I believe that astro can be best understood by dealing with sight taking, the method and the calculations separately.
- Measure altitude of celestial object above the horizon.
- Measure altitude of celestial object using an artificial horizon.
- Measure altitude of celestial object using a bubble sextant.
- Measure altitude of celestial object using an esoteric device such as a Bris sextant.
There are many ways in which the observed data can be used:
- Noon Sight for Latitude
- Ex-Meridian sight for Latitude
- Equal altitudes for Longitude
- Longitude by Chronometer (a form of Time Sight)
- Time sights with position determined by Sumner Lines.
- Double Chronometer for Latitude and Longitude - time sights.
- Marc St Hilaire Intercept method - known as the New Navigation.
- Double Altitudes. Various methods, includung mixing Sumner lines and the intercept method (aka New Navigation.)
- Intersecting circles of equal altitude.
- Lunar for time and longitude
Reduce The Sight
There is a plethora of ways in which a sight can be reduced:
- Longhand with mathematical tables.
- Short methods using tables.
- Inspection tables.
- Slide rules, including the Bygrave and the German MH1.
- Electronic - calculator, phone app, spreadsheet or online calculator.
Last Updated: Saturday 13th August 2016