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:

  1. Constellation: the list contains 26 different constellations.
  2. Star: the star's name. If a link, it contains a drawn orbit.
  3. ADS: the reference number as found in the Aitken Double Star catalogue.
  4. 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.
  5. T: the epoch of periastron.
  6. a: the semimajor axis of the orbit (arcsecs).
  7. e: the eccentricity.
  8. i: the inclination of the orbit.
  9. w: the longitude of the periastron.
  10. W: the position angle of the ascending node.
  11. 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.

  • 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

    ConstellationStarADSPTaei w WEphemerides
    AndromedaGroombridge 342462600174541.150.061.40.0 45.32000: 64, 36.3"
    "Struve 73755164.71957.151.0140.3146.44.65171.52000: 313, 0.9"
    "Gamma2163061.11952.10.2960.93111.1171.15104.152000: 103, 0.4"
    "Struve 305017149350*2037.03.190.516750353.22000: 332, 1.9"
    AquariusZeta2-Zeta115971 760*1968.04.5070.50 135.8763.42304.642000: 198, 2.0"
    BootesStruve 17859031155.75*1916.752.4330.44647.4200.0155.42000: 173, 3.3"
    "Zeta9343123.441897.590.5950.9572 142.01.47129.992000: 300, 0.8"
    "Xi9413151.5051909.3614.9040.512 140.04203.92348.12000: 318, 6.6"
    "Struve 19099494220*20173.700.451 83.737.557.72000: 54, 2.2"
    "Mu2BC9626246.04*1864.51.400.570 136.6338.5176.02000: 7, 2.1"
    CancerZetaAB665059.50*1989.230.8800.325 16520430.42000: 83, 0.8"
    "ZetaABxC66501115*19707.700.24 146.0345.574.22000: 73, 5.9"
    Canes VenaticiStruve 176889742401863.951.0910.83 144137.9672000: 99, 1.8"
    Canis MajorAlpha542350.091894.137.50.592 136.53147.2744.572000: 150, 4.6"
    CassiopeiaStruve 306261106.831943.051.4320.45 44.4278.8219.12000: 328, 1.5"
    CentaurusAlphaAB--79.921955.5617.5830.516 79.24231.56204.872000: 222, 14.2"
    "Gamma--84.501931.220.930.79 112.9187.82.42000: 347, 1.0"
    CepheusXi156003800175011.50.24 109114852000: 275, 8.2"
    "Kruger 601597244.67*1970.222.3830.41167.2211.0154.52000: 95, 3.0"
    Cetusβ3955202519240.670.22 781421122000: 289, 0.5"
    "Struve 1861538170.31893.351.050.71 73.6220.740.42000: 60, 1.1"
    Coma BerenicesStruve 1639853967818911.30.95 161334105.72000: 327, 1.6"
    Corona Australish5014--191.21841.681.0620.52 145.2190.449.22000: 346, 0.9"
    Corona BorealisEta961741.561892.390.8390.28 58.9219.624.22000: 65, 0.7"
    "Sigma9979100018286.5990.78 33.384.357.72000: 237, 7.1"
    CygnusDelta12880827.61885.83.2 0.4914713498.72000: 222, 2.5"
    "6114636653.341676.94 24.3070.400255.01147.03171.42000: 150, 30.3"
    "Tau1478749.9 1939.60.880.25134.2119 159.72000: 306, 0.8"
    "Mu15270789*1958.05.32 0.6675.5145.7110.12000: 308, 1.8"
    DelphinusBeta1407326.651962.720.475 0.3563.6346.4178.62000: 343, 0.5"
    Draco2010279729.351853.5 1.380.46697220.366.22000: 68, 1.4"
    "Mu10345672*19493.945 0.45144.7197.0282.82000: 18, 2.2"
    "2610660761950.41.52 0.16105.73221522000: 331, 1.7"
