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1. The percent of the Moon's surface illumi-
nated is a more refined, quantitative description of the
Moon's appearance than is the phase. Considering the
Moon as a circular disk, at New Moon the percent
illuminated is 0; at First and Last Quarters it is 50%;
and at Full Moon it is 100%. During the crescent
phases the percent illuminated is between 0 and 50%
and during gibbous phases it is between 50% and
2. For practical purposes, phases of the Moon
and the percent of the Moon illuminated are
independent of the location on the Earth from where
the Moon is observed. That is, all the phases occur at
the same time regardless of the observer's position.
3. For more detailed information, refer to the
United States Naval Observatory site referenced
d. Access to Astronomical Data for Determina-
tion of Moon Rise, Moon Set, and Percentage of
Lunar Disk Illuminated
1. Astronomical data for the determination of
Moon rise and set and Moon phase may be obtained
from the United States Naval Observatory using an
interactive query available at:
2. Click on "Data Services," and then on
"Complete Sun and Moon Data for One Day."
3. You can obtain the times of sunrise, sunset,
moonrise, moonset, transits of the Sun and Moon, and
the beginning and end of civil twilight, along with
information on the Moon's phase by specifying the
date and location in one of the two forms on this web
page and clicking on the "Get data" button at the end
of the form. Form "A" is used for cities or towns in the
U.S. or its territories. Form "B" for all other locations.
An example of the data available from this site is
shown in TBL 10-2-2.
4. Additionally, a yearly table may be
constructed for a particular location by using the
"Table of Sunrise/Sunset, Moonrise/Moonset, or
Twilight Times for an Entire Year" selection.
Sample of Astronomical Data Available
from the Naval Observatory
The following information is provided for
New Orleans, Orleans Parish, Louisiana
(longitude W90.1, latitude N30.0)
Tuesday Central Daylight Time
29 May 2007
Begin civil twilight 5:34 a.m.
Sunrise 6:01 a.m.
Sun transit 12:58 p.m.
Sunset 7:55 p.m.
End civil twilight 8:22 p.m.
Moonrise 5:10 p.m. on preceding day
Moonset 4:07 a.m.
Moonrise 6:06 p.m.
Moon transit 11:26 p.m.
Moonset 4:41 a.m. on following day
Phase of the Moon on 29 May: waxing gibbous with
95% of the Moon's visible disk illuminated.
Full Moon on 31 May 2007 at 8:04 p.m. Central
10-2-3. Landing Zone Safety
a. This information is provided for use by
helicopter emergency medical services (HEMS)
pilots, program managers, medical personnel, law
enforcement, fire, and rescue personnel to further
their understanding of the safety issues concerning
Landing Zones (LZs). It is recommended that HEMS
operators establish working relationships with the
ground responder organizations they may come in
contact with in their flight operations and share this
information in order to establish a common frame of
reference for LZ selection, operations, and safety.
10-2-10 Special Operations