Orbital Elements

The Orbital Elements of selected visual binaries

The binaries are arranged by constellation. The seven orbital elements allow one to calculate the position of a companion to its primary, for any desired date. The process isn't terribly difficult, and is found in Peter Duffett-Smith's Practical Astronomy With Your Calculator. The given positions ("ephemerides") are those for 1 January 2000.
The Orbital Elements columns contain the following information:

Constellation: the list contains 26 different constellations.
Star: the star's name. If a link, it contains a drawn orbit.
ADS: the reference number as found in the Aitken Double Star catalogue.
P: the period, that is, the number of years for the companion to make a complete revolution.
[This entry, and the next six, constitute the "orbital elements"]
If an asterisk (*) is in the "P" column, the orbit has been recently revised and the latest element values are used.
T: the epoch of periastron.
a: the semimajor axis of the orbit (arcsecs).
e: the eccentricity.
i: the inclination of the orbit.
w: the longitude of the periastron.
W: the position angle of the ascending node.
Ephemerides: the position of the companion in the year 2000. Any separation over 1.0" is generally visible to medium-powered telescopes. Less than that may be difficult to resolve.

There are five basic factors for resolving binaries:

the distance between the two components;

the size of a telescope's objective;

the apparent magnitudes of the stars in question;

the condition of the atmosphere;

the skills of the observer.

Visual Binaries: the orbital elements

Constellation Star ADS P T a e i w W Ephemerides
Andromeda Groombridge 34 246 2600 1745 41.15 0.0 61.4 0.0 45.3 2000: 64º, 36.3"

" Struve 73 755 164.7 1957.15 1.014 0.31 46.4 4.65 171.5 2000: 313º, 0.9"

" Gamma² 1630 61.1 1952.1 0.296 0.93 111.1 171.15 104.15 2000: 103º, 0.4"

" Struve 3050 17149 350* 2037.0 3.19 0.51 67 50 353.2 2000: 332º, 1.9"

Aquarius Zeta²-Zeta¹ 15971 760* 1968.0 4.507 0.50 135.87 63.42 304.64 2000: 198º, 2.0"

Bootes Struve 1785 9031 155.75* 1916.75 2.433 0.446 47.4 200.0 155.4 2000: 173º, 3.3"

" Zeta 9343 123.44 1897.59 0.595 0.9572 142.0 1.47 129.99 2000: 300º, 0.8"

" Xi 9413 151.505 1909.361 4.904 0.512 140.04 203.92 348.1 2000: 318º, 6.6"

" Struve 1909 9494 220* 2017 3.70 0.451 83.7 37.5 57.7 2000: 54º, 2.2"
" Mu^2BC 9626 246.04* 1864.5 1.40 0.570 136.6 338.5 176.0 2000: 7º, 2.1"

Cancer Zeta^AB 6650 59.50* 1989.23 0.880 0.325 165 204 30.4 2000: 83º, 0.8"

" Zeta^ABxC 6650 1115* 1970 7.70 0.24 146.0 345.5 74.2 2000: 73º, 5.9"

Canes Venatici Struve 1768 8974 240 1863.95 1.091 0.83 144 137.9 67 2000: 99, 1.8"

Canis Major Alpha 5423 50.09 1894.13 7.5 0.592 136.53 147.27 44.57 2000: 150º, 4.6"

Cassiopeia Struve 3062 61 106.83 1943.05 1.432 0.45 44.4 278.8 219.1 2000: 328º, 1.5"

Centaurus Alpha^AB -- 79.92 1955.56 17.583 0.516 79.24 231.56 204.87 2000: 222º, 14.2"

" Gamma -- 84.50 1931.22 0.93 0.79 112.9 187.8 2.4 2000: 347º, 1.0"

Cepheus Xi 15600 3800 1750 11.5 0.24 109 114 85 2000: 275º, 8.2"

" Kruger 60 15972 44.67* 1970.22 2.383 0.41 167.2 211.0 154.5 2000: 95º, 3.0"

Cetus β395 520 25 1924 0.67 0.22 78 142 112 2000: 289º, 0.5"

" Struve 186 1538 170.3 1893.35 1.05 0.71 73.6 220.7 40.4 2000: 60º, 1.1"

Coma Berenices Struve 1639 8539 678 1891 1.3 0.95 161 334 105.7 2000: 327º, 1.6"

