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Anomalistic solar calendar (was: Part2, Joining list. Calendar reforms)

by Karl Palmen :: Rate this Message:

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Dear Amos and Calendar People

365 95/366 days = 365.25956284 days, which is quite close to the anomalistic year, but not the sidereal year as stated by Amos, but the anomalistic year is the year that Amos requires. A calendar with the same years, but with one day removed once every 57 of its years, would have a mean year of 365.24201898 days.

The mean month resulting from dividing the 336-year cycle into three 122-year cycles of 1509 months is 29.5305942125 days, which is remarkably close to the Hebrew mean month. The 122-year cycle can for formed from six 19-year cycles and an Octaeteris (6*19+8=122 & 6*235+99=1509).

For the suggested 366-year cycle leap year rule, I think Amos meant (year Y is leap if ((Y mod 366) mod 27) mod 4 == 3);. This gives 14 27-year cycles with a total of 98 leap years from which 12 years of 3 leap years have been cut from the end. These leap years are not spaced as evenly as possible.

Karl

10(09(03

From: East Carolina University Calendar discussion List [mailto:CALNDR-L@...] On Behalf Of Amos Shapir
Sent: 24 May 2009 15:15
To: CALNDR-L@...
Subject: Astronomical sidereal calendar (was: Part2, Joining list. Calendar reforms)

A tropical calendar may be difficult, but this can be made simpler by defining the calendar along the sidereal year. A convenient cycle is 366 years with 95 leap (year Y is leap if (Y mod 27) mod 4 == 3); it can be started on apphelion or perihelion day, with 5 or 6 long months around the apphelion, the same way the Iranian calendar does.

To make it into a tropical calendar, just shift the starting day by 1 day every 57 years (that may change in the future), but keep month lengths the same as the overlapping sidereal months.

A lunar calendar of 122 years, 1509 months, can be superimposed on the same cycle. Longer lunar months should be concentrated around the perihelion, by keeping leap months and days closer to that point.

(Perl source is available if anyone wants the gory details)

Amos Shapir

Date: Sat, 23 May 2009 23:34:25 -0400
From: irv.bromberg@...
Subject: Re: Part2, Joining list. Calendar reforms.
To: CALNDR-L@...

...

If you look in the archives of this CALNDR LISTSERV you will see some threads about Shriramana Sharma's STAY calendar, which was proposed as an astronomical calendar that would have a rule for advancing which 6 months would have 31 days. The proposal proved problematic to actually implement in calendar arithmetic, Shriramana never got it working. I also tried and gave up. It is difficult to avoid oscillations of the 31-day months from year-to-year unless special rules are adopted to prevent such oscillations. Such rules could include using the mean perihelion instead of the actual perihelion, and probably not changing the month lengths more frequently than at century boundaries.

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