Navigation Almanac

Now in sixteen languages, with the navigation terminology in each taken from that country's own nautical almanac. Sky View now predicts the GNSS satellites overhead.

Navigation Almanac is a complete celestial-navigation toolkit for iPhone and iPad. It reduces a sight, tabulates the almanac data you would otherwise look up on paper, and works entirely offline — no signal, no subscription, no account.

SIGHT REDUCTION Enter your position and the date and time in UTC or local time, then pick a body. You get azimuth and computed altitude, GHA, LHA, SHA and declination, semi-diameter and horizontal parallax, along with the magnetic variation from the WMM-2025 model and the current value of ΔT.

ALMANAC The Sun, Moon, Venus, Mars, Jupiter and Saturn together with the 57 navigational stars, each with azimuth, altitude, hour angles and declination for the moment you have chosen.

RISE, SET AND TWILIGHT Rise, meridian transit and set for any body, with civil and nautical twilight at the Sun's standard altitudes (−0°50′ / −6° / −12°), shown in UTC or local time.

SKY VIEW The sky drawn as a chart of azimuth against altitude, or as a full-sky dome with the zenith at the centre. Background stars, constellation lines, and a predicted GNSS satellite layer computed from a bundled orbital catalogue.

GPS Live position, course and speed over ground, altitude and horizontal accuracy, the magnetic variation at your position, and the ephemeris of the selected body. One tap fills the observer position for a reduction.

COMPASS ERROR Solve gyro and magnetic compass error from an observed bearing, with variation and deviation kept separate, the way the correction is actually applied on the bridge.

FIX CALCULATOR Cross two lines of position from your reductions, advance the first line for the vessel's run between sights, and read off the observed position.

WORKS OFFLINE The ephemerides are computed on the device from the VSOP87 and ELP2000 series with IAU 1980 nutation — they are not downloaded. Everything above works with the phone in airplane mode, weeks from shore.

SIXTEEN LANGUAGES English, Russian, Ukrainian, French, Spanish, Italian, Portuguese, German, Dutch, Polish, Swedish, Danish, Greek, Turkish, Latvian and Simplified Chinese. The navigation terminology in each was taken from that country's own nautical almanac and navigation textbooks rather than translated word for word.

Navigation Almanac is a computational aid. Carry the official almanac and tables required for your voyage.