/**
 * apparent.ts — Geometric ephemeris state → apparent place.
 *
 * Turns raw DE440 barycentric vectors into the direction an observer actually
 * sees, applying, in the order the corrections physically occur:
 *
 *   1. Light-time    — the body is seen where it *was* when the light left it.
 *                      Solved iteratively; the observer stays at epoch t.
 *   2. Deflection    — solar gravity bends the ray (≤1.75″ at the solar limb,
 *                      ~0.004″ at 90° elongation).
 *   3. Aberration    — the observer's barycentric velocity tilts the apparent
 *                      direction by up to 20.5″.
 *
 * The previous implementation had none of these working: light-time was
 * computed in *days* and then subtracted from an epoch expressed in *seconds*,
 * so the correction was ~86400× too small and effectively absent, and neither
 * aberration nor deflection existed at all. Together those accounted for most
 * of the 7–41″ error measured against JPL Horizons.
 *
 * Output is an ICRF equatorial unit vector plus true geometric distance; the
 * caller rotates it into whichever ecliptic frame it needs.
 */
import type { Vec3 } from './chebyshev.js';
import type { Vec } from './precession.js';
/** Astronomical unit, km (IAU 2012). */
export declare const AU_KM = 149597870.7;
/** Minimal slice of SpkFile that this module needs. */
export interface BarycentricSource {
    getBarycentric(naifBody: number, et: number): Vec3;
}
export interface ApparentPlace {
    /** Apparent direction as an ICRF equatorial unit vector. */
    direction: Vec;
    /** Geometric distance observer → body at emission, in AU. */
    distanceAU: number;
    /** Light-time in seconds. */
    lightTimeSec: number;
}
export interface ObserverState {
    /** Barycentric position, km (ICRF equatorial). */
    position: Vec;
    /** Barycentric velocity, km/s (ICRF equatorial). */
    velocity: Vec;
}
/**
 * Which of the three corrections to apply.
 *
 * Astronomy defaults to all three ("apparent place" — where a telescope points).
 * Jyotish software conventionally does not: JHora publishes **geometric** places,
 * with all three off. Measured against JHora's 1998 reference chart, the gap
 * between the two conventions is 44″ for Venus, 21″ for the Sun and 7″ for
 * Saturn — small, but far above the arcsecond level this engine works at, so it
 * has to be an explicit choice rather than an assumption.
 */
export interface PlaceCorrections {
    lightTime?: boolean;
    deflection?: boolean;
    aberration?: boolean;
}
/** Geometric place: where the body *is*, ignoring how its light reaches us. */
export declare const GEOMETRIC: Required<PlaceCorrections>;
/** Apparent place: where the body is *seen*. Matches JPL Horizons. */
export declare const APPARENT: Required<PlaceCorrections>;
/**
 * Barycentric state of the observer.
 *
 * @param geocentreOffset Optional observer offset from the geocentre in km
 *                        (ICRF equatorial) for topocentric places, plus its
 *                        velocity in km/s from Earth rotation.
 */
export declare function observerState(spk: BarycentricSource, earthNaifId: number, et: number, geocentreOffset?: {
    position: Vec;
    velocity: Vec;
}): ObserverState;
/**
 * Geocentric (or topocentric) place of a solar-system body.
 *
 * @param spk         Barycentric state source (the loaded SPK file)
 * @param naifBody    NAIF id of the target
 * @param sunNaifId   NAIF id of the Sun (for the deflection geometry)
 * @param et          Ephemeris time, seconds past J2000.0 TDB
 * @param observer    Observer barycentric state at `et`
 * @param corrections Which corrections to apply; see {@link PlaceCorrections}
 */
export declare function computePlace(spk: BarycentricSource, naifBody: number, sunNaifId: number, et: number, observer: ObserverState, corrections?: Required<PlaceCorrections>): ApparentPlace;