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I found a link to FM 6-50 chapter 5 which contains the information
about these techniques.

http://www.globalsecurity.org/military/library/policy/army/fm/6-50/Ch5.htm#s2p4


gl

On Aug 17, 2:41 am, glap...@PACBELL.NET wrote:
> Here is another use of celestial techniques that you probably didn't
> know about.
>
> When firing long range cannons at targets many miles away that are
> not
> in sight you must calculate in exactly what direction you must point
> the
> guns to hit the target and at what elevation you have to launch the
> projectile for it to travel the exact distance to the target. You
> take
> into account many factors including powder temperature (warmer powder
> burns faster creating more pressure, raising muzzle velocity), bore
> erosion (each shot causes some of the bore to wear away allowing more
> powder gasses to escape around the projectile resulting in lower
> muzzle
> velocity),  the exact weight of the projectile, winds and air density
> at
> different altitude levels (some projectiles go up to 30,000 feet in
> altitude), the difference between the height of the guns and of the
> target above sea level, the fact that the trajectory is not rigid in
> space, that gyroscopic and aerodynamic forces working on the
> projectile
> cause it to drift to the right (with right hand rifling), and that
> the
> earth will turn an appreciable amount while the projectile is in
> flight
> which can be up to ninety seconds. It goes without saying that you
> must
> accurately know the location of the guns and the target for the
> computation.
>
> It is also necessary to determine a very accurate direction reference
> for the sighting equipment on the guns. The person in charge of
> positioning the guns uses an "aiming circle" which is an instrument
> much
> like a transit to do this. But first he must establish direction for
> the
> aiming circle and there are several ways to do this. The least
> accurate
> way is to use the built in compass but this is only accurate to about
> ten mils, about one half of a degree. A better way is for a survey
> team
> to come to the position which establishes the coordinates of the
> position and also a direction by the positioning of two stakes on a
> known azimuth as established by the survey party. This is good to one
> mil.
>
> There are also two methods which utilize celestial. One is called
> "simultaneous observation" in which personnel at battalion
> headquarters,
> at a prearranged time,  track the sun with an aiming circle while the
> three outlying firing batteries at three different locations (10 to
> 15
> kilometers away) do the same while listening to battalion on the
> radio
> saying "tracking...tracking...tracking...tip" at which point you stop
> tracking the sun and deflect the line of sight down to ground level
> and
> direct an assistant to emplace a stake on that azimuth. The
> headquarters
> then informs you what that azimuth is that they have determined, most
> commonly by survey, or by celestial computation.
>
> Another method of establishing direction involving celestial involves
> using the aiming circle to observe polaris. You set up the aiming
> circle
> and set the recording scale to zero. You then sight on polaris using
> the
> non recording motion to move the line of sight right or left which
> allows the scale to remain set on zero. After you do this you use the
> recording motion to measure the azimuth of kochab in relationship to
> the
> zero point established with polaris. You then looked at a graph
> contained in Field Manual FM 6-50 which gave you the true azimuth of
> polaris based on the azimuth of kochab (actually the difference in
> the
> azimuth of polaris and kochab.) This allowed for the daily movement
> of
> polaris around the true pole. You then returned the aiming circle
> telescope to the zero point, deflected it downward, and had an
> assistant
> emplace a stake on that azimuth. The graph in FM 6-50 was calculated
> for
> the latitude of Germany (go figure) and for the 1970s. I don't
> remember
> the graph being updated to allow for the change in the coordinates of
> polaris.


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