I am using the ICU4J components, especially the HebrewCalendar, for a personal
project.
The fact is that in the Jewish tradition, the day D begin the day D - 1 when
the
sun is down (sunset) and finish at the day D at sunset.
A Jewish day is composed with 2 parts, called ONA (or ONOTH for the plural) :
- The night ONA start the day before at sunset and finish on the morning at
sunrise,
- The day ONA start at sunrise and finish at sunset.
In my project, I have to distinguish from the two ONOTH and I need to compute
the sunset time and the sunrise time.
In order to do that, I tried to use the CalendarAstronomer.class which is part
of the ICU4J components.
Here is the problem:
The algorithm to compute the astronomic sunrise and sunset of the sun use the
CENTER of the sun in order to say that the sun rise or set.
BUT, in the Jewish tradition, we say that the sun rise when the first sunbeam
is
visible (so before the astronomic sunrise) and we say that the sun set when the
last sunbeam disappears (so after the astronomic sunset).
I am not an astronomic algorithm expert and I look at the CalendarAstronomer
source code but I didn't find any thing that I understand in order to modify
the
source code or to put or modify some parameter in order to compute the sunset
and sunrise accordingly to our tradition.
Is it possible to you or to your team to have a look at this problem, trying to
find a solution for me ?
I understand that modifying the Calendar and its subclasses can be a very
difficult task in order to have the day transition at sunset. At least, we can
manage the transition outside of the Calendar as soon as we have a mean to
compute the sunset and sunrise time accordingly to our tradition.
I am sure that a lot of Jewish people that will use this component will also
appreciate this functionality.
Thanks in advance for any help and from anybody.
