# Compass Observation App > Compass error, Gyro error, sight reduction & AR star finder for mariners. Canonical page: [https://chrome-stats.com/d/com.burak.compassobservationapp](https://chrome-stats.com/d/com.burak.compassobservationapp) ## Overview - **ID:** `com.burak.compassobservationapp` - **Platform:** Android - **Type:** Android app - **Status:** Available - **Publisher:** Mariner's Hand App - **Category:** TOOLS - **Downloads:** 5,254 - **Version:** 2.0.0 - **Last updated:** 2026-09-03 - **First published:** 2025-06-30 - **Publisher country:** TR - **Size:** 30 MB - **Data as of:** 2026-09-06 - **Store listing:** [Google Play Store](https://play.google.com/store/apps/details?id=com.burak.compassobservationapp) - **Website:** [https://www.marinershandapp.com/](https://www.marinershandapp.com/) - **Privacy policy:** [https://www.marinershandapp.com/compassobservation/privacypolicy/](https://www.marinershandapp.com/compassobservation/privacypolicy/) ## Description Compass Observation App is a celestial-navigation and compass-checking toolkit for deck officers, watchkeepers, yachtsmen and students of navigation. Enter your position and UTC time and it computes the true bearings, altitudes, and rise/set times of the Sun, Moon, planets and navigational stars — so you can check your gyro and magnetic compass, reduce a sextant sight, build a deviation card, and find your way around the sky.

Everything runs on the device and works fully offline — no signal needed at sea.

COMPASS ERROR
• Gyro and standard/magnetic compass error from an azimuth of any celestial body, in real observation-book order.
• Automatic true bearing, compass error, variation and deviation.
• Editable variation — use the chart value or the built-in World Magnetic Model.
• SOLAS gyro-error and 5° deviation cautions.
• Save readings to the logbook or a deviation card.

SIGHT REDUCTION (Intercept Method)
• Enter sextant altitude (Hs), index error, height of eye and limb.
• Get observed altitude (Ho), calculated altitude (Hc), azimuth (Zn) and the intercept — toward or away — ready to plot.

DEVIATION CARD (Swing Ship)
• Record deviation at any heading and build a proper deviation card.
• Smooth deviation curve with A–E coefficients; read the deviation at every heading.
• Delete or replace readings; export a clean PDF report.

STAR DOME & AR SKY FINDER
• Live sky view that rotates with your phone's compass, with pinch-zoom.
• Full star field, accurate Moon phase, twilight-aware horizon, and a constellation lines/names toggle.
• AR mode overlays stars, planets and the real (moving) Milky Way on your camera, with on-device alignment calibration and a "GoTo" pointer for any body.

LOGBOOK
• Persistent history of compass checks and sights, with headings and position.
• Filter, view details, undo deletes, and export to CSV.

BODIES & DATA
• Sun, Moon, all seven planets, the 57 Nautical-Almanac stars and Polaris, plus a background star field and the 88 constellations.
• Rise, set, transit and civil/nautical/astronomical twilight times.
• Magnetic variation from the World Magnetic Model.

BUILT FOR THE BRIDGE
• Manual position/UTC entry or GPS.
• Light, dark and a red night-vision theme to protect dark adaptation on watch — carried through to the sky views.

Positions are computed with established astronomical theory (Meeus / VSOP87 / ELP-2000), agreeing with reference ephemerides to a few arcseconds — comfortably within sextant precision.

Please note: this app is a navigation aid and practice tool. It is not a legal replacement for the official Nautical Almanac or approved navigation equipment. Always cross-check with official publications and keep a proper lookout. ## Rankings - #702,173 — Overall - #15 — variation ## Permissions and access ### Permissions - `android.permission.ACCESS_COARSE_LOCATION` - `android.permission.ACCESS_FINE_LOCATION` - `android.permission.CAMERA` - `android.permission.READ_EXTERNAL_STORAGE` - `android.permission.RECORD_AUDIO` - `com.android.vending.CHECK_LICENSE` - `com.burak.compassobservationapp.DYNAMIC_RECEIVER_NOT_EXPORTED_PERMISSION` ## Similar extensions and apps - [Compass App by SDPO Alim](https://chrome-stats.com/d/org.ofa.compassapp) — 18 users - [GyroCop](https://chrome-stats.com/d/com.dlyaverapps.gyrocop) — 57 users - [CoNav](https://chrome-stats.com/d/com.androidapp.conav) — 14,057 users - [Celestial Navigator](https://chrome-stats.com/d/com.vikrant) — 6,994 users, 3.38 / 5 - [Compass](https://chrome-stats.com/d/jacky.justin.compassapplication) — 626,068 users, 3.77 / 5 - [Compass Guide:Navigation App](https://chrome-stats.com/d/com.appsbay.compass_guide) — 465 users - [Augview Compass](https://chrome-stats.com/d/com.augview.augviewcompass) — 8 users - [Smart Compass](https://chrome-stats.com/d/com.tempo.spectrumiq.compass) — 156 users - [Compass](https://chrome-stats.com/d/app.kiwwi.compass2) — 7,917 users - [Compass](https://chrome-stats.com/d/com.ryantechlabs.compass) — 237 users - [Compass - Smart & Accurate](https://chrome-stats.com/d/com.smarttoolsdev.simplecompass) — 1,952 users - [Compass: Direction & Level](https://chrome-stats.com/d/app.simplecompass) — 1,153 users --- Source: [Chrome-Stats](https://chrome-stats.com/d/com.burak.compassobservationapp)