WP 34S conversion error

[Dieter]

(01-05-2015 10:13 PM)Didier Lachieze Wrote:  I'm not an astronomer and this may not fully answer your question but here is a hint about usage of Julian dates in astronomy:

Caveat!
There are two different things that should not get confused:

On the one hand there is the Julian calendar. Unlike the Gregorian calendar that is used today in most parts of the world, every 4th year is a leap year. According to the Julian calendar, Christmas day is today, on 7 January. In the Julian calendar, a year on average has 365,25 days.

On the other hand there are Julian day numbers. Unlike the usual notation with day, month and year, a certain point in time here is defined by a single number, which allows easy calculations by simple addition/subtraction. These Julian day numbers usually are based on the Gregorian calendar which on average has 365,2425 days per year.

Walter wondered why the light year was defined on a year being 365,25 days (i.e. like it was in the now mostly defunct Julian calendar) and not 365,2425 days (like in the Gregorian calendar) or others, e.g. 365,2422 days (= 1 tropical year).

Dieter