import { JulianDays } from "./common";
import { HistoricalDate } from './historical-date';
import { GregorianDate } from "./gregorian-date";
export declare class JulianDate extends HistoricalDate {
    readonly year: number | undefined;
    readonly month: number | undefined;
    readonly day: number | undefined;
    readonly isLeapYear: boolean;
    constructor(year: number | undefined, month: number | undefined, day: number | undefined);
    /**
     * Creates a new JulianDate object based on the number of Julian days.
     */
    static fromJulianDays(jd: JulianDays): JulianDate;
    static fromString(text: string): JulianDate;
    /**
     * Check if this is a legal date in the Julian calendar
     */
    private assertLegalDate;
    /**
     * Convert to Julian day using astronomical years (0 = 1 BC, -1 = 2 BC)
     */
    private toJulianDays;
    private monthLength;
    addDays(days: number): JulianDate;
    toGregorian(): GregorianDate;
    toJulian(): this;
    toString(): string;
}