Central Bureau for Astronomical Telegrams
IAUC 3805: 1983d
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Read IAUC 3806
Circular No. 3805
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM Telephone 617-864-5758
COMET IRAS-ARAKI-ALCOCK (1983d)
R. P. Boyle, Vatican Observatory Group, Steward Observatory,
reports that observations on May 5.6 and 6.6 UT with the Vatican
polarimeter on the 1-m telescope on Mt. Lemmon showed the linear
polarization to be 25 percent in V, R and I, and somewhat less in
U and B, a narrow-band (5 nm) filter at 385 nm giving 13 percent.
B. L. Lutz, Lowell Observatory; and R. M. Wagner, Ohio State
University, report spatially resolved spectrophotometric observations
between 380 and 640 nm at a nominal resolution of 0.8 nm.
Image-dissector-scanner spectra with the 1.8-m Perkins reflector
on May 5 and 6 showed the coma to exhibit the characteristic emissions
of CN, C3, C2, NH2 and [O I]. The nuclear region, which appeared
highly condensed, showed a strong reflective continuum
superimposed on the gaseous emissions. The observations were made
with a spatial resolution of 7" (~ 700 km projected on the comet)
at several positions both sunward and antisunward within a radius
of 1' (6000 km) of the condensed region.
Naked-eye estimates of total magnitude and coma diameter: May
9.90 UT, 3.2, 55' (R. McNaught, Herstmonceux); 10.37, 2.6, 2.6 deg (D.
Machholz, Loma Prieta, CA); 11.16, 2.4, 3 deg (D. W. E. Green, MA).
The following further improved parabolic orbital elements,
determined by the undersigned from observations Apr. 27 to May 11,
should yield an ephemeris correct to 0'2. It is still not
possible to determine the orbital eccentricity unequivocally.
Epoch 1983 May 14.0 ET
T = 1983 May 21.1891 ET Peri. = 192.7860
Node = 48.3993 1950.0
q = 0.991373 AU Incl. = 73.3733
1983 ET R.A. (1950.0) Decl. p r m1
May 16 7 44.81 -30 19.6 0.118 0.995 4.8
21 7 31.75 -37 48.9
26 7 26.67 -40 10.2 0.365 0.995 7.3
31 7 23.82 -41 18.3
June 5 7 21.99 -41 58.4 0.604 1.024 8.5
10 7 20.80 -42 26.3
15 7 20.05 -42 48.9 0.826 1.079 9.4
20 7 19.62 -43 10.2
25 7 19.45 -43 32.4 1.028 1.155 10.2
1983 May 11 (3805) Brian G. Marsden
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