Central Bureau for Astronomical Telegrams
IAUC 2943: 1975n
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Circular No. 2943
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Cable Address: SATELLITES, NEWYORK
Western Union: RAPID SATELLITE CAMBMASS
COMET WEST (1975n)
The following precise positions have been reported:
1976 UT R. A. (1950) Decl. m1 Observer
Mar. 14.15660 21 16 40.65 + 9 57 45.5 3.3 Bielicki
17.33237 21 09 49.79 +10 47 30.0 Mourao
19.11818 21 06 35.24 +11 11 47.8 3.8 Bielicki
19.14782 21 06 32.14 +11 12 10.2 "
23.18050 21 00 18.97 +12 01 24.6 Codina
23.19647 21 00 17.60 +12 01 35.9 "
26.17642 20 56 19.86 +12 34 26.4 "
26.19587 20 56 18.62 +12 34 35.8 "
30.14928 20 51 30.71 +13 15 14.4 Milet
30.15074 20 51 30.50 +13 15 16.0 "
30.15429 20 51 30.82 +13 15 11.1 "
30.16295 20 51 30.16 +13 15 17.8 "
31.13083 20 50 22.15 +13 24 53.6 "
31.13233 20 50 22.12 +13 24 54.9 "
31.13666 20 50 22.77 +13 24 49.1 "
31.15502 20 50 21.41 +13 24 59.6 "
31.15590 20 50 21.14 +13 25 01.9 Codina
31.18785 20 50 19.07 +13 25 22.0 "
Apr. 2.14591 20 48 04.47 +13 44 05.0 Milet
2.14744 20 48 04.44 +13 44 05.2 "
7.78438 20 41 35.13 +14 35 46.8 Tomita
8.50561 20 40 44.30 +14 42 12.2 Giclas
10.50075 20 38 21.37 +14 59 23.9 "
12.79977 20 35 31.14 +15 18 49.0 Tomita
M. Bielicki (Warsaw Observatory). Micrometric. Nucleus A and/or D.
R. R. de F. Mourao (National Observatory, Rio de Janeiro). Probably
nucleus D.
J. M. Codina (Fabra Observatory). Evidently nucleus A and/or D.
B. Milet (Nice Observatory). Mar. 30 and 31: first pair nucleus B,
second pair nucleus A and D. Apr. 2: probably nucleus A.
K. Tomita (Tokyo Astronomical Observatory). Definitely nucleus A.
H. L. Giclas (Lowell Observatory). 33-cm photographic telescope.
Measurer: M. L. Kantz. Evidently nucleus A.
Further photographic observations of the separations and position
angles of the additional nuclei (relative to nucleus A):
Nucleus B. Mar. 15.55 UT, 9".6, 336o (E. Harlan, C. Gaskell and A.
Klemola, Lick Observatory); 20.54, 13".6, 322o (Harlan et al.);
21.54, 15".0, 320o (Harlan et al.); 23.55, 16".5, 319o (Harlan et
al.); 26.54, 17".6, 319o (Harlan et al.); 27.54, 18".6, 316o
(Harlan et al.); 30.52, 20".8, 315o (Harlan et al.); Apr. 7.43,
25".2, 311o (A. Ketelsen, University of Iowa); 7.78, 25".1
313o (Tomita); 8.34, 26".1, 310o (G. Schwartz, Harvard Observatory;
measured by Z. Sekanina); 10.42, 26".4, 310o (Ketelsen);
12.80, 29".6, 309o (Tomita); 14.50, 30".3, 309o (S. Murrell and C.
Knuckles, New Mexico State University; measured by E. J. Reese);
19.44, 34".1, 306o (Murrell et al.).
Nucleus C. Mar. 20.54 UT, 10".3, 296o (Harlan et al.).
Nucleus D. Mar. 15.55 UT, 4".6, 358o (Harlan et al.); 20.54, 6".6,
338o (Harlan et al.); 21.54, 7".2, 336o (Harlan et al.); 23.55,
6".5, 330o (Harlan et al.); 25.54, 7".7, 331o (Harlan et al.);
26.54, 8".4, 334o (Harlan et al.); 27.54, 8".7, 331o (Harlan et
al.); 30.52, 9".5, 331o (Harlan et al.); Apr. 2.15, 11".8, 316o
(Milet); 7.43, 11".1, 323o (Ketelsen); 7.78, 11".2, 329o (Tomita);
8.34, 11".2, 324o (Schwartz); 10.42, 11".5, 324o (Ketelsen); 12.80,
12".9, 323o (Tomita); 14.50, 13".0, 322o (Murrell et al.); 19.44,
14".4, 320o (Murrell et al.).
Z. Sekanina, Center for Astrophysics, refines and extends the
calculations on IAUC 2930 as follows. Nucleus D separated from
nucleus A on Feb. 13.7 +/- 0.4 UT under a relative deceleration of
(2.85 +/- 0.03) x 10**-5 units of solar attraction; B separated from A
on Feb. 22.5 +/- 0.1 under a deceleration of (5.19 +/- 0.02) x 10**-5;
and C, which indeed turned out to be short lived, separated from A
on Mar. 5.8 +/- 0.3 under a deceleration of (38 +/- 3) x 10**-5. It is
still possible that B and D separated from A as a single fragment
and that B separated from D on Feb. 26.7 +/- 0.2 under a deceleration
of (4.30 +/- 0.12) x 10**-5. Predicted separations and position angles
of B and D (relative to nucleus A; equinox 1950.0) continue:
1976 ET Nucleus B Nucleus D 1976 ET Nucleus B Nucleus D
Apr. 22 34"9 305o4 14"9 315o9 June 1 49"7 295o2 21"6 302o7
May 2 40.7 302.1 17.3 311.8 11 48.5 294.9 21.6 301.4
12 45.5 299.1 19.4 308.1 21 45.7 296.0 20.8 301.3
22 48.7 296.7 20.9 305.0 July 1 42.3 298.6 19.6 302.4
E. Gerard, I. Kazes and R. Lauque report that observations
with the Nancay radio telescope show that the OH line at 1667 MHz
has changed from emission to absorption as expected from solar
ultraviolet fluorescence. The average peak flux density on Apr. 17
and 18 was -0.06 +/- 0.02 Jy and the line width 3.5 +/- 1 km/s.
Selected recent total visual magnitude estimates and tail
information: Apr. 10.33 UT, 5.9, 2o in p.a. 270o (K. Simmons, Switzerland,
Florida, 7 x 50 binoculars); 11.08, 7.1, 8' in 265o (F.
Popperl, Bad Reichenhall, Germany, 20-cm reflector); 13.44, 6.1, 3o
(A. Hale, Alamogordo, New Mexico, 10 x 50 binoculars); 18.35, 7.3,
15' in 280o (P. Collins, Concord, Massachusetts, 12-cm refractor).
1976 April 20 (2943) Brian G. Marsden
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