Meridian Nav

Meridian is a celestial navigation toolkit built at sea by a working deck
officer — fully offline, because mid-ocean is exactly where you need it.

SIGHT REDUCTION
Compute Hc, Zn and intercept for the Sun, Moon, four planets and 63
navigational stars. Enter your DR position, date/time and sextant altitude
— get your line of position.

COMPASS ERROR
Check gyro error by azimuth of any celestial body — the daily routine,
without the almanac and tables. Magnetic variation (WMM2025) is built in
for magnetic compass work.

STAR FINDER
A polar sky-dome view shows exactly which bodies are observable right now
from your position — plan your twilight sights before stepping out on
the bridge wing. Includes an azimuth-scatter view for picking the best
LOP geometry.

SUN / MOON
Rise, set, meridian passage and twilight times for any position and date.

MARINE CHART — FULLY OFFLINE
A custom offline vector chart with world time-zone (ZD) boundaries, DST
awareness, ports and waypoint routes. Import route files (.rtz / .rou)
straight from your ECDIS.

CLOCK PLAN
Generate the entire voyage's retard/advance schedule from your route —
including DST transitions and solar-zone departures. Reorder or edit the
changes, then export a clean calendar-style PDF or Excel notice, ready to
post on board.

UNIT CONVERTER
The conversions a navigator actually uses, in two taps.

ACCURACY & VALIDATION
Every body — Sun, Moon, planets and 63 navigational stars — is
cross-checked against JPL ephemeris data (the same source behind the
official Nautical Almanac) to arc-minute agreement. Star positions are
computed for the current date from the ESA Hipparcos catalogue. Sun
azimuth verified at sea against a ship's bridge calculator, and against
NOAA's solar calculator (0.000° difference).

MADE FOR
Deck officers who want a fast backup and sanity check, cadets and
officers studying celestial navigation, and anyone who believes a
navigator should still be able to find a ship without a satellite.

No account. No ads. No subscription. No internet required. One-time
purchase.

IMPORTANT
Meridian is a reference and training aid for celestial navigation. It is
not a certified navigation system and does not replace official nautical
publications, charts, or type-approved equipment.