

1 CURSOR
        [ORBIT\]CURSOR

    Call the graphic cursor for interactive data editing. This allows, among
    other things, to ignore some data points, or to exchange the  two  stars
    (to  correct  180  degrees ambiguities).  For a summary of the supported
    actions, type ? when in cursor mode

1 PERIODOGRAM
        [ORBIT\]PERIODOGRAM Pmin Pmax Nperiods

    Plot the Lomb-Scargle periodogram for the specified period range

1 SAVE
        [ORBIT\]SAVE File_Name

    Save the current data and orbit to a file (usable as input)

    CAUTION: This command does not save whatever  comments/notes  the  input
    file may contain about the individual data points. If there are some and
    they are important to you (as is sually the case...), it's best to manu-
    ally  paste  the  orbit  part of a SAVE output with the data part of the
    original input.


1 READ
        [ORBIT\]READ Filename [/APPEND] [/OLD_FORMAT]

    Read one input file into memory. If /APPEND is specified  the  new  data
    are added to current ones.  Option /OLD_FORMAT provides backward compat-
    ibility with the old "fixed" format (still supported, but deprecated and
    no longer documented).

    The  data files are free format ASCII text, and use a Keyword-Value syn-
    tax. Line order is irrelevant, except  that  the  latest  occurence  has
    precedence  for  keywords  which should only occur once. Any item may be
    omitted and will then take a reasonable default value.  The  exclamation
    mark is the comment character, and formatting details (spaces, number of
    digits...) should not matter.

    The information naturally splits into 3  groups:  initial  orbital  ele-
    ments,  data  items, and auxiliary information (not directly relevant to
    the orbit but useful: system name(s), position, spectral types...).



2 DATA
        Presently supported data items are  parallaxes,  radial  velocities,
    and  visual  measurements (including interferometry). We plan to add as-
    trometric positions of the photocenter and interferometric uv data,  and
    would eventually like to support light-curves of eclipsing binaries.

    Parallaxes  are  considered as data items, and used in the orbit adjust-
    ment as an additional link between physical (i.e. km or km/s) and  angu-
    lar (i.e. arcseconds) quantities. This unifies orbital parallaxes from a
    fully constrained orbit (SB2+visual) with the SB1+visual+parallax  case,
    and this provide an optimal combination in between. Syntax is
    PAR    Value Probable_Error


    Radial  velocities  can be entered either as values (and probable error)
    for one component, or as normalised (i.e. continuum=1) correlation  pro-
    files. The component naming logic is summarised in the small diagram be-
    low: component names can be 1 or 2 for the primary and  secundary  of  a
    binary  system, 11 and 12 for the two inner components of the primary in
    a triple (or symetric quadruple) system, or 21 and 22 for the two  inner
    components  of the secundary. Higher multiplicities could easily be sup-
    ported upon request to the author, should that prove useful.
                           ----0----
                          |         |
                          1         2
                         ---       ---
                        |   |     |   |
                       11   12   21   22

    The correlation profile approach provides  better  handling  of  profile
    blending near crossings, through use of a single profile width and depth
    for the full data set, and considerably reduces the number of degrees of
    freedom  in  the  adjustment.  This  often improves the precision of the
    spectroscopic orbital elements by a factor of two. It  also  spares  the
    user  the  trouble  of  identifying the components in nearly equal-lined
    SB2s, once an approximate orbit is available. It does on the other  hand
    produce a less human-readable data file. Syntax is
    V1       Date  Value Probable_Error
    V2       Date  Value Probable_Error
    V12      Date  Value Probable_Error
    V22      Date  Value Probable_Error
    VCORREL  Date  Npixels Refpix Refval Increment Sigma Val1 Val2 Val3...

    "Visual"  measurements can be specified as 2D separations in rectangular
    (XY, see CAUTION note below on orientation conventions) or  polar  (rho-
    theta)  coordinates,  or  as 1D separations along an arbitrary direction
    (PROJ). The later description is mostly used for 1D speckle data and lu-
    nar occultations. It could in principle also be used (twice) for 2D data
    too, but results in a less readable graphic display. Rectangular coordi-
    nates  are  usually  more  apropriate at small separations (as Rho/Theta
    have strongly non-gaussian error statistics when Rho is less than 5 sig-
    mas or so). Polar coordinates are prefered when focal scale and orienta-
    tion calibration dominate the error budget (i.e. at  large  separations,
    usually),  because  focal scale and orientation typically are known with
    different uncertainties.

