Wndsn Star Calculator
High-precision star calculator. Companion to Wndsn Quadrant Telemeters: Low tech, high utility graphical distance computers from the Wndsn applied science lab.
To use, enter the latitude of your observation point, choose the name of the observed star or input its declination, and measure the altitude of the star with your quadrant. The resulting set of data can be used for cardinal direction and time determination.
Calculating the altitude of a star's culmination from the southern horizon.
Input
Results
The formulas used are proof-of-concept formulas based on ancient formulas of spherical trigonometry and ignore specifics like nutation, precession, etc. The calculated results are FOR EDUCATIONAL PURPOSES ONLY; some are exact, some are approximate, and some are simplified. Actual star data may vary significantly.
Input
- Latitude of observation point:
52.5° - Star declination:
-8.18° - Selected navigational star:
RIGEL (β Orionis) - Observed star altitude:
10°
Output
- Rise azimuth from North (true horizon):
103.52° - Set azimuth from North (true horizon):
256.48° - Altitude of the upper culmination:
29.32° - Altitude of the lower culmination:
-45.68° - Star azimuth from altitude:
117.85° - Star hour angle from altitude from South:
61.61° - Star hour angle from altitude (hours to or since culmination):
04:06
Negative values typically mean that the star is below the horizon, and hence not visible, no values typically mean that the star is circumpolar, that is it is always visible at the location and does not set nor rise.
The display precision set is .2. To change that, edit the variable &digits=x in the URL where 0 <= x <= 9.
Explanation
Observing and measuring the 59 navigation stars, which are bright enough to be recognized in the sky with moderate light pollution, we can determine cardinal direction, location, and even time.
For a comprehensive tutorial, see The Quadrant Telemeter: A Star Compass.
[Load sample values (JSON) (XML) (CSV).]