CAL20000 진짜萬歲曆 USER GUIDE Introduction
This calendar is made based on the calcuation of accurate sun and moon position. The effective year range is from -10000 to 10000. You can download this program or view web page by making selection on the left menu.
Version Information
V0.91 : Initial Version 1998 V0.92 : 1998.November 5 V0.93 : 1999.september.11 V0.94 : 2000.November.8 V0.95 : 2008.December.18
V1.00 : 2011.August
NOTICE
* Please be aware of that the day information on this calendar and historic calendar can be difference because of many reason.
This calendar just make calcuation and show only based on the material of present astronomy and physics.
But calcuation value can have some error range and be difference to the true value.
And historic data was determined based on the material of the past. As the present value is more close to true value than the past value,
but the past day was determined at the past time and the day information can not be changed now. * There is no year 0 in historic calendar. People use year BC 1 instead of year 0. the previous year of year 1(=AD 1) is BC 1. However, there is year 0 in this calendar because it use scientific numbering system. If you want to see year BC 5, you shall use year -4. And So on. * The display method of this calendar is just only the Gregorian calendar. If you want to know Julian calendar date, you have to adjust below value to day which is difference between Julian and Gregorian. After March AD 4       -2 day       After March AD 900 5 day Befor AD 4, The historic date is not compatible to Julian calendar because the date was controled by the Roman Emperor's own will. However, The Western use the uniform Julian calendar for astronomic purpose. So you are also needed to adjust -1 day for every 100 year for before AD 4. * Lunar first day error The lunar first day of a month is determined by the exact time of new moon.
If the time is around the midnight, It is very difficult to determine which day is the first day.
For example, if the time of new moon is 23:59, the day of before midnight is lunar first day,
and if the time is 00:00, the day of after midnight is lunar first day. Just one minute difference make one day difference.
At present, as we can calculate and estimate a future new moon time with very high accurate, but it is not enough accruate to make determine a right lunar first day.
(Furure, If someone make more accurate equation than present, the new moon time will can be changed and lunar first day also will can be changed) * Lunar intercalary month error Lunar intercalary month is determined by the exact time of new moon and the exact time of mid term of the 24 solar term.
So, it is also applyed lunar first day error to the same 24 solor term error and to determine a intercalary month.
This error make that a intercalary month move with in 3 month front or rear to real intercalary month.
If there is a intercalary month of a specific year on CAL20000, there must be exist the intercalary month on historic calendar with in 3 month.
It is very useful to use with sexagenary day number(日辰) for confirm a lunar date or intercalary month. EPOHCH & Calcuation Method
The epoch of the calcuation for the 24 solar term is 22:08 Feb 4, 1996(丙子年 立春) and a tropical year length is 365.2423611 days(=365 day 5hour
49min=525949 mininute) The 24 solor terms are calculated by my own method.(Strictly speaking, I follow traditional calcuation method of Korean/Chinese calendar). The new/full moon time are calculated according as the sun table equation of Newcomb's and the moon table equation of Brown's which are based on theory of the present astronomy with my own algorithm. You can see the initial my own algorithm from the Delphi & Perl source on the left menu. Error Range
The Gregorian Calendar have one day error for 3300 years, CAL20000 have almost no error. The precise error range is here. New moon day and 24 solor term day is changed when it is around midnight(When is 23:59 and 00:00). This make the shift of lunar month day and intercalary month. ----------------------- At that time(1998), I thought that above error range was applied to all effective year(-10000~10000). At present(mid 2011), I have a reference to campare CAL20000 value with. It is NASA eclipse site data. The solor eclipse exact time which was occurced Julian day 991085 (CAL20000 - Gregroian date -1999.5.25, NASA Eclipse site - Julina Date is -1999.July.12), is that the JD number of NASA is 991085.63500, and the JD nubmer of CAL20000 is 991085.482638889. The difference is 0.152361111 day(=991085.63500-991085.482638889), this is about 219 minutes equal to 3 hours 40min.
There is 3hour 40min error on moon posion for 5000 year ago between NASA value and CAL20000 value.
I have confidence with evidence data which are based on Korean/Chinese historic record that my calcuation result is far more close to real value than the value from the theory of the present astronomy.
MISCELLANEOUS
- A lunar month name and intercalary month problem when is occured a lunar month include two mid term around the perihelion is corrected by resonable method. - The reference books are the principle of calendars(曆法의 原理分析 written by EunSung Lee, Korean book), Almanacs(1988, 1990 1992, 1993, 1996, 1997,1998) printed by the Korea Astronomy and space science institute. - The solor eclipse records on Spring and Autumn Annals(春秋) and Korean history annals for three nation(三國史記) are meet to the value of CAL20000. You also can see these eclipse on the historic records at CAL20000 as you check with sexagenary day number(日辰) which are on the historic records. Also the solor eclipse which was predicted but could not see at Korea on korean historic record had been occured at south america. - The information about this CAL20000 program or lunar calendar are on my hompage http://user.chollian.net/~kohyc/calendar and my email address is kohyc@chol.com (Please mail to me with Korean or English only, I don't know other language and I am not good at English) - It is very helpful to let me know if CAL20000 program has any error. - USAGE Just enter Year(-10000~10000) and month(1~12). then the information for the month will be displayed. The information values are only Gregorian date value. - Displayed information If you click day cell, then the detailed information for the day is displayed. (Web version do not suppport this function because the informations are displayed below month table.) The every time information on CAL20000 is the local time of Seoul (East 135degree, GMT+9). 2011年 8月 1日
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