WINDOWS · MPC OBS80 · FIND_ORB
From observations to an orbit you can inspect.
A Windows workspace for orbit determination, residual analysis and observing plans. A familiar compact layout brings Bill Gray’s Find_Orb calculation source together with station context, ephemerides and interactive sky views.
Version 0.1.29
OBS80 / RES. / Δt / PA
Keep the observation in sight.
Inspect the complete 80-column observation beside signed RA/Dec residuals, time-shift diagnostics and station notes. Refine the solution, choose an observing site and follow its predicted path across the sky.
01 — 06
One observation set. A traceable workflow.
- 01
Open… and MPC…
Open… reads OBS80, ADES PSV and ADES XML using Bill Gray’s source converter. Unrelated lines are silently ignored. If no observations are recognised, your existing observations, orbit and ephemerides remain available.
- 02
Orbit methods and stopping
Herget step uses the R1 and R2 distance estimates in AU. Full step refines the current fit once; Auto-Solve runs five full steps. Simplex offers another improvement method. Gauss searches suitable short arcs and alternative roots, scores candidates against all included observations and produces an initial orbit. Follow Gauss with Full step rather than treating a starting solution as a finished fit.
- 03
Read positional residuals
res. RA and res. Dec are the signed east/north positional differences reported for the fit; res. total is their combined angular size. They are offsets on the sky, not the absolute right ascension or declination. Compare both components: a small total alone cannot identify a timing pattern, catalogue bias or a station-specific offset. PA is the residual direction measured from north through east, in degrees.
- 04
Start, clock, end time and Steps
The Start row has a date picker, a separate clock including seconds and Local / UTC / Zone…. Local uses the computer’s time zone; Zone… chooses an observatory time zone. All inputs are converted to UTC for the core. Now fills the current instant in the chosen zone. Missing or ambiguous local times at a daylight-saving transition require an unambiguous UTC selection.
- 05
Star chart: atlas, zoom and labels
Star chart draws a star-atlas view with ephemeris points, equal sky scaling and sexagesimal RA/Dec ticks. Right ascension is labelled in hours, minutes and seconds; declination in degrees, arcminutes and arcseconds. A bright-star atlas, constellation lines and the Milky Way give wide-field context; Gaia DR3 adds faint stars for narrow fields when available. The brightest field star has a 10-pixel symbol, with smaller symbols for fainter magnitudes and a whole-magnitude legend.
- 06
Pseudo-MPEC: a local circular
Pseudo-MPEC opens a text window with observations, observer details, orbital elements, arcsecond residuals and the run’s ephemeris when present. The layout follows an MPEC, including vertically filled residual columns and parentheses for excluded positions. Every station in the archived observation snapshot remains represented, even when telescope details are unknown.
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Real calculations, visible context.
Real calculation views and interface examples from local runs. The main-window image is a captured OrbitWorkbench 0.1.11 session. Other examples render the application’s interface components built from source with calculated data; they are not evidence of a complete visible click test of the signed executable.
A local application with a source-based core.
OrbitWorkbench is a Windows application by Jost Jahn based on Bill Gray’s Find_Orb source. The Downloads page provides the signed installer, portable package and corresponding GNU GPL source code. Astronomy data are downloaded separately from their providers.
Detailed help →