    Syntax is:
    rho-theta Date  Rho  Theta Stderr_Rho Stderr_Theta
    XY        Date  X Y Stderr_X Stderr_Y
    PROJ      Date  Posangle Separation Stderr_Sep

    Dates can be specified as Julian_Day-2400000,  calendar  date  (for  in-
    stance     04-MAR-1996/12:34:11.6),     as    ISO-8601    dates    (i.e.
    1997-12-05T07:40:32), or as year and  fraction  of  year  (for  instance
    Y1961.530).


    CAUTION:  X and Y are defined with the binary star observers' convention
    that X is positive towards N and Y is positive towards E. This  is  con-
    sistent  with the astronomical definition of the position angle (i.e. X=
    rho*cos(theta) and Y=rho*sin(theta)), but not with most  peoples's  idea
    of what X and Y should be...

2 ORBITAL ELEMENTS
        Given the non-linear character of the least square orbit adjustment,
    initial values must be specified for the orbital elements. Also, one can
    sometimes  use external constrains (or an educated guess) to fix an oth-
    erwise undetermined parameter (i.e. take the inclination  from  a  light
    curve analysis) and improve/permit a mass determination. All this can be
    done on the command line (using ADJUST or/and FIX)  but  it  is  usually
    more convenient to store these parameters in the data file.

    The syntax for an orbital element line is
    Element_Name   Value  Probable_Error  Status
    Status is either "Fixed" or "Adjustable".

    Supported  orbital  elements  are  listed (and briefly described) in the
    help for ADJUST.

2 AUXILIARY INFORMATION
        A number of things which are irrelevant to the orbit, but convenient
    to have at hand.

    Gl       Gliese_Name
    HD       HD_Number
    NAMES    Other_Names
    RA       HH:MM:SS.S
    DEC      SDD:MM:SS.S
    EQ       Year
    TSA      Spectral_Type for primary
    TSB      Spectral_Type for secundary

2 EXAMPLE

        Gl       Gl 773.3
    RA       19:57:04
    DEC      -10:05.4
    EQ          1950.000
    TSA        F8V
    TSB        G0V
    !
    P          1788.9988      9.3762
    T0        47049.3359     24.2706
    e              .5920       .0167
    as             .1586       .0059
    OM          327.1682      7.1612
    om          318.7169     10.1511
    i            22.0260     10.1786
    K1            2.6006       .2676
    V0           29.8432       .1026
    ! Data
    PAR             .045        .001
    !
    VA       49138.60   30.68   .3
    VA       49183.45   30.52   .3
    rho-theta 49290.37  .1940  79.30  .0100 0.0
    rho-theta 44777.55  .2050 136.90  .0100 0.0
    XY       47700.19  -.0600 .2380   .0200 .0200
    PROJ      47702.29    0.   .2310 .0600   .0040
    PROJ      48049.67    0.   .2300 .0100   .0080
    PROJ      48050.67  -90.  -.1000 .0100   .0020
    VCORREL 50080.12 10 90.5 0.0 3.0 0.01 1. 1. 1. .9 .8 .9 1. 1. 1. 1.

    A working example data file is part of the program distribution, and can
    be                found                as                gl886rofile.dat
    in  the  source directory.  It contains the data used by Delfosse et al.
    1999 (A&A in press) to derive the orbit of the Gliese 866 very low  mass
    system triple system.


1 VISU
        [ORBIT\]VISU  [/ORBIT i] [/VELOCITY [Component]] [/CORRELATION n]

    Produce a plot of the adjusted orbit and data values, for the radial ve-
    locities, for the visual orbit, or for one coravel-like velocity profile
    at a time.

1 FIT
        [ORBIT\]FIT

    This  command  will perform a least square fit of the adjustable orbital
    elements to the data.