    EridanusOmicron2BC 3093251.9881848.8727.04530.4147 108.54326.497150.962000: 336, 9.3"
    "p--483.661813.4947.81690.53444 142.8218.37413.1162000: 191, 11.5"
    FornaxAlpha24023141947 4.370.7681.542117.72000: 299, 5.1"
    GeminiAlpha6175467*1958.06.8050.343114.5 249.541.32000: 65, 3.9"
    "Delta5983120014876.9750.1163.28 57.1918.42000: 225, 5.8"
    "385559319016369.550.48 148.4310.5185.62000: 144, 7.1"
    HerculesAlpha10418360036354.680 155.8180119.62000: 104, 4.6"
    "Zeta1015734.45*1967.781.3650.464 131.6291.9229.22000: 12, 0.73"
    "991107755.81941.81.000.74 32.0300.6218.72000: 250, 0.5"
    HydraEpsilonABxC6953990*19204.660.30 3920049.32000: 298, 2.9"
    "β4117846210.11948.230.98240.80 126.135.8144.82000: 315, 1.4"
    LeoGamma17724618.61743.322.5050.84 36.4162.5143.22000: 125, 4.4"
    "Iota81481921948.471.920.55 130.514052.22000: 116, 1.7"
    LupusGamma--14718870.590.49 95.630192.82000: 274, 0.7"
    Lynx12540069917401.660.03 180154.802000: 69, 1.7"
    "Struve 13387307289.05*1996.771.4590.61 47.8252.991.52000: 289, 1.0"
    "Kui 37--21.80*1971.910.6380.149 132.5212.024.52000: 45, 0.6"
    LyraEpsilon1AB1163511651152.42.780.19 138165.7292000: 350, 2.6"
    "Epsilon2CD116355851644.52.950.49 120.58817.42000: 82, 2.3"
    "β6481187161.15*1972.351.2620.258 114.8283.648.132000: 317, 0.7"
    MuscaBeta--383.121872.291.7350.526 61.398.32161.812000: 43, 1.3"
    OphiuchusEta10374881936.80.860.84 100.4279.841.42000: 244, 0.6"
    "Lambda10087129.871939.540.970.618 26.8158.952.52000: 30, 1.5"
    "Tau1100528018291.4940.72 59.349.78632000: 284, 1.7"
    "3610417548.71643.4813.910.9 99.29093.62000: 147, 4.9"
    "701104688.30*1984.304.5600.495 120.813.2301.42000: 149, 3.7"
    OrionZeta426315092070.62.7280.07 7247.3155.52000: 165, 2.3"
    Pegasus371598814019080.750.51 89202.3117.22000: 118, 0.7"
    "851717526.271910.110.830.3850 94.4288.62000: 184, 0.7"
    PiscesAlpha1615933.052098.6440.696120.9 225.423.32000: 272, 1.8"
    Puppisβ101642023.30*1915.710.580.6977.8 67.7103.32000: 331, 0.25"
    ScorpiusAlpha1007487814612.90.190 093.72000: 274, 2.6"
    "Xi990945.691951.140.720.7436.9 348.2201.72000: 308, 0.4"
    SculptorEpsilon139411922076.24.65201800 02000: 23, 4.7"
    "Tau--1875.61968.612.3950.983277.82 85.391382000: 340, 2.1"
    SerpensDelta9701316817006.020.31112.6 274.6166.82000: 176, 4.4"
    Taurus803264189.518881.010.83108 16212.82000: 17, 1.8"
    "Struve 4222644210119008.0230.1832.1 152922000: 269, 6.7"
    Ursa MajorXi811959.841935.172.530.414122.65 127.53101.592000: 273, 1.8"
    "Sigma2720310671917.76.20.81146.2 331.599.72000: 354, 3.9"
    "β10828739115.71921.741.2560.4451.5 301269.22000: 69, 1.5"
    VelaPsi--33.991935.750.7950.4458.5 48.4287.22000: 264, 0.5"
    VirgoGamma8630168.682005.13 3.6970.885148.0 256.536.92000: 260, 1.45"
    VulpeculaStruve 2525124479901887.91.970.93133.7 8.5103.12000: 291, 2.1"

    Last updated 16 May 2001

    Or go to

    The Main Menu:

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