Spot the International Space Station (ISS) from your wrist. ISS Horizon tracks the space station in real time using your watch's GPS coordinates, predicts when it will fly over your location, and warns you before a visible sighting begins. 4 TACTICAL VIEWS (Cycle with UP / DOWN): 1. Sky Dome Radar & Live Countdown • Polar horizon radar (N/E/S/W compass ring with 0°, 30°, and 60° elevation rings). • Live ticking countdown (HHh MMm SSs) to the next pass over your location. • Plots the projected sky trajectory curve and live ISS target reticle when above the horizon, or an amber perimeter bearing indicator showing which direction the station currently lies when below the horizon. • Real-time Azimuth (degrees + compass cardinal), Elevation angle, Slant Range (km), and Solar Illumination status (Sunlit vs Eclipse). 2. Live 3D Earth Globe • 3D orthographic globe centered on the ISS sub-satellite point. • Displays 3D continental outlines, latitude/longitude graticule, and the 90-minute orbital ground-track wave. • Shows the station's 2,200 km horizon visibility footprint ring alongside your GPS location pin so you can see the pass footprint approach your position in real time. 3. 24-Hour Upcoming Passes Forecast • Lists the next 3 passes over your GPS coordinates within the next 24 hours. • Shows local rise time, countdown, peak elevation angle, sky path (e.g., WSW-E), pass duration, and whether the pass is naked-eye Optical Visible (sunlit ISS + dark local sky) or a Daytime Overhead pass. 4. Orbital Telemetry & Configuration • Live ISS latitude/longitude, orbital altitude (km), orbital speed (7.66 km/s), GPS lock status, and active alert filter. SIGHTING WARNINGS & ALERTS: • Background Wake Alarm (T-5 Minutes): Automatically schedules a low-power hardware wake alarm 5 minutes before your next qualifying pass so your watch alerts you even when the app is closed. • Pre-Pass Warning (T-10 Minutes): Double-pulse vibration and tone alert with compass rise direction and max elevation. • Active Sighting Alert (Above Horizon): Triple-pulse tactical vibration, high-priority alert tone, and on-screen directional banner ("ISS VISIBLE NOW • LOOK WSW • EL 34°"). CONTROLS (Press START for Tactical Menu): • Simulate Visible Pass: Test a live overhead pass across the Sky Dome and preview the vibration/tone sighting alert anytime. • Sync Live ISS Now: Pulls the latest orbital state vector via Bluetooth and propagates continuously at 1 Hz offline. • Alert Filter: Choose between Optical Sightings Only (naked-eye twilight/night passes) or All Overhead Passes. • Min Elevation: Filter passes by minimum peak elevation (0°, 10°, 20°, or 30°). • Refresh Watch GPS: Update observer coordinates from your watch GPS.

v1.0.0 - Initial Release: • Live Polar Sky Dome Radar with 1-second countdown to the next ISS pass. • 3D Orthographic Earth Globe showing live ISS position, 90-minute orbital track, 2,200 km visibility footprint ring, and user GPS marker. • 24-hour local pass predictor with Optical vs Daytime pass classification. • T-5 minute background watch-face wake alarm and multi-pulse tactile sighting alerts. • Built-in Pass Alert Simulator for instant on-wrist testing.