Candidate Identifier beta
Which cataloged object is your satellite? Compare a set of candidate NORAD objects from the same launch: current orbital elements, automatic drag-family grouping, and element evolution since deployment.
Enter the NORAD catalog IDs of the candidate objects (typically all objects cataloged from one launch).
Example: ?ids=69897,69941,100100,69905,69910
Current elements & drag families
| Fam | NORAD | Name | Mean motion rev/day | Perigee km | Apogee km | Ecc | Incl deg | B* | Epoch age h | TLEs |
|---|
Drag signature: perigee altitude vs B* (log scale). Objects cluster into drag families — family membership is usually more robust than any ranking within a family.
Along-track separation
Signed along-track offset relative to the reference object (positive = leading). Positions use the element set nearest to the displayed time, not the latest one. The shaded era predates the first available element set — geometry there is backward extrapolation and unreliable for ordering claims.
Candidates only, live positions. Dot colors do not yet match family colors.
Element history
Each dot is a published element set (epoch marker). Circularization, differential drag fan-out and maneuver kinks are visible here before they show in single-epoch comparisons. Element values are SGP4 mean elements — do not compare them field-by-field against operator OPM/osculating elements.
Pass planner
| Object | AOS UTC | Dur min | Max El | AOS→LOS Az | Session |
|---|
A “pair session” marks passes of same-family objects close enough in time (overlap or gap under 15 min) to cover with one antenna session — families are dynamically near-identical, so test them together. Predictions use each object's latest element set; along-track error grows with element-set age. Click a pass row to open it in the Doppler discriminator below.
Doppler discriminator
Predicted received-frequency offset for every candidate over the selected pass window. One S-curve will match a real recording; near-identical family pairs produce near-overlapping curves — such passes cannot discriminate within the pair.
OPM correlator
Position residual between the OPM state (numerically propagated, two-body + J2, no drag) and each candidate's SGP4 trajectory, compared as Cartesian states at common epochs — never element-by-element. All residuals grow with time because the OPM propagation carries no drag; weight the early, shaded-era-adjacent samples most. Ranking is the median residual over the cataloged era.