1 FIX
        [ORBIT\]FIX Element [Value [Probable_error]]

    Declare one orbital element as fixed, and optionally set its  value  and
    probable  error. If a value but no probable error is specified a default
    zero probable error is used. See HELP ADJUST for a list of the  elements
    and a concise description of their meaning.

1 ADJUST
        [ORBIT\]ADJUST  Element [Initial_guess] [/ALL] [/SB1] [/SB2] [/VISU-
    AL]

    Declare one orbital element as adjustable, and optionally set its start-
    ing value for the (non-linear) least square fit. If option /ALL is spec-
    ified, all elements become adjustable at once (use FIX if you then  want
    to freeze some of them). Options /SB1, /SB2, and /VISUAL make adjustable
    the elements which can be determined for, respectively,  a  single  line
    spectroscopic  binary,  a double line spectroscopic binary, and a visual
    binary. Supported elements are:

                     P    Period (Days)
                     T0   Epoch of periastron (Julian_days-2400000.0)
                     Ecc  Eccentricity (unitless)
                     as   Semi-major axis (arcseconds)
                     OM   Upper case omega (degrees)
                     w    Lower case omega (degrees)
                     i    Inclination (degrees)
                     K1   Radial velocity amplitude of component A (km/s)
                     K2   Radial velocity amplitude of component B (km/s)
                     V0   Barycenter radial velocity (km/s)
                     W1   Width of first correlation dip  (km/s)
                     W2   Width of second correlation dip (km/s)
                     EW1  Equivalent width of first correlation dip  (km/s)
                     EW2  Equivalent width of second correlation dip (km/s)

    Of those, the last four are only necessary when the  orbit  is  directly
    adjusted  to  CORAVEL-like velocity correlation dips, rather than to the
    resulting extracted velocities.

    For triple and quadruple systems the above elements refer to  the  outer
    orbit. They have the following additional elements to describe the inner
    orbit(s):
                     P1    Period (Days)
                     T01   Epoch of periastron (Julian_days-2400000.0)
                     Ecc1  Eccentricity (unitless)
                     as1   Semi-major axis (arcseconds)
                     OM1   Upper case omega (degrees)
                     w1    Lower case omega (degrees)
                     i1    Inclination (degrees)
                     K11   Radial velocity amplitude of component A (km/s)
                     K12   Radial velocity amplitude of component B (km/s)
    and similarly for an orbit around the secundary of the outer orbit.

1 GLIESE
        [ORBIT\]GLIESE

    Read some  information  (parallax,  position...)  from  the  Gliese  and
    Jahreiss  catalog (version 3.0). This of course can only work for Gliese
    stars, and if you have the Gliese catalog on-line...

1 IGNORE
        [ORBIT\]IGNORE DataType

    Ignore some observational data during the orbit adjustment. DataType can
    be  PARALLAX,  VELOCITY, CORRELATION, or VISUAL. USE has the reverse ac-
    tion.

1 USE
        [ORBIT\]USE DataType

    Use some (previously ignored) observational data during  the  orbit  ad-
    justment.  DataType  can  be PARALLAX, VELOCITY, CORRELATION, or VISUAL.
    IGNORE has the reverse action.

1 LIST
        [ORBIT\]LIST  Information_Type  [/MONTECARLO  [Confidenceel   [Nsam-
    ples]]]  [/OUTPUT Filee] Print some information to the screen. Currently
    supported values are DATA, STATISTICS, ELEMENTS, MASSES, and  EPHEMERID.
    Probable errors are estimated in the linear approximation (good when the
    relative errors are small), unless option  /MONTECARLO  is  present.  In
    this case confidence intervals are listed for each parameter, at the re-
    quested confidence level (default is 0.683, corresponding to 1 sigma for
    normally  distributed  errors).  The number of montecarlo samples can be
    selected, so that each user can make his own tradeoff between  computing
    time  and statistical accuracy (the default is to have 50 points outside
    the confidence interval: 90% confidence will use 500  points,  99%  will
    use 5000, and most likely will take a long time...).

    /OUTPUT can be used to redirect the listing to an external file.
2 DATA
        [ORBIT\]LIST DATA

    Print all data for current star.