Corona Australis h5014 -- 191.2 1841.68 1.062 0.52 145.2 190.4 49.2 2000: 346º, 0.9"

Corona Borealis Eta 9617 41.56 1892.39 0.839 0.28 58.9 219.6 24.2 2000: 65º, 0.7"

" Sigma 9979 1000 1828 6.599 0.78 33.3 84.35 7.7 2000: 237º, 7.1"

Cygnus Delta 12880 827.6 1885.8 3.2 0.49 147 134 98.7 2000: 222º, 2.5"

" 61 14636 653.34 1676.94 24.307 0.4002 55.01 147.03 171.4 2000: 150º, 30.3"

" Tau 14787 49.9 1939.6 0.88 0.25 134.2 119 159.7 2000: 306º, 0.8"

" Mu 15270 789* 1958.0 5.32 0.66 75.5 145.7 110.1 2000: 308º, 1.8"

Delphinus Beta 14073 26.65 1962.72 0.475 0.35 63.6 346.4 178.6 2000: 343º, 0.5"

Draco 20 10279 729.35 1853.5 1.38 0.466 97 220.3 66.2 2000: 68º, 1.4"

" Mu 10345 672* 1949 3.945 0.45 144.7 197.0 282.8 2000: 18º, 2.2"

" 26 10660 76 1950.4 1.52 0.16 105.7 322 152 2000: 331º, 1.7"

Eridanus Omicron^2BC 3093 251.988 1848.872 7.0453 0.4147 108.54 326.497 150.96 2000: 336º, 9.3"

" p -- 483.66 1813.494 7.8169 0.53444 142.82 18.374 13.116 2000: 191º, 11.5"

Fornax Alpha 2402 314 1947 4.37 0.76 81.5 42 117.7 2000: 299º, 5.1"

Gemini Alpha 6175 467* 1958.0 6.805 0.343 114.5 249.5 41.3 2000: 65º, 3.9"

" Delta 5983 1200 1487 6.975 0.11 63.28 57.19 18.4 2000: 225º, 5.8"

" 38 5559 3190 1636 9.55 0.48 148.4 310.5 185.6 2000: 144º, 7.1"

Hercules Alpha 10418 3600 3635 4.68 0 155.8 180 119.6 2000: 104º, 4.6"

" Zeta 10157 34.45* 1967.78 1.365 0.464 131.6 291.9 229.2 2000: 12º, 0.73"

" 99 11077 55.8 1941.8 1.00 0.74 32.0 300.6 218.7 2000: 250º, 0.5"

Hydra Epsilon^ABxC 6953 990* 1920 4.66 0.30 39 200 49.3 2000: 298º, 2.9"

" β411 7846 210.1 1948.23 0.9824 0.80 126.1 35.8 144.8 2000: 315º, 1.4"

Leo Gamma¹ 7724 618.6 1743.32 2.505 0.84 36.4 162.5 143.2 2000: 125º, 4.4"

" Iota 8148 192 1948.47 1.92 0.55 130.5 140 52.2 2000: 116º, 1.7"

Lupus Gamma -- 147 1887 0.59 0.49 95.6 301 92.8 2000: 274º, 0.7"

Lynx 12 5400 699 1740 1.66 0.03 180 154.8 0 2000: 69º, 1.7"

" Struve 1338 7307 289.05* 1996.77 1.459 0.61 47.8 252.9 91.5 2000: 289º, 1.0"

" Kui 37 -- 21.80* 1971.91 0.638 0.149 132.5 212.0 24.5 2000: 45º, 0.6"

Lyra Epsilon^1AB 11635 1165 1152.4 2.78 0.19 138 165.7 29 2000: 350º, 2.6"

" Epsilon^2CD 11635 585 1644.5 2.95 0.49 120.5 88 17.4 2000: 82º, 2.3"

" β648 11871 61.15* 1972.35 1.262 0.258 114.8 283.6 48.13 2000: 317º, 0.7"

Musca Beta -- 383.12 1872.29 1.735 0.526 61.3 98.32 161.81 2000: 43º, 1.3"

Ophiuchus Eta 10374 88 1936.8 0.86 0.84 100.4 279.8 41.4 2000: 244º, 0.6"

" Lambda 10087 129.87 1939.54 0.97 0.618 26.8 158.9 52.5 2000: 30º, 1.5"

" Tau 11005 280 1829 1.494 0.72 59.3 49.78 63 2000: 284º, 1.7"

