Hebrew calendar (astronomically called a lunar conjunction and, in Hebrew, a molad) is the moment at which the sun and moon are aligned horizontally with respect to a north-south line (technically, they have the same ecliptical longitude). The period between two new moons is a synodic month. The actual length of a synodic month varies from about 29 days 6 hours and 30 minutes (29.27 days) to about 29 days and 20 hours (29.83 days), a variation range of about 13 hours and 30 minutes. Accordingly, for convenience, a long-term average length, identical to the mean synodic month of ancient times (also
Military designation of days and hours Military designation of days and hours The military designation of days and hours within the North Atlantic Treaty Organisation (NATO), is specified in AAP-6 (STANAG 3680), "NATO Glossary of Terms and Definitions", and marked "(NATO)" in what follows. Those entries marked "(US)" are specific to the U.S., and defined only in Joint Publication JP 1-02, "Department of Defense Dictionary of Military and Associated Terms". References to days (or hours) preceding or following a designated day (or hour) use a plus or minus sign and an Arabic numeral following the letter. For example, "D−3" is 3 days prior to D-day, "C+7"