Central Bureau for Astronomical Telegrams
IAUC 2900: P/D'ARREST; gamma Cas
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Read IAUC 2901
Circular No. 2900
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 D'ARREST
The following prediction, derived by B. G. Marsden from
observations during 1950-1971 and with consideration of perturbations
by all nine planets and nongravitational effects, differs slightly
from that in Handb. Br. Astron. Assoc. for 1976. The uncertainty
is several times this difference, possibly up to Delta-T = +/- 0.2 day
(cf. Marsden et al. 1973, Astron. J. 78, 211).
T = 1976 Aug 12.8401 ET Epoch = 1976 Aug. 10.0 ET
Peri. = 178.9271 e = 0.656142
Node = 141.3513 1950.0 a = 3.385149 AU
Incl. = 16.6898 n = 0.1582477
q = 1.164009 AU P = 6.228 years
For dT = +1d
1976/77 ET R. A. (1950) Decl. Delta r dR.A. dDecl. m2
Feb. 12 16 03.00 - 3 46.4 2.256 2.349 -1m21 + 4'5 21.0
22 16 18.74 - 3 18.7 -1.38 + 4.9
Mar. 3 16 34.34 - 2 35.0 1.875 2.191 -1.57 + 5.4 20.3
13 16 49.66 - 1 34.0 -1.80 + 5.9
23 17 04.63 - 0 14.6 1.517 2.029 -2.07 + 6.5 19.5
Apr. 2 17 19.09 + 1 24.1 -2.40 + 7.1
12 17 32.90 + 3 22.3 1.195 1.867 -2.81 + 7.8 18.6
22 17 45.97 + 5 39.4 -3.31 + 8.5
May 2 17 58.15 + 8 13.5 0.918 1.706 -3.93 + 9.0 17.6
12 18 09.37 +11 00.4 -4.70 + 9.3
22 18 19.70 +13 53.9 0.688 1.550 -5.65 + 8.9 16.6
June 1 18 29.26 +16 43.9 -6.84 + 7.4
11 18 38.56 +19 16.0 0.502 1.407 -8.28 + 4.1 15.5
21 18 48.54 +21 11.9 -10.04 - 1.3
July 1 19 00.71 +22 04.6 0.349 1.286 -12.17 - 8.8 14.3
6 19 08.41 +21 55.0 -13.40 -13.1
11 19 17.77 +21 12.6 0.283 1.238 -14.78 -17.2 13.7
16 19 29.31 +19 47.4 -16.34 -20.6
21 19 43.65 +17 26.0 0.224 1.201 -18.11 -22.3 13.1
26 20 01.47 +13 50.9 -20.13 -20.9
31 20 23.47 + 8 43.4 0.178 1.176 -22.41 -15.1 12.5
Aug. 5 20 50.09 + 1 53.2 -24.90 - 4.8
10 21 21.12 - 6 24.6 0.153 1.165 -27.42 + 6.8 12.1
15 21 55.30 -15 15.5 -29.62 +12.4
20 22 30.36 -23 23.0 0.160 1.168 -31.01 + 5.7 12.2
25 23 03.66 -29 51.5 -31.16 -12.0
30 23 33.08 -34 28.4 0.196 1.185 -29.98 -32.8 12.7
Sept. 4 23 57.61 -37 29.5 -27.75 -49.6
9 0 17.16 -39 18.6 0.249 1.215 -24.98 -59.7 13.3
14 0 32.20 -40 16.0 -22.11 -63.3
19 0 43.48 -40 36.0 0.313 1.257 -19.42 -62.3 14.0
29 0 57.82 -39 57.4 -14.93 -53.7
Oct. 9 1 05.61 -38 07.6 0.463 1.369 -11.58 -42.9 15.2
19 1 10.39 -35 31.7 -9.08 -33.4
29 1 14.41 -32 25.1 0.649 1.508 -7.19 -26.1 16.3
Nov. 8 1 18.98 -29 00.8 -5.76 -20.7
18 1 24.59 -25 29.3 0.877 1.661 -4.66 -16.8 17.4
28 1 31.48 -21 57.7 -3.81 -13.9
Dec. 8 1 39.64 -18 31.4 1.154 1.821 -3.16 -11.7 18.4
18 1 48.93 -15 13.7 -2.65 -10.0
28 1 59.24 -12 06.3 1.476 1.983 -2.25 - 8.7 19.3
Jan. 7 2 10.43 - 9 10.5 -1.93 - 7.5
17 2 22.34 - 6 26.4 1.833 2.145 -1.67 - 6.6 20.1
27 2 34.87 - 3 54.2 -1.46 - 5.8
Feb. 6 2 47.93 - 1 33.7 2.212 2.304 -1.29 - 5.0 20.8
16 3 01.41 + 0 35.4 -1.15 - 4.4
26 3 15.25 + 2 33.4 2.599 2.460 -1.03 - 3.9 21.5
m2 = 15.5 + 5 log Delta + 10 log r
J. Bortle, Brooks Observatory, notes that this comet has undergone
considerable brightness surges closely following perihelion
passage at almost every apparition. Based on a study of observations
1857-1970, and assuming the maximum of the surge to occur 20
days after perihelion, he provides the following predictions for m1:
1976 ET m1 1976 ET m1 1976 ET m1
June 11 13.5 Aug. 10 9.2 Oct. 9 8.8
July 1 12.3 20 8.4 29 10.5
11 11.7 30 6.2 Nov. 18 11.8
21 11.1 Sept. 9 6.7 Dec. 8 13.2
31 10.5 19 7.4
gamma CASSIOPEIAE
J. G. Jernigan, Massachusetts Institute of Technology, reports
that the SAS-3 Group has discovered x-ray emission from a
region centered 10" from gamma Cas (with error-circle radius 1'.0). The
time-averaged 2-11 keV x-ray flux during 1975 Dec. 30.04-1976 Jan.
1.21 UT was 3.5 x 10**-10 erg cm**-2 s**-1. The source is designated
MX0053+60, and the failure to detect it in previous x-ray surveys
shows that it is variable. Information about the optical behavior
of gamma Cas during the above interval would be useful.
1976 January 13 (2900) Brian G. Marsden
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