# Navigation, Astronavigation, Positioning and Geodesy

This Javascript-program asks the Latitude and the Longitude of two
Locations and calculates great circle distance, the initial course and the
arrival course. In the Homepage of National
Geospatial-Intelligence Agency is Nautical Calculator which
calculates only on Sphere. Look
"Nautical Calculators" , from there "Sailings".

My Javascript calculates by Vincent's iteration method on WGS84 Ellipsoid
the distance on accuracy of one millimeter. Thus it is suitable also for
geodetic calculations.

Javascipt program asks the Origin, the Initial Course and the Distance. It
calculates the Destination. Program uses by Vincenty's iteration method.
This Jacascript-program asks the latitude and the longitude of the two
locations and calculates constant Course between locations.
Javascipt program asks the Origin, the Constant Course and the Distance. It
calculates the Destination.
Javascript program asks the altides of two stars, their declinations and
right ascentions, Greenwich Mean Time (UT) and assumed location of the
measurement place. After that the program calculates the exact Latitude and
Longitude using Newton's iteration method. The accuracy is as good as the
accuracy of measurements. The best assumed location is obtained from dead
reckoning, but it also can be very inexact. It is enough to know being
somewhere on Atlantic or somewhere on Pacific Ocean...:-) The Newton
Iteration method very quickly finds exact position corresponding
measurements.
This is not so exact as two star's altitude method.

It is suitable in emergency situations when only one star is visible.

First you can recognize the star from altitude and azimuth. After that you
get exact declination and right ascention of the star from navigation or
astronomical table.

Latitude and Longitude is calculated using Newton's iteration method.
Calculate Julian Day Number, Julian Date, Greenwich Mean Sidereal Time GMST,
Hour Angle, Local Hour Angle LHA, Greenwich Hour Angle GHA. Calculate
Sidereal Hour Angle from Right Ascention.

Paluu
Juhani Kaukoranta
Last changes 14.10.2022