Central Bureau for Astronomical Telegrams
IAUC 5751: 1993J
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Circular No. 5751
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
SUPERNOVA 1993J IN NGC 3031
R. Fesen and J. Thorstensen, Dartmouth College, report that
spectra (range 440-800 nm) of SN 1993J taken Mar. 31.1 and Apr. 1.1
UT using the MDM Observatory 2.4-m telescope show faint, broad
emission features with peaks near 495, 586, and 656 nm. If the
656-nm feature is due to H-alpha, its FWZI implies a Doppler width
of +/- 10 000 km/s; its equivalent width increased from 0.7 nm on
Mar. 31 to 1.0 nm on Apr. 1. The 586-nm feature extends to 565 nm,
but its red edge was indistinct. If interpreted as He I 587.6 nm,
the blue extent corresponds to a velocity of 12 000 km/s.
S. Benetti, G. Contarini, R. Gratton and M. Turatto, Asiago
Astrophysical Observatory, communicate: "We have taken high-resolution
(0.035 nm) spectra of SN 1993J with the echelle spectrograph
at Cima Ekar on Mar. 31.0 UT. The narrow H-alpha emission at
656.14 nm (corresponding to a heliocentric velocity of -82 km/s) is
resolved (FWHM 0.45 nm, or 200 km/s), and the EW is 0.034 nm, in
agreement with that on IAUC 5736. No defined structure of the line
is shown. We also observed weak emissions due to He II at 468.41
nm (EW 0.008 nm), [Fe X] at 637.22 nm (FWHM 0.10 nm, EW = 0.009
nm), and [Fe XIV] at 530.06 nm (FWHM 0.09 nm, EW = 0.003 nm).
Various absorption components of the Na I D lines were observed (at
-115 km/s, EW(D1) = 0.0164 nm, EW(D2) = 0.0127 nm; at +133 km/s,
EW(D1) = 0.0396 nm, EW(D2) = 0.0331 nm), in good agreement with IUE
observations of Mg I on IAUC 5738. Other blended components are
also present. The Na I column densities for the clouds responsible
for the two measured components are log n(Na I) = 12.48 and 13.02,
respectively, using the doublet ratio method and gaussian line
profiles. This suggests a reddening of E(B-V) between 0.1 and 0.4
(Gratton and Sneden 1987, A.Ap. 204, 193)."
G. G. Pooley and D. A. Green, Mullard Radio Astronomy
Observatory, Cambridge, write: "Using observations made with the Ryle
telescope during Apr. 5.631-5.898 UT, we have detected radio emission
from SN 1993J at a frequency of 15 GHz. The flux density was
about 3 mJy, with strong evidence for increasing flux density during
the observations. No emission was detected during observations
at similar hour angles the previous day. The position of the
detected emission is within 1" of the optical position reported on
IAUC 5737."
1993 April 6 (5751) Daniel W. E. Green
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