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IAUC 4458: V1500 Cyg; 1987u; 1987s

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                                                  Circular No. 4458
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 617-495-7244/7440/7444


V1500 CYGNI
     G. D. Schmidt, Steward Observatory, University of Arizona;
and H. S. Stockman, Space Telescope Science Institute, write: "We
have confirmed our detection of optical circular polarization from
the 1975 nova V1500 Cyg (IAUC 4415).  Preliminary analysis of data
obtained over a four-night run in Sept. 1987 reveals that the
polarized flux is modulated on a coherent period of 198.1 +/- 0.4 min,
which we take to be the rotational period of the magnetic white-
dwarf primary.  This is 1.5 percent (7 sigma) shorter than the 201.1-
min photometric period that is likely due to the heated inner
hemisphere of a corotating secondary.  It appears that the
superposition of emission components that are individually modulated at
these two periods can explain much of the complex photometric history
of this object since its outburst (see, e.g., Patterson 1979,
Ap.J. 231, 789)."


COMET RUDENKO (1987u)
     Total visual magnitude estimates: Aug. 26.11 UT, 10.1 (D.
Levy, Amherst, MA, 0.15-m refractor; correction to IAUC 4448);
Sept. 14.76, 8.8 (M. Antal, Hurbanovo, Czechoslovakia, 25 x 100
binoculars); 16.78, 8.6 (Antal); 18.30, 8.4 (G. W. Wolf, Wellington,
New Zealand, 0.06-m refractor); 20.11, 8.1 (A. Hale, Las
Cruces, NM, 0.41-m reflector); 24.10, 8.3 (E. A. Jacobson,
Evansville, MN, 0.25-m reflector); 25.08, 8.4: (Jacobson).


COMET BRADFIELD (1987s)
     E. P. Moore, New Mexico Institite of Mining and Technology;
and D. A. Klinglesmith, NASA Goddard Space Flight Center, communicate
the following tail lengths and position angles, measured from
10-min exposures with the 0.35-m Schmidt telescope at the Joint
Observatory for Cometary Research, Socorro: Sept. 12.124 UT, 15',
115 deg; 13.116, 20', 116 deg; 20.110, 20', 110 deg; 20.119, 20', 109 deg;
21.109, 15', 115 deg; 21.119, 20', 109 deg.
     Total visual magnitudes: Sept. 14.72, 7.9 (J. Campos, Durban,
R.S.A., 0.13-m refractor); 16.79, 8.3 (Antal); 18.31, 8.2 (Wolf);
20.17, 7.5 (C. S. Morris, Lockwood Valley, CA, 20 x 80 binoculars);
22.12, 7.6 (R. A. Keen, Boulder, CO, 8 x 40 binoculars);
24.11, 7.6 (Keen); 26.02, 7.3 (G. R. Chester, Rixeyville, VA,
0.20-m reflector); 27.15, 6.9 (Morris).


1987 September 29              (4458)              Brian G. Marsden

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