Software for astronomy, calendars and date conversion

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Easy Date Converter 12.26 Click on the title for the full description US$17.95, €14.75 or £13.25 for a perpetual license or US$5.95, €4.95 or £4.45 for a 3-month license
Adds a number of days or months to a date, calculates the number of days between two dates (with or without weekend days), and converts among Common Era (Gregorian) dates, Julian dates, ISO 8601 Week dates, Hermetic Leap Week dates, Julian day numbers and day-in-year dates of the form yyyy-ddd. Bilingual: English and German   Top

Julian‑Gregorian‑Dee Date Calculator 7.54 Click on the title for the full description US$17.95, €14.75 or £13.25 for a perpetual license or US$5.95, €4.95 or £4.45 for a 3-month license
Converts between Julian, Gregorian, Dee and Dee-Cecil calendar dates in various formats, adds/subtracts a number of days, weeks, months and years to/from a given date, and calculates northern spring equinoxes using either mean or apparent solar time.   Top

Chinese Calendrics 16.16 Click on the title for the full description US$35.95, €29.45 or £26.25 for a perpetual license or US$11.95, €9.75 or £8.75 for a 3-month license
A program to convert between dates in various Chinese calendars and dates in the Gregorian and Julian calendars, and to find (among other things) lunar new year's day and leap months for any year in the Chinese Calendar.   Top

Lunar Calendars and Eclipse Finder 16.36 Click on the title for the full description US$17.95, €14.75 or £13.25 for a perpetual license or US$5.95, €4.95 or £4.45 for a 3-month license
A program to search for eclipses (lunar, solar, total, annular and partial), to calculate the phase of the Moon at any given date and time and to convert between dates in the Gregorian and Julian calendars and dates in various lunar calendars: Meyer-Palmen Solilunar, Hermetic Lunar Week, etc.   Top

Celtic Festivals and Cross Quarter Days 9.44 Click on the title for the full description US$29.95, €24.75 or £21.95 for a perpetual license or US$9.95, €8.25 or £7.25 for a 3-month license
A program to find the exact dates and times, and zodiac positions, of full moons and dark moons, lunar Celtic festivals (Imbolc, Beltane, Lughnasadh and Samhain), equinoxes and solstices, and solar cross-quarter days. Moreover, it can do this for any range of years between 1600 and 2099.

Date‑Time Calculator 6.04 Click on the title for the full description US$23.95, €19.75 or £17.45 for a perpetual license or US$7.95, €6.45 or £5.75 for a 3-month license
Software to perform conversion, addition and subtraction of dates and times.   Top

Eclipses, Moon Phases and Seasons 8.14 Click on the title for the full description US$29.95, €24.75 or £21.95 for a perpetual license or US$9.95, €8.25 or £7.25 for a 3-month license
Displays (over a range of years) the exact dates and times of partial, annular and total solar eclipses, of partial, penumbral and total lunar eclipses, of phases of the Moon, and of solstices, equinoxes and the solar cross-quarter days.   Top

Equinoxes, Solstices and Cross‑Quarter Days 6.17 Click on the title for the full description US$11.95, €9.75 or £8.75 for a perpetual license or US$3.95, €3.25 or £2.95 for a 3-month license
Software to calculate accurate dates and times for equinoxes, solstices and the Celtic cross-quarter days. The cross-quarter days are those midway between the equinoxes and solstices. Works for both the northern hemisphere and the southern.   Top

These programs run under all versions of Windows from Windows XP to Windows 10. The freely downloadable trial versions can be made fully-functional by means of an activation key available after purchase of a user license. Updates to new versions (if any) are free, as is tech support for the duration of the user license.
 

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