Observance Days can serve as important markers in our lives when we can rededicate ourselves to our spiritual practice. These dates are usually based on the lunar calendar but may vary from it as they are calculated in a traditional manner in each Buddhist country. The Full Moon Day is observed by the majority of practicing Buddhists and many also observe the New Moon and Quarter Moon days.
The phases and times below are for the GMT/UTC time zone in the Northern Hemisphere.
The Five Spiritual Faculties by Bhikkhu Bodhi