Central Bureau for Astronomical Telegrams
IAUC 2930: 1975n; 3C 120
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Read IAUC 2931
Circular No. 2930
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)
Further observations of separations, position angles and
magnitude differences (cf. IAUC 2927) for the additional nuclei:
Nucleus B. Mar. 13.56 UT, 7", 340o, 1.5 (J. Young and R. Newburn,
Table Mountain Observatory, micrometric and photographic); 17.4,
(60"), 325o, 0 (P. Maley, Houston, Texas); 18.4, 12", 323o, 1
(J. Bortle, Brooks Observatory).
Nucleus C. Mar. 13.56 UT, 5", 295o, 0.2 (Young and Newburn); 17.4,
(30"), 294o, 2 (Maley); 18.4, 8", 295o, 0.7 (Bortle).
Nucleus D. Mar. 13.56 UT, 3"-4", 0o, 2.0. (Young and Newburn);
17.4, (30"), 342o, 1 (Maley); 18.4, 6", 333o, 2 (Bortle).
Z. Sekanina, Center for Astrophysics, finds that the reported
positions of the companions seem to indicate the following sequence
of splitting: nucleus B separated from nucleus A on Feb. 22 under a
relative deceleration of 5 x 10**-5 units of solar attraction; nucleus
D probably separated from B on Feb. 25 under an acceleration of
3 x 10**-5 (or, less probably, from A around Feb. 17 under a deceleration
of 2 x 10**-5); and nucleus C, which may be short lived, separated
from A on Mar. 5 under a deceleration of 40 x 10**-5. Predicted
separations and position angles (relative to nucleus A) follow:
1976 ET Nucleus B Nucleus C Nucleus D
Mar. 13 8" 334o 3" 297o 4" 348o
23 14 320 13 292 6 330
Apr. 2 20 314 25 289 8 323
12 26 309 38 286 11 318
22 31 305 50 283 13 314
3C 120
G. Wlerick, Observatoire de Meudon, communicates the following
photoelectric observations of the optical counterpart of the variable
radio source 3C 120 = PKS 0430+05, obtained by R. Gamier, B.
Westerlund and himself at the European Southern Observatory. The
object is fainter than was previously recorded.
Diaphragm 15".5 Diaphragm 62"
1976 V B-V U-B V B-V U-B
Jan. 31 15.01 +0.61 -0.75 14.37 +0.74 -0.47
Feb. 6 15.05 +0.67 -0.77 14.37 +0.78 -0.39
1976 March 19 (2930) Brian G. Marsden
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