" 36 10417 548.7 1643.48 13.91 0.9 99.2 90 93.6 2000: 147º, 4.9"

" 70 11046 88.30* 1984.30 4.560 0.495 120.8 13.2 301.4 2000: 149º, 3.7"

Orion Zeta 4263 1509 2070.6 2.728 0.07 72 47.3 155.5 2000: 165º, 2.3"

Pegasus 37 15988 140 1908 0.75 0.51 89 202.3 117.2 2000: 118º, 0.7"

" 85 17175 26.27 1910.11 0.83 0.38 50 94.4 288.6 2000: 184º, 0.7"

Pisces Alpha 1615 933.05 2098.64 4 0.696 120.9 225.4 23.3 2000: 272º, 1.8"

Puppis β101 6420 23.30* 1915.71 0.58 0.69 77.8 67.7 103.3 2000: 331º, 0.25"

Scorpius Alpha 10074 878 1461 2.9 0.1 90 0 93.7 2000: 274º, 2.6"

" Xi 9909 45.69 1951.14 0.72 0.74 36.9 348.2 201.7 2000: 308º, 0.4"

Sculptor Epsilon 1394 1192 2076.2 4.652 0 180 0 0 2000: 23º, 4.7"

" Tau -- 1875.6 1968.6 12.395 0.9832 77.82 85.39 138 2000: 340º, 2.1"

Serpens Delta 9701 3168 1700 6.02 0.31 112.6 274.6 166.8 2000: 176º, 4.4"

Taurus 80 3264 189.5 1888 1.01 0.83 108 162 12.8 2000: 17º, 1.8"

" Struve 422 2644 2101 1900 8.023 0.18 32.1 152 92 2000: 269º, 6.7"

Ursa Major Xi 8119 59.84 1935.17 2.53 0.414 122.65 127.53 101.59 2000: 273º, 1.8"

" Sigma² 7203 1067 1917.7 6.2 0.81 146.2 331.5 99.7 2000: 354º, 3.9"

" β1082 8739 115.7 1921.74 1.256 0.44 51.5 301 269.2 2000: 69º, 1.5"

Vela Psi -- 33.99 1935.75 0.795 0.44 58.5 48.4 287.2 2000: 264º, 0.5"

Virgo Gamma 8630 168.68 2005.13 3.697 0.885 148.0 256.5 36.9 2000: 260º, 1.45"

Vulpecula Struve 2525 12447 990 1887.9 1.97 0.93 133.7 8.5 103.1 2000: 291º, 2.1"

Last updated 16 May 2001

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© 1999-2001 by Richard Dibon-Smith and meant for personal use only.

