micron imager in the
wings of a bright, extended region located 19".5 away at p.a. 152
deg.  Dates of observation, days after discovery, and estimated
flux densities (mJy) are:  2004 Oct. 12.9, 73, 0.5 +/- 0.3; Oct.
14.5, 75, 0.8 +/- 0.3; Nov. 6.7, 98, 0.8 +/- 0.3.  Follow-up
observations should continue at all wavelengths to monitor these
rapid (< 5 days) variations.

                      (C) Copyright 2005 CBAT
2005 February 28               (8489)            Daniel W. E. Green

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