Sentinel Documentation

Sentinel Documentation

Welcome to the Sentinel documentation. Sentinel is a real-time Earth and space situational awareness display. It is designed to be simple to run, reliable in continuous operation, and clear in presentation.

Getting Started

To begin using Sentinel:

  1. Complete your purchase and download the Sentinel file from your order confirmation email.
  2. Open the file (sentinel-v1.1.0.html or similar) in a supported browser on your computer.
  3. Enter your QTH latitude and longitude when prompted, or via the settings panel.
  4. Press F11 (or your browser's full-screen key) to go full-screen.

You are operational in under 60 seconds.

Installation

Sentinel is a browser-based application with no installers, accounts, or external dependencies. It is licensed for use on a single computer by a single user. See the License Agreement (EULA) for full details.

To run Sentinel:

  • Open the Sentinel HTML file in Chrome, Edge, Firefox, or Safari on your computer.
  • Press F11 (or your browser's equivalent) to enter full-screen mode.
  • No unzipping, no setup wizard, no account creation required.

System Requirements

  • Browser: Chrome, Edge, Firefox, or Safari (latest versions). Any modern Chromium-based browser works.
  • OS: Windows 10+, macOS 11+, Linux (any modern distribution)
  • Display: 1080p or 4K single display recommended for best clarity. Designed for full-screen continuous use.
  • CPU: Any modern processor
  • RAM: 4 GB or more
  • Internet: Optional. Required for live data refresh (earthquakes, weather, alerts, TLE updates). Core display functions work offline.

Feature Overview

Global Map & Day/Night Overlay

  • Real-time day/night terminator (grayline) — computed locally, always current
  • Full-screen world map optimized for continuous display
  • Natural Earth base map

World Clocks

  • A row of global city clocks using IANA time zones
  • UTC reference always visible
  • Quick time-zone awareness for operators tracking events worldwide

Live Earthquake Data

  • USGS 24-hour GeoJSON feed
  • Magnitude-scaled markers on the map with hover tooltips
  • Statistics: strongest event, most recent event, total count, most active region
  • Feed freshness indicator showing last update time

Volcano Overlay (Toggleable)

  • Volcano locations from the USGS catalog
  • Curated list of "volcanoes of interest" for quick reference
  • Toggle on/off; your preference is remembered between sessions

Tectonic Plate Boundaries (Toggleable)

  • Global PB2002 plate boundary overlay
  • Lightweight styling for geophysical context without visual clutter
  • Toggle on/off; state is remembered between sessions

ISS & CSS (Tiangong) Tracking

  • Real-time position, orbital trail, altitude, and speed for both stations
  • Footprint visualization showing current coverage area
  • Seeded from embedded TLEs at startup, then upgraded to live CelesTrak data when internet is available
  • AOS/LOS timing relative to your QTH

Two Selectable Amateur Satellites (SAT 1 / SAT 2)

  • Selectable from a curated list of ham-friendly satellites
  • Orbit paths and footprint rings
  • In-view status based on your QTH location
  • AOS/LOS timing for lightweight pass planning
  • TLE freshness indicator

QTH (Your Location)

  • Enter your latitude/longitude to place a precise station marker on the map
  • All satellite footprint and in-view checks are computed relative to your QTH
  • Local weather and alerts displayed at your QTH via tooltips
  • QTH settings persist between sessions

Local Weather & Alerts

  • QTH-based weather snapshots and basic forecast from MET Norway
  • NWS active alerts for your location (U.S. users)
  • Displayed in the QTH marker tooltip
  • Refreshed automatically on a regular schedule

Feed Health & Status

  • Unified status bar showing the state of all major data feeds
  • Each feed labeled OK, STALE, or UNAVAILABLE with last-update age
  • Covers: earthquakes, volcano data, weather, alerts, and TLEs
  • Lets you know how current your information is at a glance

Help & Keyboard Shortcuts

  • H or F1 — Open the in-app Help overlay
  • I — Open the Info / Quick Start panel (includes links to License & Credits)
  • V — Toggle volcano overlay
  • P — Toggle plate boundaries
  • Additional shortcuts listed in the Help overlay

Offline Behavior

Sentinel continues to function with reduced capability if internet connectivity is lost.

Continues working (using last-good or embedded data):

  • ISS, CSS, and amateur satellite propagation (using last-known TLEs)
  • QTH marker, world clocks, day/night grayline, and map rendering
  • Last-good earthquake, volcano, and weather data (while cached data remains valid)

Pauses until connectivity returns:

  • New earthquake events from USGS
  • Updated TLEs from CelesTrak
  • Weather forecasts and alerts
  • Volcano catalog refresh (if remote refresh is enabled)

The feed-status bar always shows which sources are currently active.

Data Sources

Sentinel combines local computation with trusted public data feeds.

  • USGS — Earthquake feeds (FDSN Event Web Service, GeoJSON 24-hour window) and volcano catalog
  • PB2002 — Tectonic plate boundaries (Peter Bird, 2003), packaged via the community tectonicplates GeoJSON repository
  • Natural Earth — Base map components (public domain)
  • CelesTrak — Orbital elements (TLE/OMM) for ISS, CSS, and amateur satellites
  • MET Norway (met.no) — Locationforecast 2.0 compact forecast endpoint for QTH weather
  • NWS (api.weather.gov) — Active weather alerts for U.S. locations
  • satellite.js — SGP4 orbital propagation library (MIT license)
  • Day/night grayline — Computed on-device from astronomical formulas (no external API)
  • World clocks — Rendered locally using IANA time zones via the browser's Intl APIs

Full attribution and licensing details: Sentinel Third-Party Notices & Data Credits

Version

Current version: v1.1.0

See Release Notes for the full change history.

Support

If you need help, contact us via the Contact page. Include your order number, browser, OS, and a description of what you're seeing.