Almanak Nautika Overview and Acquisition
📌 The Nautical Almanac (Almanak Nautika) is an essential navigational aid used to decipher the positions of celestial bodies for determining a vessel's location using astronomical navigation.
📚 The official almanac is published annually and must be ordered or purchased from the Indonesian Navy (TNI Angkatan Laut).
💻 For those needing a free alternative, the almanac can be downloaded in PDF format from `nauticalalmanac.com`.

Historical References for the Almanac
⭐ The Indonesian Nautical Almanac references data from three primary historical sources: Great Britain's *The Nautical Almanac* (since the 18th century), the *United States Nautical Almanac* from the U.S. Naval Observatory (since the 19th century), and the Admiralty Nautical Almanac.
🧐 These historical references are explicitly indicated within the current Indonesian Navy edition (e.g., by markings from the HMS Nautical Almanac Office and U.S. Naval Observatory).

Time Systems: GMT, UTC, and Time Zones
⏱️ Calculations in the almanac for the Sun, Moon, planets, and 57 stars rely on Greenwich Mean Time (GMT), which is the reference time based on the Earth's position relative to Greenwich, London (0° longitude).
🌐 Indonesia operates across three GMT zones: GMT +7, GMT +8, and GMT +9.
⌚ UTC (Universal Time Coordinated) is presented as being virtually identical to GMT, though UTC is more accurate to the second; GMT zones indicate whether a location is ahead (+) or behind (-) Greenwich time.

Contents and Structure of the Nautical Almanac
📖 The almanac is structured around daily data presented across facing left and right pages covering a three-day period.
🌟 The left page primarily tabulates data for navigation stars and planets, crucial for calculating times for dawn, dusk, and twilight.
☀️ The right page provides daily data for the Sun and Moon, including their sunrise/sunset and moonrise/moonset times.
⚙️ Interpolation data (increments and corrections) is necessary to calculate the precise Greenwich Hour Angle (GHA) and Declination (Dec) for the exact observation time (in full GMT hours).

Key Components Detailed in the Almanac Pages
🌠 Key sections include the date based on GMT, GMT time (in 24-hour format), Mean Right Ascension (RMpas) at 0° Greenwich, and various corrections (V correction and Dec correction) for planets.
⭐ Star Data (Item 5): Lists GHA and Declination for 173 stars, including 57 selected stars, tabulated monthly.
🌙 Lunar Data (Items 13-20): Includes V correction for the Moon, Semi-Diameter (SD) of the Moon, Declination (Dec), and Lunar Age (Egg), representing the days since the last new moon.

Key Points & Insights
➡️ Always rely on the Nautical Almanac as a backup reference in case of electronic navigation system failures, as technology is prone to error.
➡️ Understanding GMT calculations (addition for + zones, subtraction for - zones) is fundamental to correctly applying the almanac data to a vessel's local time and position.
➡️ Be aware that the date in the almanac corresponds to GMT and might differ by one day from the local date depending on your longitude.
📢 Educational Opportunity: The Indonesian Ministry of Maritime Affairs and Fisheries is currently accepting applications for various maritime education levels until July 27th.

📸 Video summarized with SummaryTube.com on Dec 05, 2025, 06:59 UTC