2 STATISTICS
        [ORBIT\]LIST STATISTICS

    Print  a  detailed  summary  of the residuals, number of data points and
    Chi2, broken down by data types.

2 EPHEMERID
        [ORBIT\]LIST EPHEMERID [Ndates [Initial_date [Time_step] ] ] /SELECT
    Displayt

    Predict  radial  velocities and relative stellar positions for arbitrary
    dates from current orbital elements. Default parameters are 20 dates, at
    1/20th of a period spacing, and starting at current date.

    Option /SELECT can be used to specify which ephemerid items will be dis-
    played. The default is: Phase, V1, V2, Rho, Theta. It  is  usually  ade-
    quate  for  double  stars,  so this option is most useful when analysing
    triple (or higher multiplicity) systems. Possible values then  addition-
    ally include V11, V12, V21 and V22.

2 ELEMENTS
        [ORBIT\]LIST ELEMENTS [ALL}

    Print current determined orbital elements. If ALL is specified, even un-
    determined elements (for instance the systemic velocity for a purely vi-
    sual orbit) are displayed.

2 MASSES
        [ORBIT\]LIST MASSES

    Print the astrophysical information which can be derived from the avail-
    able orbital elements: mass function(s), "projected masses",  semi-major
    axis in AU, system mass, individual masses, parallax...



1 OPTIMISE
        [ORBIT\]OPTIMISE Parameter /TIME [/SB1] [/SB2] [/XY]
             [/STORE] [/OUTPUT]

    WORK ON THIS COMMAND IS STILL GOING ON...

    Given  an  a priori orbit, optimise the dates of additional observations
    (within a specified time interval) for best accuracy on  one  parameter.
    Existing  measurements  are  taken into account whenever any exist. Sup-
    ported optimisable parameters are MASS_A, MASS_B, MASS_TOT,  and  PARAL-
    LAX. Others (such as any specific orbital element) could easily be added
    upon request.  User input is the length of  the  interval  (starting  at
    current  date  by  default), and the allowed number of measurements with
    their precision for each data type (angular separations and  radial  ve-
    locities).


    The  present  version takes NO observing constraints (below the horizon,
    daytime...) into account. This command will thus mostly be  useful  when
    the  orbital period isn't close to either one year or one day (or if the
    system is circumpolar).

    Option /STORE can be used to append the simulated  optimal  observations
    to  the  current  measurement set (sometimes useful in complex optimisa-
    tion).

    Option /OUTPUT redirects command output to  the specified file.

2 /SB1
        [ORBIT\]OPTIMISE/SB1 Nvels StdErr

    Specifies the number of single line  radial  velocity  measurements  and
    their standard error (in km/s)

2 /SB2
        [ORBIT\]OPTIMISE/SB2 Nsb2 StdErr1 StdErr2

    Specifies the number of double line radial velocity measurements and the
    standard errors for the two components (in km/s)


2 /XY
        [ORBIT\]OPTIMISE/XY Nxy StdErr

    Specifies the number of angular separation measurements and their  stan-
    dard errors (in arcseconds)

2 /TIME
        [ORBIT\]OPTIMISE/TIME Ndays [Starting_MJD]

    Specifies  the  duration (in days) and the starting date (in julian days
    minus 240000, defaulting to current date) of the interval  within  which
    observing dates should be optimised.




1 Language
                        ORBIT\ Language Summary
    ADJUST          : Change status of one parameter to adjustable
    CURSOR          : Call the graphic cursor for interactive data editing
    FIT             : Determine the orbital elements by least square fit
    FIX             : Change status of one parameter to fixed
    GLIESE          : Get some information from the Gliese and Jahreiss catalog
    IGNORE          : Invalidate one type of observational data (see USE)
    LIST            : Print information to terminal screen
    OPTIMISE        : Optimise an observing schedule for a given a priori orbit
    PERIODOGRAM     : Plot a Lomb-Scargle periodogram for the radial velocity data
    READ            : Read a data file
    SAVE            : Save the current data and orbit to a file (usable as input)
    USE             : Validate one type of observational data (see IGNORE)
    VISU            : Draw orbit and data points

1 END

























































