/**
 * ayanamsa.ts — Sidereal zero-point models (Drik Siddhanta).
 *
 * Two families of ayanamsa live here, and the distinction matters:
 *
 *   • **Star-defined ("true") ayanamsas** — the zero point is fixed by putting a
 *     named star at an exact sidereal longitude. True Chitrapaksha is the
 *     canonical case: Chitra (Spica, α Virginis) sits at exactly 180°00′00″.
 *     These need no fitted constants at all. The ayanamsa is *derived* from the
 *     star's computed position, so it is exact by construction at every date
 *     and tracks the real sky (Drik / observational siddhanta).
 *
 *   • **Epoch-defined ayanamsas** — the zero point is fixed by declaring a value
 *     at a reference epoch (Lahiri, Raman, KP, Fagan/Bradley …). These need an
 *     (epoch, value) anchor and are then propagated by precession.
 *
 * ── What changed and why ─────────────────────────────────────────────────────
 * The previous version modelled *every* ayanamsa as a J2000 constant plus the
 * scalar polynomial ψ_A = 5029.0966″T + 1.1120″T². Two problems:
 *
 *   1. Precession of the sidereal zero point is a rotation of the ecliptic
 *      frame, not a scalar added to a longitude. The shortcut drifts.
 *   2. The J2000 constants were back-fitted so that one chart reproduced one
 *      expected Moon longitude. Any error elsewhere in the engine (and there
 *      was 7–41″ of it) got absorbed into those constants, then re-emitted at
 *      every other date.
 *
 * Both families are now propagated with the exact IAU 2006 precession rotation
 * from `precession.ts`, and the true-star family carries no fitted constant.
 */
import { type Vec } from './precession.js';
/**
 * ICRS astrometry, matching the entries Swiss Ephemeris ships in `sefstars.txt`
 * so that star-defined ayanamsas agree with SE/JHora rather than drifting by
 * the ~1 mas/yr difference between Hipparcos reductions.
 */
export interface StarData {
    name: string;
    /** Right ascension at J2000, degrees (ICRS). */
    ra: number;
    /** Declination at J2000, degrees (ICRS). */
    dec: number;
    /** Proper motion in RA, μα·cos δ, mas/yr. */
    pmRA: number;
    /** Proper motion in declination, mas/yr. */
    pmDec: number;
    /** Parallax, mas. */
    parallax: number;
    /** Radial velocity, km/s. */
    radVel: number;
}
export declare const STARS: Record<string, StarData>;
/**
 * Longitude of a fixed star in the **mean ecliptic and equinox of date**,
 * in degrees.
 *
 * Applies space motion (proper motion + radial velocity) and, optionally,
 * annual parallax. Nutation is excluded by definition — ayanamsa is referred to
 * the mean equinox. Annual aberration is excluded by default: including it
 * would make the ayanamsa oscillate by ±20″ over each year, which is not how
 * panchanga ayanamsa is tabulated.
 *
 * @param star        Catalogue entry
 * @param jdUT        Julian Day, UT
 * @param observerAU  Optional observer barycentric position (AU, ICRF) for parallax
 */
export declare function starLongitudeOfDate(star: StarData, jdUT: number, observerAU?: Vec): number;
/** A star-defined ("true") ayanamsa: `star` sits at exactly `atLongitude`. */
interface StarModel {
    kind: 'star';
    star: keyof typeof STARS;
    /** Sidereal longitude the star is pinned to, degrees. */
    atLongitude: number;
    label: string;
}
/** An epoch-defined ayanamsa: `value` degrees at Julian Day `jd`. */
interface EpochModel {
    kind: 'epoch';
    jd: number;
    value: number;
    label: string;
    /** Where the anchor came from — see AYANAMSA_MODELS for the provenance rules. */
    source: 'definition' | 'jhora' | 'provisional';
}
export type AyanamsaModel = StarModel | EpochModel;
/**
 * Swiss Ephemeris `SE_SIDM_*` mode number → model.
 *
 * `source` records where each epoch anchor comes from:
 *
 *   'definition'  — the published definition of the ayanamsa itself.
 *   'provisional' — best available anchor, not yet checked against JHora. Treat
 *                   these as approximate; they may be off by arcminutes.
 *
 * Star-defined entries need no anchor at all and are exact by construction —
 * prefer them. True Chitrapaksha (27) is the project default and is verified
 * against JHora to 0.015″; True Pushya (29) is verified to 0.03″.
 *
 * ── A caution, from experience ──────────────────────────────────────────────
 * An earlier revision carried a mode-1 anchor of 23.926408° at the 1998 chart,
 * described as a JHora reading showing that "JHora's Lahiri sits 4.78′ above the
 * ICRC definition". That was wrong. The figure came from a corrupted transcript
 * whose ayanamsa was 6′ too high and whose planets were correspondingly 6′ too
 * low — the signature of numbers generated from a bad ayanamsa rather than read
 * off a screen. Actual JHora output for that chart reads 23°49′35.07″, which is
 * True Chitrapaksha, and matches this engine to 0.015″.
 *
 * The lesson: an ayanamsa anchor is only as good as the provenance of the single
 * number behind it. Anchor to a published definition, or to a star; do not
 * anchor to a reading you cannot re-verify.
 */
export declare const AYANAMSA_MODELS: Record<number, AyanamsaModel>;
/** Human-readable name for a mode, for logs and API responses. */
export declare function ayanamsaName(mode: number): string;
/**
 * Longitude, in the mean ecliptic of date `jdTo`, of the vernal point that was
 * the equinox at `jdFrom`. This is the accumulated general precession between
 * the two epochs, computed as an exact frame rotation rather than a polynomial.
 *
 * Returned in (−180, 180] so that epochs before `jdFrom` give negative values.
 */
export declare function accumulatedPrecession(jdFrom: number, jdTo: number): number;
/**
 * Ayanamsa in degrees for a given SE mode and Julian Day (UT).
 *
 * @param mode  Swiss Ephemeris SE_SIDM_* code (27 = True Chitrapaksha)
 * @param jd    Julian Day, UT
 */
export declare function getAyanamsa(mode: number, jd: number): number;
/**
 * Mean longitude of the Moon's ascending node (Rahu), tropical degrees,
 * referred to the mean ecliptic of date.
 *
 * Meeus, *Astronomical Algorithms* eq. 47.7 — four terms rather than the
 * previous three, which drifted at the 0.001° level over the DE440s span.
 *
 * @param T  Julian centuries (TT) from J2000.0
 */
export declare function meanLunarNode(T: number): number;
/** Convert a tropical longitude to sidereal by subtracting the ayanamsa. */
export declare function toSidereal(tropical: number, ayanamsa: number): number;
export {};