export declare class TrueSolarTimeCalculator {
    private readonly _initialUtcDate;
    private readonly _longitude;
    private readonly _latitude;
    private _julianDay;
    private _equationOfTimeSeconds;
    private _trueSolarTime;
    /**
     * Creates an instance of the calculator.
     * @param inputDate The input Date object. Assumed to represent a moment in UTC.
     * @param longitude Observer's longitude in degrees (-180 to 180, positive East).
     * @param latitude Observer's latitude in degrees (-90 to 90, positive North).
     */
    constructor(inputDate: Date, longitude: number, latitude: number);
    /** Gets a copy of the initial UTC Date used for calculations. */
    get utcDate(): Date;
    /** Gets the observer's longitude. */
    get longitude(): number;
    /** Gets the observer's latitude. */
    get latitude(): number;
    /**
     * Calculates and returns the Julian Day (JD) based on the initial UTC date.
     * JD is the number of days since noon Universal Time (UT) on January 1, 4713 BCE.
     */
    get julianDay(): number;
    /**
     * Calculates and returns the Equation of Time (EoT) in seconds.
     * EoT is the difference between apparent solar time and mean solar time.
     * Positive EoT means the Sun is "fast" (transits before mean noon).
     * Negative EoT means the Sun is "slow" (transits after mean noon).
     * This uses a common approximation formula.
     */
    get equationOfTimeSeconds(): number;
    /**
     * Gets the day of the year (1-366) for the initial UTC date.
     */
    get dayOfYear(): number;
    /**
     * Calculates the True Solar Time (TST) and stores it internally.
     * Returns the calculator instance for method chaining.
     */
    calculateTrueSolarTime(): this;
    /**
     * Returns the calculated True Solar Time as a new Date object.
     * Ensures TST is calculated if it hasn't been already.
     */
    getDate(): Date;
    /**
     * Formats the calculated True Solar Time Date object into a string.
     * @param formatString A format string (e.g., 'YYYY-MM-DD HH:mm:ss'). Default is 'YYYY-MM-DD HH:mm:ss'.
     *                     Supports YYYY, MM, DD, HH, mm, ss placeholders.
     * @returns The formatted date string.
     */
    format(formatString?: string): string;
    /**
     * Returns the Equation of Time in a human-readable format (e.g., "X分Y秒").
     */
    getHumanReadableEOT(): string;
    /**
     * Returns the calculated True Solar Time as a string in HH:mm:ss format.
     */
    getTrueSolarTimeString(): string;
}