☰ Double Star Calculator - Orbit Determination

The Double Star Calculator – Orbit Determination processes historical measurements of the separation and position angle of a double star and attempts to determine its orbital elements.

Simply press the [SUBMIT DATA] button to see how the tool works with the provided default data. Use [CLEAR ALL] to empty all input fields and prepare for new data, or click [RESTORE DEFAULT] to reload the default data. The Measurement Data field is mandatory; use [CLEAR] to empty this field.

The Measurement Error fields are optional global error parameters used in the calculation of the orbital elements if measurement errors are not available in the Measurement Data field. The Initialization section allows selection of the type of initialization (Simple, Thiele-Innes, or Orbital Elements). Verbose controls the level of detail in the returned results, and Seeds defines the number of different random seeds used in the orbit calculation.

The WDS Discoverer, Observation Epoch, and Start/End Epoch parameters are also optional and, if provided, will be used in the generated report and diagrams. Unless the Start/End Epoch parameters are set manually, the start and end epochs are automatically calculated based on the determined orbital period.

The parameter section Initialization with Orbital Elements is enabled when the initialization type is set to Orbital Elements. In this case, the entered orbital elements are used as an initial guess for the orbit determination. This can be useful, for example, for refining an existing orbital solution.

Notes: A detailed description of the Double Star Calculator is available in the Double Star Calculations Help - Orbit Determination.

The format of the mandatory Measurement Data follows the WDS OBSERVATION CATALOG: data line format, Version 5, from February 2025. The actual measurements have to start on line #12. Line and column numbering starts with '1':


Measurment Data - Expected Fixed-Width Format
Columns Parameter Example
Col 008–017 Epoch/date (f10.5) 1995.2410
Col 020–026 Position Angle/theta θ (°) 142.500
Col 028–033 θ Error/terr (°) [optional] 0.500
Col 036–044 Separation ρ/rho (″) 1.23400
Col 047–053 ρ Error/rerr (″) [optional] 0.02000
Col 112–113 Technique Code/tech [optional] Su (USNO speckle (ICCD))

Measurement Data (Mandatory)
Optional Arguments
ρ error
(± arcseconds)		 θ error
(± degree)
Initialization Verbose Seeds
WDS Discoverer Observation Date Start Epoch End Epoch

Please be patient. Depending on the configuration and the number of measurements, processing may take anywhere from a few seconds to over a minute.

Initialization with Orbital Elements