Determination of azimuth
To determine the declination of an direction one
needs to measure the azimuth and the apparent
Several way can be followed to determined the azimuth of a particular
building. There are generally three different ways to determine the azimuth:
The methods and tools used with these ways are discussed in more detailed
on this web page. If one is in open air most
of the mentioned tools are easily used. Don't
forget to measure the (apparent) altitude as accurate
from one point (A: like with a compass, photometry or reference object)
using two points from behind the desk (A and B: like with an map or ground
using two points (A and B: like with a GPS)
But as soon as one has to determine e.g. the average direction of a
passage or the sunniness of a building, one
has problems because a GPS and a compass don't work inside a building and
an ordinary map will not provide any input for this kind of activity.
The ways that could be used in this instance are:
Use a good ground plan of the building (from literature or made yourself).
Remember that an accurate direction must be provided by this groundplan
(like true north). Information from groundplan can be inputten in the sunniness/mooniness
page to determine the azimuth.
Make an extension of the to be measured azimuth to the outside of the building
(using a long string or a laser pen). In that way one is able to use the
compass to get the azimuthc.
If one wants to determine azimuthl
with a GPS, the end string or laser light (point B) must be at least some
800 m away from point A to get an accurate measurement (+/- 15').
Try to find in the distance a reference object (point B), that is in line
with the azimuth to be determined. One can determine the location of this
object (point B) by travelling to it and then use the GPS to gets azimuthl
or one can try to find the object on a map to get azimuthm.
Remember that point B must be at least 800 m for GPS and at least some
1.6 km for map.
Two persons are needed: One is in the building (point A) and looking
outside in the correct azimuth, the other person walks with a GPS some
distance away (more than 800 m) in such a way that it is line of the azimuth.
Now point B can be determined (as far as possible from point A) and thus
The shadow of a celestial body can also be used to determine this (certainly
when determining the sunniness/mooniness).
The azimuths of the sun/moon can be determined by ephemeris
programs. Remember that these programs determine the middle of the
celestial object and normally the shadow is determined by the left or right
rim of the object (for moon and sun this is around 16' difference).
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Last major content related changes: July 22, 2000