GPS Anti Spoof Pro vs Celestial Nav

Instantly compare observed celestial navigation altitudes with high precision, live calculated altitudes. Shoot the Sun, tap pause in the app, and get instant feedback. Standard version includes data for the Sun, Venus, and two stars. The Pro version of the app is for serious navigation use and includes data for the Sun, Moon, Venus, Mars, Jupiter, Saturn, the 57 standard navigational stars, plus Polaris. Both versions function off-network and at sea however the standard version only works for ten days off-network. The Pro version can function for weeks in the middle of the ocean without network access. This app calculates the exact sextant altitude that should be observed in celestial navigation at sea or on land assuming that the GPS position is correct. No paperwork is required, no tables of corrections. All corrections are included automatically: index error, system time error, dip of the horizon, refraction, temperature and pressure corrections to refraction, altitude above sea level, parallax, and also gravitational deflection of the vertical (a correction of up 2 nautical miles not handled by any other celestial navigation sight-clearing product) are all included automatically. If the GPS position is wrong, due to Spoofing at sea, observations will not match. With this app and occasional quick sextant sights, mariners can reliably detect GPS spoofing. No GPS Spoofing? The app also functions as a celestial navigation trainer: take a sextant sight and immediately compare against the app's display. No paperwork and instant feedback will improve celestial sextant skills in hours instead of days or weeks.  The app works off-network, even in the middle of the ocean. If a network connection is available, the app will download temperature and pressure information automatically. Or weather data can be entered manually, if desired. The ephemeris data is generated from the same JPL numerical integrations of lunar and planetary motions used by the official Nautical Almanac and Astronomical Almanac. All coordinates are accurate to one second of arc, and displayed altitudes are accurate to a tenth of a minute of arc.

We believe celestial navigation is an amazing skill and develop Celestial Nav to offer a simple, yet powerful and all encompassing app for our users. Celestial Nav is an easy to use, all-in-one tool which offers: • Celestial navigational computations for your device • Simple toolbar menu for quick access • Internally stored perpetual Almanac • Offline ready and functional without the need for other external tools • Quick and easy capture celestial observation data • High accuracy sight reductions • Star reference tables SIGHT PLANNING • Local Hour Angle (LHA) for Aries • Star tables sorted by name, magnitude, declination, and SHA • Sunrise, sunset, twilight, and location reference • Moon phase reference SIGHT REDUCTION • High accuracy sight reduction algorithm • Perpetual Almanac offering accurate data for years 1600 - 3000 • Almanac data for Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn • Detailed Almanac data for 58 navigational stars • Assumed Position (AP) for any user defined position • Line of Position (LOP) intercept data for accurate course and speed adjustments • Computational variables displayed for accuracy and validation CELESTIAL FIX • Computations by USNO algorithm in the Nautical Almanac • Save all your LOP in an easy reference table BASIC VERSION Free daytime celestial navigation tools using the sun: • Unlimited sextant sight reduction calculations • Sight reduction to a line of position using the sun • Perpetual almanac for the sun • Advanced sight corrections for index error, eye height, temperature, and pressure • Support for upper and lower limb reference • Star Table with navigational references • Detailed Sun references • Limited Moon references PRO FEATURES (IN-APP PURCHASE) Advanced Day & Night Celestial Navigation includes all BASIC features plus: • Almanac data for 65 navigational bodies for years 1600 through 3000 • Map display for saved LOPs • View intercepts with course and speed corrections • Metric and imperial unit support with automatic conversions • Support for coordinate entries in different formats (H° M’ S” or Decimals) • Save all your LOP calculations for future reference • Save user preferences and settings • Unrestricted moon references • Almanac and algorithmic models for 65 navigational bodies: • Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn • 58 navigational stars Supported stars: Acamar, Achernar, Acrux, Adhara, Aldebaran, Alioth, Alkaid, Alnair, Alnilam, Alphard, Alphecca, Alpheratz, Altair, Ankaa, Antares, Arcturus, Atria, Avior, Bellatrix, Betelgeuse, Canopus, Capella, Deneb, Denebola, Diphda, Dubhe, Elnath, Eltanin, Enif, Fomalhaut, Gacrux, Gienah, Hadar, Hamal, Kaus Australis, Kochab, Markab, Menkar, Menkent, Miaplacidus, Mirfak, Nunki, Peacock, Polaris, Pollux, Procyon, Rasalhague, Regulus, Rigel, Rigil Kent., Sabik, Schedar, Shaula, Sirius, Spica, Suhail, Vega, Zubengenubi REFERENCES Sight reductions and celestial calculations use various internationally accepted references for the most accurate results: • Jean Meeus - Astronomical Algorithms • US Naval Observatory (USNO) Almanac and Algorithms • Hipparcos New Astrometric Catalog, Published 2007 • ELP2000-85 SUBSCRIPTION TERMS Celestial Nav is free to download and the basic features free to use. A paid upgrade to the PRO version provides access to premium features and additional tools. We may offer trial subscriptions that give limited time access to all PRO features and premium content for the duration of the trial period. Trial subscriptions automatically expire and the app will revert back to the Basic version thereafter. No data is lost but access and use of premium features will no longer be available.