Re: Calendar calculations

In sci.astro message <7de9fe67-8197-4dcb-bf56-bc6de7d99eb1@xxxxxxxxxxxxx
oglegroups.com>, Thu, 27 Mar 2008 15:57:22, HAL 9000
<rubyhacker@xxxxxxxxx> posted:
I want to do some calendar (and astronomical) calculations going back
roughly 2008 years.

Read The Calendar FAQ. Read my Web site.

So... how does our calendar define early dates? Do the leap years go
backwards? Do the Julian and Gregorian calendars agree on January 1,
Year 1?

No. They agree from 0200-03-01 to 0300-02-28.

Specifically, if I want to calculate the number of days since 1/1/1,
how
would I do it?

Is that to be 0001-01-01 Julian, 0001-01-01 Gregorian, or do you want to
take account of the Romans correcting their earlier inability to count
up to 4 correctly?

Just count 365 days per ordinary year and 366 per Leap year.

In Gregorian, 0001-01-01 was CMJD -678575 and today is CMJD 54553. You
could discover that with a COPY of <URL:http://www.merlyn.demon.co.uk/j
s-clndr.htm> (note V button).

And to throw some more astronomy into the mix, how can I find the
nearest
Martian (northern) vernal equinox to 1/1/1?

For a start, Google martian vernal equinox date .

--
(c) John Stockton, nr London, UK. ?@merlyn.demon.co.uk Turnpike v6.05.
Web <URL:http://www.merlyn.demon.co.uk/> - w. FAQish topics, links, acronyms
PAS EXE etc : <URL:http://www.merlyn.demon.co.uk/programs/> - see 00index.htm
Dates - miscdate.htm moredate.htm js-dates.htm pas-time.htm critdate.htm etc.
.