For monastics, these are often days of more intensive
reflection and meditation. In many monasteries
physical labor (construction projects, repairs, etc.)
is curtailed. On New Moon and Full Moon days the
fortnightly confession and recitation of the
Patimokkha (monastic rules of conduct) takes place.
Lay people observe the eight precepts on Uposatha
days, as a way of re-energizing commitment to Dhamma
practice. If possible, lay people use these days as a
time to visit the local monastery, in order to make
special offerings to the Sangha, to listen to Dhamma,
and to practice meditation with Dhamma companions late
into the night. For laity not closely affiliated
with a local monastery, it can simply be an
opportunity to increase one's efforts in meditation
while drawing on the invisible support of millions of
other practicing Buddhists around the world.
Uposatha observance days (1999)
Last Quarter New moon 1st Quarter
Full Moon
~~~~~~~~~~~~ ~~~~~~~~ ~~~~~~~~~~~
~~~~~~~~~
Jan 10* Jan 17*
Jan 25* Jan 31
Feb 8 Feb
15* Feb 23*
Mar 1
(Magha Puja)
Mar 9 Mar
16 Mar 24
Mar 31
Apr 8 Apr
15* Apr 23*
Apr 30*
May 8* May 15*
May 23* May 29
(Visakha Puja)
Jun 6 Jun
13* Jun 21*
Jun 28*
Jul 6* Jul 13*
Jul 21* Jul 27
(Asalha Puja)
Aug 4 Aug
11 Aug 19
Aug 26
Sep 3 Sep
10* Sep 18*
Sep 25*
Oct 2 Oct
9 Oct 17
Oct 24
(Pavarana Day)
Nov 1 Nov
8* Nov 16*
Nov 23*
(Anapanasati
Day)
Dec 1* Dec 7
Dec 15 Dec 22
Dec 30
Some of the full-moon days have special significance
in the Buddhist calendar.
Source:
http://world.std.com/~metta/dhamma/uposatha.html