Safeguarded Kepler root solving and observation uncertainty
Research context
research method · conditional · As of 2026-10-10
For an elliptic orbit, d(E-e sin E)/dE is positive, so the root is unique for a chosen unwrapped mean anomaly.
Key knowledge
For an elliptic orbit, d(E-e sin E)/dE is positive, so the root is unique for a chosen unwrapped mean anomaly. Newton steps can be safeguarded in [M-e,M+e]; monotonicity supplies that bracket directly. Small residuals establish numerical accuracy, not orbital-parameter accuracy.
Values and equations
E_next=E-(E-e sin E-M)/(1-e cos E); 1-e cos E ≥ 1-e >0
- E,E_next,M
- Anomalies in one unwrapped branch rad
- e
- Elliptic eccentricity 1
Conditions and scope
- The bracket is a mathematical consequence of |sin E|≤1, added explicitly to JPL's Newton iteration.
- Near e=1 the derivative can be small; preserve unwrapped branches and propagate fitted element/time covariance into observables.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Approximate positions of the planets: Orbital-plane coordinates, time range and iterative Kepler equation (selected source body inspected).
2026-10-10 · Bounded source check of the recorded statement and conditions. This does not certify a unique physical model, reproduce the cited study or replace independent branch review.
Entry details
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- research-earth-kepler-solve
- Revision
- research.1
- Structured reference record
- Postgraduate & research reference