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Chen Wei
2014-03-11 10:54:40 +08:00
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README.md
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@@ -7,26 +7,25 @@ Chinese Lunar Calendar for use with online and offline calendar apps.
The Chinese Lunar Calender is mostly based on the motion of the Moon. It is
said due to the complicate interaction, mostly from the Sun and the Earth, the
motion of Moon is very hard to predict, especially on the long run. Luckily
[Hong Kong Observatory][HK_Obs] has published a convertion table for the period
[Hong Kong Observatory][HK_Obs] has published a conversion table for the period
from 1901 to 2100. It is the most trustworthy Lunar Calender I can find on the
web so far.
Lunar calendar beyond 1901-2100 range can also be generated. The
lunarcalbase.py uses VSOP87 planetary theory and LEA-406 lunar theory to
find solar terms and moon phases, then compute the calendar.
Lunar calendar beyond 1901-2100 range is generated by finding solar terms and
moon phases uses [VSOP87 planetary theory][]and [LEA-406 lunar theory][].
Both the full version and truncated version of LEA-406 and VSOP87 are included.
The full version is slightly slower. Their accuracy of finding apparent Sun and
Moon longitude compare to the DE431 based JPL Horizon are showed in following
figures.
The full version of LEA-406 and VSOP87 are used by default. A truncated version
, aa.py, also included. The full version is slightly slower than the truncated
version. Their accuracy of finding apparent Sun and Moon longitude compare to
the DE431 based JPL Horizon are showed in following figures.
![aa_full][]
![aa_trunc][]
For the time span from 1949 to 2100, lunar calendar created by above algorithm,
For the time span from 1949 to 2100, lunar calendar created by above algorithm
has only two discrepancies compare to the HKO's version: one is a solar term on
1979-01-20, the other is a new moon on 2057-09-29. It caused by few seconds of
error happens around midnight(UTC +8).
1979-01-20, the other is a new moon on 2057-09-29. It is caused by few seconds
of error happens around midnight(UTC +8).
The official timezone before 1949 is slightly different than the current UTC +8
therefor the computed lunar calendar may not represent history accurately.
@@ -38,7 +37,7 @@ This package is released under the terms and conditions of the BSD License, a
copy of which is include in the file COPYRIGHT.
**Hong Kong Observatory** has been very kind to provide and grant the permission
of using their convertion table, which is only for Non-Commercial use.
of using their conversion table, which is only for Non-Commercial use.
### Requirement:
@@ -47,8 +46,7 @@ of using their convertion table, which is only for Non-Commercial use.
* [Numpy][] and [Numexpr][]: Only needed when generate calendar by astronomical
algorithm. The full version of LEA-406 and VSOP87 is rather slow when compute
in pure python. Combine numpy and numexpr gives a perceived speed comparable
to original Fortran code.
in pure python.
### How to run
@@ -116,3 +114,5 @@ calendar, thunderbird + lightning插件, iphone/ipad, 安卓都支持。
[aa_trunc]: http://infinet.github.io/images/moon-sun-trunc_lea406_vsop87_compare_JPL.png
[Numpy]: http://www.numpy.org
[Numexpr]: https://github.com/pydata/numexpr
[LEA-406]: http://www.aanda.org/articles/aa/full/2007/33/aa7568-07/aa7568-07.html
[VSOP87]: ftp://ftp.imcce.fr/pub/ephem/planets/vsop87