Is this flight software?

No. SIDUS models are educational reimplementations. Cross-check before any flight decision.

Coelliptic drift

Relative mean motion from Δa and time to gain phase (rendezvous coelliptic ops).

SIDUS educational calculator. Category orbital. Tags: GNC, operations, orbital, relative-motion, rendezvous. Pure SI. Not flight software.

n_rel ≈ −(3/2) n (Δa/a)

Coelliptic relative drift

Fundamentals of Astrodynamics and Applications (David A. Vallado): Standard reference for two-body, Lambert, maneuvers, and J2. Equations implemented independently in SIDUS.
Orbital Mechanics for Engineering Students (Howard D. Curtis): Textbook derivations for Hohmann, vis-viva, rocket equation, elements.
Spaceflight Dynamics (William E. Wiesel): Relative motion, rendezvous, and phasing context complementary to Vallado/Curtis.

Read /llms.txt or call https://sidus.tools/api/mcp. Open the interactive page for live SI inputs.