Constellation	Star	ADS	P	T	a	e	i	w	W	Ephemerides
Andromeda	Groombridge 34	246	2600	1745	41.15	0.0	61.4	0.0	45.3	2000: 64º, 36.3"
"	Struve 73	755	164.7	1957.15	1.014	0.31	46.4	4.65	171.5	2000: 313º, 0.9"
"	Gamma²	1630	61.1	1952.1	0.296	0.93	111.1	171.15	104.15	2000: 103º, 0.4"
"	Struve 3050	17149	350*	2037.0	3.19	0.51	67	50	353.2	2000: 332º, 1.9"
Aquarius	Zeta²-Zeta¹	15971	760*	1968.0	4.507	0.50	135.87	63.42	304.64	2000: 198º, 2.0"
Bootes	Struve 1785	9031	155.75*	1916.75	2.433	0.446	47.4	200.0	155.4	2000: 173º, 3.3"
"	Zeta	9343	123.44	1897.59	0.595	0.9572	142.0	1.47	129.99	2000: 300º, 0.8"
"	Xi	9413	151.505	1909.361	4.904	0.512	140.04	203.92	348.1	2000: 318º, 6.6"
"	Struve 1909	9494	220*	2017	3.70	0.451	83.7	37.5	57.7	2000: 54º, 2.2"
"	Mu^2BC	9626	246.04*	1864.5	1.40	0.570	136.6	338.5	176.0	2000: 7º, 2.1"
Cancer	Zeta^AB	6650	59.50*	1989.23	0.880	0.325	165	204	30.4	2000: 83º, 0.8"
"	Zeta^ABxC	6650	1115*	1970	7.70	0.24	146.0	345.5	74.2	2000: 73º, 5.9"
Canes Venatici	Struve 1768	8974	240	1863.95	1.091	0.83	144	137.9	67	2000: 99, 1.8"
Canis Major	Alpha	5423	50.09	1894.13	7.5	0.592	136.53	147.27	44.57	2000: 150º, 4.6"
Cassiopeia	Struve 3062	61	106.83	1943.05	1.432	0.45	44.4	278.8	219.1	2000: 328º, 1.5"
Centaurus	Alpha^AB	--	79.92	1955.56	17.583	0.516	79.24	231.56	204.87	2000: 222º, 14.2"
"	Gamma	--	84.50	1931.22	0.93	0.79	112.9	187.8	2.4	2000: 347º, 1.0"
Cepheus	Xi	15600	3800	1750	11.5	0.24	109	114	85	2000: 275º, 8.2"
"	Kruger 60	15972	44.67*	1970.22	2.383	0.41	167.2	211.0	154.5	2000: 95º, 3.0"
Cetus	β395	520	25	1924	0.67	0.22	78	142	112	2000: 289º, 0.5"
"	Struve 186	1538	170.3	1893.35	1.05	0.71	73.6	220.7	40.4	2000: 60º, 1.1"
Coma Berenices	Struve 1639	8539	678	1891	1.3	0.95	161	334	105.7	2000: 327º, 1.6"
Corona Australis	h5014	--	191.2	1841.68	1.062	0.52	145.2	190.4	49.2	2000: 346º, 0.9"
Corona Borealis	Eta	9617	41.56	1892.39	0.839	0.28	58.9	219.6	24.2	2000: 65º, 0.7"
"	Sigma	9979	1000	1828	6.599	0.78	33.3	84.35	7.7	2000: 237º, 7.1"
Cygnus	Delta	12880	827.6	1885.8	3.2	0.49	147	134	98.7	2000: 222º, 2.5"
"	61	14636	653.34	1676.94	24.307	0.4002	55.01	147.03	171.4	2000: 150º, 30.3"
"	Tau	14787	49.9	1939.6	0.88	0.25	134.2	119	159.7	2000: 306º, 0.8"
"	Mu	15270	789*	1958.0	5.32	0.66	75.5	145.7	110.1	2000: 308º, 1.8"
Delphinus	Beta	14073	26.65	1962.72	0.475	0.35	63.6	346.4	178.6	2000: 343º, 0.5"
Draco	20	10279	729.35	1853.5	1.38	0.466	97	220.3	66.2	2000: 68º, 1.4"
"	Mu	10345	672*	1949	3.945	0.45	144.7	197.0	282.8	2000: 18º, 2.2"
"	26	10660	76	1950.4	1.52	0.16	105.7	322	152	2000: 331º, 1.7"
Eridanus	Omicron^2BC	3093	251.988	1848.872	7.0453	0.4147	108.54	326.497	150.96	2000: 336º, 9.3"
"	p	--	483.66	1813.494	7.8169	0.53444	142.82	18.374	13.116	2000: 191º, 11.5"
Fornax	Alpha	2402	314	1947	4.37	0.76	81.5	42	117.7	2000: 299º, 5.1"
Gemini	Alpha	6175	467*	1958.0	6.805	0.343	114.5	249.5	41.3	2000: 65º, 3.9"
"	Delta	5983	1200	1487	6.975	0.11	63.28	57.19	18.4	2000: 225º, 5.8"
"	38	5559	3190	1636	9.55	0.48	148.4	310.5	185.6	2000: 144º, 7.1"
Hercules	Alpha	10418	3600	3635	4.68	0	155.8	180	119.6	2000: 104º, 4.6"
