Central Bureau for Astronomical Telegrams
IAUC 5776: 1993J; P/SCHWASSMANN-WACHMANN 1
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Circular No. 5776
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
S. D. Van Dyk and K. W. Weiler, Naval Research Laboratory; R.
A. Sramek and M. P. Rupen, National Radio Astronomy Observatory;
and N. Panagia, Space Telescope Science Institute, report: "New
observations of SN 1993J made on Apr. 22.47 UT with the Very Large
Array in 'B' configuration show that the source currently has a
flux density at 1.3 cm (22.5 GHz) of 39.94 +/- 0.53 mJy; the radio
light curve at this frequency appears to be flattening as expected
from preliminary model predictions (IAUC 5762). A slow decline in
the flux density at 1.3 cm should commence shortly. The supernova
also has flux densities of 37.35 +/- 0.34 mJy at 2.0 cm (14.9 GHz),
11.77 +/- 0.07 mJy at 3.6 cm (8.4 GHz), and 1.70 +/- 0.07 mJy at 6
cm (4.86 GHz). This flux density evolution is consistent with
previous model estimates (IAUC 5762) to within the predictive capability
of the model from the few data points available at that time.
Revised estimates will be issued shortly. Radio monitoring is
continuing on a nearly daily basis at these and other wavelengths in
order to follow the supernova's rapidly changing behavior."
B. Jannuzi, Institute for Advanced Study; G. Schmidt, Steward
Observatory; R. Elston, Cerro Tololo Interamerican Observatory; and
P. Smith, Steward Observatory, report: "Optical polarization was
detected from SN 1993J on Apr. 26.12 UT using the CCD spectropolarimeter
of Steward Observatory on the Kitt Peak Mayall 4-m telescope.
Over the wavelength interval 400-735 nm, the polarization averages
1.04 percent at a position angle of 29 deg, but considerable structure
is present through the strong emission lines. Dilution of the
continuum polarization is apparent at H-alpha, but a 10-deg rotation
in position angle through the middle of the remarkable double-
peaked profile implies that the line flux is intrinsically polarized.
Polarization is a new phenomenon in SN 1993J, as P. Smith
obtained a V-band value of 0.19 +/- 0.11 percent at 178 +/- 17 deg
on Apr. 7.22 UT using the Two-Holer polarimeter on the Steward
Observatory 1-m telescope. Observations of nearby stars confirm that
interstellar polarization in the direction of the supernova is less
than 0.1 percent."
PERIODIC COMET SCHWASSMANN-WACHMANN 1
CCD V total magnitudes from H. Mikuz, Ljubljana, Slovenia
(0.20-m Baker-Schmidt camera): Apr. 8.82 UT, 13.3; 22.83, 12.6;
23.84, 12.8.
1993 April 28 (5776) Daniel W. E. Green
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