celestial navigation - software and formulas to calculate the estimated altitude and azimuth of a fixed star

Celestial Navigation - formulas and software

Nautical Astronomy - Planetariun in Valencia - Hemisferic


....after having collected all the data : estimated latitude and longitude, declination / polar angle of the observed celestial bodies (stars, sun, moon and planets ) and sextant reading (altitude) ....


You can download and use this excel file ( it's free ! )


a view of the opened excel file :


software of celestial navigation - nautical astronomy in excel


How to use the celestial navigation formulas in this file of nautical astronomy

You have to insert :

  • latitude and longitude (degrees- minutes-seconds) "n" for north latitude, "s" for south latitude, "w" for west longitude, "e" for east longitude
  • star declination : (degrees- minutes-seconds) "n" for north declination, "s" for south declination
  • polar angle   : (degrees- minutes-seconds) , "w" or  "e" according to the polar angle
  • true altitude . :  altitude observed with sextant (degrees- minutes-seconds) corrected (instrument  errors, refraction, and special corrections for sun and moon  and so on)


You obtain :

  • estimated (calculated) altitude
  • azimuth
  • altitude difference




celestial navigation - nautical astronomy formulas
formula estimated altitude sine altitude =  (sine latitude * sine declination) + (cos latitude * cos decl * cos polar angle) 
 formula azimuth  cotg azimuth =  ( cotg ( 90-decllination) * cos latitude * cosec polar angle ) - (sine latitude * cotg polar angle )




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