"	Zeta	10157	34.45*	1967.78	1.365	0.464	131.6	291.9	229.2	2000: 12º, 0.73"
"	99	11077	55.8	1941.8	1.00	0.74	32.0	300.6	218.7	2000: 250º, 0.5"
Hydra	Epsilon^ABxC	6953	990*	1920	4.66	0.30	39	200	49.3	2000: 298º, 2.9"
"	β411	7846	210.1	1948.23	0.9824	0.80	126.1	35.8	144.8	2000: 315º, 1.4"
Leo	Gamma¹	7724	618.6	1743.32	2.505	0.84	36.4	162.5	143.2	2000: 125º, 4.4"
"	Iota	8148	192	1948.47	1.92	0.55	130.5	140	52.2	2000: 116º, 1.7"
Lupus	Gamma	--	147	1887	0.59	0.49	95.6	301	92.8	2000: 274º, 0.7"
Lynx	12	5400	699	1740	1.66	0.03	180	154.8	0	2000: 69º, 1.7"
"	Struve 1338	7307	289.05*	1996.77	1.459	0.61	47.8	252.9	91.5	2000: 289º, 1.0"
"	Kui 37	--	21.80*	1971.91	0.638	0.149	132.5	212.0	24.5	2000: 45º, 0.6"
Lyra	Epsilon^1AB	11635	1165	1152.4	2.78	0.19	138	165.7	29	2000: 350º, 2.6"
"	Epsilon^2CD	11635	585	1644.5	2.95	0.49	120.5	88	17.4	2000: 82º, 2.3"
"	β648	11871	61.15*	1972.35	1.262	0.258	114.8	283.6	48.13	2000: 317º, 0.7"
Musca	Beta	--	383.12	1872.29	1.735	0.526	61.3	98.32	161.81	2000: 43º, 1.3"
Ophiuchus	Eta	10374	88	1936.8	0.86	0.84	100.4	279.8	41.4	2000: 244º, 0.6"
"	Lambda	10087	129.87	1939.54	0.97	0.618	26.8	158.9	52.5	2000: 30º, 1.5"
"	Tau	11005	280	1829	1.494	0.72	59.3	49.78	63	2000: 284º, 1.7"
"	36	10417	548.7	1643.48	13.91	0.9	99.2	90	93.6	2000: 147º, 4.9"
"	70	11046	88.30*	1984.30	4.560	0.495	120.8	13.2	301.4	2000: 149º, 3.7"
Orion	Zeta	4263	1509	2070.6	2.728	0.07	72	47.3	155.5	2000: 165º, 2.3"
Pegasus	37	15988	140	1908	0.75	0.51	89	202.3	117.2	2000: 118º, 0.7"
"	85	17175	26.27	1910.11	0.83	0.38	50	94.4	288.6	2000: 184º, 0.7"
Pisces	Alpha	1615	933.05	2098.64	4	0.696	120.9	225.4	23.3	2000: 272º, 1.8"
Puppis	β101	6420	23.30*	1915.71	0.58	0.69	77.8	67.7	103.3	2000: 331º, 0.25"
Scorpius	Alpha	10074	878	1461	2.9	0.1	90	0	93.7	2000: 274º, 2.6"
"	Xi	9909	45.69	1951.14	0.72	0.74	36.9	348.2	201.7	2000: 308º, 0.4"
Sculptor	Epsilon	1394	1192	2076.2	4.652	0	180	0	0	2000: 23º, 4.7"
"	Tau	--	1875.6	1968.6	12.395	0.9832	77.82	85.39	138	2000: 340º, 2.1"
Serpens	Delta	9701	3168	1700	6.02	0.31	112.6	274.6	166.8	2000: 176º, 4.4"
Taurus	80	3264	189.5	1888	1.01	0.83	108	162	12.8	2000: 17º, 1.8"
"	Struve 422	2644	2101	1900	8.023	0.18	32.1	152	92	2000: 269º, 6.7"
Ursa Major	Xi	8119	59.84	1935.17	2.53	0.414	122.65	127.53	101.59	2000: 273º, 1.8"
"	Sigma²	7203	1067	1917.7	6.2	0.81	146.2	331.5	99.7	2000: 354º, 3.9"
"	β1082	8739	115.7	1921.74	1.256	0.44	51.5	301	269.2	2000: 69º, 1.5"
Vela	Psi	--	33.99	1935.75	0.795	0.44	58.5	48.4	287.2	2000: 264º, 0.5"
Virgo	Gamma	8630	168.68	2005.13	3.697	0.885	148.0	256.5	36.9	2000: 260º, 1.45"
Vulpecula	Struve 2525	12447	990	1887.9	1.97	0.93	133.7	8.5	103.1	2000: 291º, 2.1"

The Orbital Elements of selected visual binaries

There are five basic factors for resolving binaries:

The Main Menu:

All files of The Constellations Web Page are © 1999-2001 by Richard Dibon-Smith and meant for personal use only.

All files of The Constellations Web Page are
© 1999-2001 by Richard Dibon-Smith and meant for personal use only.