Central Bureau for Astronomical Telegrams
IAUC 2768: P/PERRINE-MRKOS; 1975d
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Read IAUC 2769
Circular No. 2768
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
PERIODIC COMET PERRINE-MRKOS
The prediction below, by B. G. Marsden, is from an orbit
fitted to observations at the 1962 and 1968 returns, with perturbations
by all nine planets taken into account. Although the prediction
by R. Luss in Handb. Br. Astron. Assoc. for 1975 is very similar,
the comet's past behavior suggests that a large Delta-T correction
is not improbable.
T = 1975 Aug. 2.8779 ET Epoch = 1975 Aug. 16.0 ET
Peri. = 166.4950 e = 0.638226
Node = 239.9074 1950.0 a = 3.580887 AU
Incl. = 17.8103 n = 0.1454515
q = 1.29547 AU P = 6.776 years
For dT = +1d
1975 ET R. A. (1950) Decl. Delta r dR.A. dDecl. m2
May 8 0 08.87 +14 27.9 2.279 1.643 -1m65 - 5'9 20.5
18 0 38.51 +17 17.3 -1.82 - 5.4
28 1 10.21 +19 59.9 2.089 1.517 -1.99 - 4.5 19.8
June 7 1 44.13 +22 28.8 -2.15 - 3.2
17 2 20.26 +24 36.0 1.936 1.411 -2.31 - 1.3 19.2
27 2 58.36 +26 13.1 -2.42 + 1.0
July 7 3 37.98 +27 12.7 1.827 1.335 -2.49 + 3.7 18.7
17 4 18.35 +27 29.3 -2.48 + 6.5
27 4 58.54 +27 00.6 1.760 1.298 -2.41 + 9.1 18.4
Aug. 6 5 37.64 +25 48.0 -2.28 +11.3
16 6 14.86 +23 56.4 1.727 1.305 -2.11 +12.9 18.4
26 6 49.64 +21 32.5 -1.92 +13.8
Sept. 5 7 21.72 +18 44.0 1.714 1.355 -1.73 +14.1 18.6
15 7 50.96 +15 38.4 -1.56 +13.8
25 8 17.39 +12 22.4 1.706 1.441 -1.42 +13.1 19.0
Oct. 5 8 41.12 + 9 01.4 -1.30 +12.1
15 9 02.18 + 5 39.7 1.690 1.555 -1.21 +10.9 19.5
25 9 20.65 + 2 20.9 -1.14 + 9.6
Nov. 4 9 36.51 - 0 52.5 1.657 1.686 -1.10 + 8.3 20.0
14 9 49.68 - 3 58.0 -1.08 + 7.0
24 10 00.04 - 6 53.1 1.604 1.828 -1.09 + 5.8 20.5
Dec. 4 10 07.40 - 9 35.2 -1.12 + 4.7
14 10 11.50 -12 00.8 1.540 1.976 -1.18 + 3.9 20.9
m2 = 15.5 + 5 log Delta + 15 log r
The total magnitude m1 could reach 15 in July or August.
COMET BRADFIELD (1975d)
Mr. D. Herald, Woden, near Canberra, provides the following
precise positions. He remarks that the comet has a fanshaped tail
and that a condensation of m2 ~ 12 was apparent after April 3.
1975 UT R. A. (1950) Decl. m1
Mar. 30.39757 2 19 09.83 -19 19 36.5
30.39931 2 19 10.28 -19 19 35.6
Apr. 3.39097 2 36 35.41 -18 26 37.1
3.39792 2 36 36.90 -18 26 33.4
4.38924 2 40 59.23 -18 12 28.0
4.39167 2 41 00.46 -18 12 28.8
6.40556 2 49 55.82 -17 42 47.2 9.0
6.40903 2 49 56.81 -17 42 48.7
The following parabolic elements, by the undersigned, are from
12 observations Mar. 13 to Apr. 6:
T = 1975 Apr. 4.632 ET Peri. = 264.182
Node = 157.236 1950.0
q = 1.21632 AU Incl. = 55.262
1975 ET R. A. (1950) Decl. Delta r m1
Apr. 18 3 42.17 -14 26.6 1.838 1.234 8.7
23 4 04.74 -12 51.2
28 4 27.10 -11 11.9 1.850 1.269 8.9
May 3 4 49.07 - 9 30.7
8 5 10.53 - 7 49.9 1.898 1.322 9.1
13 5 31.37 - 6 11.3
18 5 51.50 - 4 36.8 1.979 1.388 9.4
23 6 10.85 - 3 07.7
28 6 29.39 - 1 45.0 2.088 1.466 9.8
June 2 6 47.13 - 0 29.3
7 7 04.07 + 0 39.1 2.220 1.553 10.1
12 7 20.23 + 1 40.2
17 7 35.64 + 2 34.2 2.368 1.647 10.5
22 7 50.34 + 3 21.4
27 8 04.36 + 4 02.2 2.524 1.746 10.9
m1 = 6.5 + 5 log Delta + 10 log r
Mr. T. B. Tregaskis, Mount Eliza, Victoria, writes that on
Mar. 22.424 UT he observed the comet at total magnitude about 9.5
(using a 32-cm reflector at 150 x). The comet was very faint,
diffuse, 2' in diameter, round, with very slight condensation (less
than on Mar. 13) and no tail.
1975 April 15 (2768) Brian G. Marsden
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