/**
 * coordinates.ts — Julian day, sidereal time, angles and house cusps.
 *
 * Frame transforms (precession, obliquity) now live in `precession.ts`, and the
 * apparent-place chain (light-time, aberration, deflection) in `apparent.ts`.
 * What remains here is the Earth-rotation side of the problem: sidereal time,
 * the ascendant/MC, house cusps, and the observer's geocentric vector.
 *
 * All angles are in degrees unless documented otherwise.
 */
import { meanObliquity, julianCenturies, type Vec } from './precession.js';
export { meanObliquity, julianCenturies };
/** Reduce an angle to [0, 360). */
export declare function mod360(x: number): number;
/**
 * Julian Day Number (UT) from a UTC calendar date (Meeus §7, Gregorian).
 */
export declare function julday(year: number, month: number, day: number, hourUT: number): number;
/**
 * Greenwich Mean Sidereal Time in degrees, IAU 1982 (Aoki et al.).
 *
 * UTC is used in place of UT1. |UT1 − UTC| ≤ 0.9 s, which is ~13″ of Earth
 * rotation — the dominant uncertainty in the ascendant. Swiss Ephemeris (and
 * therefore JHora) makes the same substitution, so this matches rather than
 * diverges from the reference.
 */
export declare function getGMST(jdUT: number): number;
/**
 * Greenwich Apparent Sidereal Time in degrees: GMST plus the equation of the
 * equinoxes (Δψ · cos ε_true).
 */
export declare function getGAST(jdUT: number): number;
/** True obliquity of the ecliptic (mean + nutation in obliquity), degrees. */
export declare function trueObliquity(jdUT: number): number;
/**
 * Observer position and velocity relative to the geocentre, expressed as an
 * ICRF equatorial vector in km and km/s.
 *
 * This replaces the previous ad-hoc lunar-parallax formula. Adding the true
 * observer vector to Earth's barycentric state means light-time, aberration
 * (including the diurnal component) and parallax all fall out of the same
 * apparent-place chain instead of being patched on afterwards.
 *
 * @param jdUT      Julian Day, UT
 * @param latDeg    Geodetic latitude, degrees
 * @param lonDeg    Geographic longitude, degrees east
 * @param altitudeM Height above the ellipsoid, metres
 */
export declare function observerGeocentricVector(jdUT: number, latDeg: number, lonDeg: number, altitudeM?: number): {
    position: Vec;
    velocity: Vec;
};
/**
 * Tropical Ascendant from RAMC and geographic latitude.
 *
 * ASC = atan2( cos(RAMC),  −(sin ε · tan φ + cos ε · sin RAMC) )
 *
 * The two-argument form resolves the quadrant directly. A single-argument
 * atan collapses the result into ±90° and needs sign patching that fails for
 * roughly half the zodiac — the source of the historical 180° ascendant bug.
 *
 * @param ramc  Right ascension of the midheaven, degrees
 * @param lat   Geographic latitude, degrees
 * @param eps   Obliquity of the ecliptic, degrees
 */
export declare function computeAscendant(ramc: number, lat: number, eps: number): number;
/** Tropical Midheaven from RAMC. */
export declare function computeMC(ramc: number, eps: number): number;
/**
 * Tropical Vertex — the ecliptic point on the prime vertical due west.
 * Equivalent to the ascendant computed for the co-latitude, half a turn away.
 */
export declare function computeVertex(ramc: number, lat: number, eps: number): number;
/**
 * Whole-Sign house cusps from the sidereal ascendant: house 1 begins at 0° of
 * the sign holding the ascendant, and each subsequent house is the next sign.
 */
export declare function wholeSignCusps(ascSidereal: number): number[];
/**
 * Equal-house cusps: 30° arcs measured from the exact ascendant degree.
 */
export declare function equalHouseCusps(ascSidereal: number): number[];