CAL20000 STAR CHART

Effective Year : -9,999~9,999 (20,000 years)
Inquiry period for planet events(trace) : within the effective year range, free version up to 6 months (the Android V26.08 version is free-only). The iOS paid version allows up to 300 years.

This is a lunisolar calendar, ephemeris, and star chart application.
It calculates the accurate positions of the Sun, Moon, and planets on a minute scale, shown on the main month table, the day-detail screen, and the star chart.
The star chart shows star positions from the Bright Star Catalogue and the Milky Way, along with Oriental and Western constellation information.
It shows the Sun/Moon/planet positions at a specific moment on the star chart, and entering a duration in minutes shows their trace over that period.
It calculates solar/lunar eclipses and various planetary events across the entire effective year range, shows the relevant date/time on the day-detail screen, and shows the event's position on the star chart.

## Features

1. The lunisolar, the Gregorian, the Julian day/date, the Islamic/Hebrew month, the sexagenary cycle(干支), 9-star(九星), Kimoon(奇門), 24 solar terms, new moon(with eclipse)/full moon(with eclipse)/first-last quarter/perigee-apogee/ascending-descending node, 28 mansions, Easter date (9-star and Kimoon are only shown for years 1880-2055.)
2. Calculates the Sun/Moon/planet positions and traces and specific events -- conjunction(inferior/superior), opposition, greatest elongation(East/West), quadrature(East/West), perihelion, aphelion, ascending/descending ecliptic node, planet(incl. Moon) conjunction, occultation -- shows the date/time on the day-detail screen and the position on the star chart.
3. Planetary layout, North/South-pole/current-position/Equinox-Equator/Sun-Ecliptic/Galactic-center star charts, each showing the individual Oriental(3-28 mansions) and Western(88) constellations.

## Version History
- V26.08 (Android, Aug 31 2026) : Added iOS V3.5's features to Android
- V3.5 (iOS, Nov 25 2020) : Added Occultation, Moon orbit(白道) star chart. New star chart types (Equinox/Equator, Sun/Ecliptic, Galactic, Oriental 3-28 Mansions, Western 88 Constellations). Added timezone selection.
- V3.0 (iOS, Aug 13 2015) : Added the Milky Way and 110 Messier objects to the star chart
- V2.5 (Android, May 12 2014) : Added Android star chart
- V2.1 (iOS, Apr 2 2014) : Improved star chart query function, extended period
- V2.0 (iOS, Jan 29 2014) : Added iOS star chart
- V1.02 (Android, Oct 24 2012) : Server fix
- V1.01 (Android, Sep 9 2011) : CAL20000 Android first version
- V1.0 (iOS, Sep 6 2011) : CAL20000 iOS first version
- V0.92 (Windows 1998) : Extended the query period from 8192 to 20,000 years, added solar/lunar eclipse calculation
- V0.90 (Windows 1998) : CAL20000 Windows first version

Recent changes:
Version History
- V26.08 (Android, Aug 31 2026): Added iOS V3.5's features to Android
- V3.5 (iOS, Nov 25 2020): Added Occultation & Moon-orbit star chart, new chart types (Equinox/Equator, Sun/Ecliptic, Galactic, Oriental/Western constellations), and timezone selection.
- V3.0 (iOS, Aug 13 2015): Added the Milky Way and 110 Messier objects to the star chart
- V2.5 (Android, May 12 2014): Added Android star chart
- V2.1 (iOS, Apr 2 2014): Improved star chart query function, extended period