LSTclock vs SkyChrono

LSTclock is an iOS/iPadOS/watchOS app that displays the local sidereal time (LST) at registered location(s). On iOS/iPadOS, it can also calculate LST and Julian Date for any date and time. The list of locations can be synced between iPhone and paired Apple Watch(es).

SkyChrono is a real-time astronomical dashboard for anyone who plans around the sky—astronomers, astrophotographers, navigators, and curious stargazers. SUN • Live altitude & azimuth • Sunrise, sunset, and solar noon • Civil / nautical / astronomical twilight • Current lighting state (day, twilight, night) + day length MOON • Current phase with illumination % • Moonrise & moonset • Live altitude & azimuth • Phase progression at a glance TIME SYSTEMS • Local time + timezone • UTC • Julian Date (JD) / Modified Julian Date (MJD) • Greenwich Mean Sidereal Time (GMST) • Local Sidereal Time (LST) LOCATION • Automatic GPS position (optional) • Manual coordinates anywhere on Earth • Decimal degrees or DMS input ALERTS & NIGHT MODE • Notifications for sunrise/sunset, twilight boundaries, golden hour, and major moon phases • Night Vision mode (red theme) to preserve dark adaptation EXPORT & LEARN • Save the dashboard as a high-resolution image • Export data as JSON, or copy any value with a tap • Built-in explanations for key astronomy concepts PRIVACY FIRST • No ads, no subscriptions • No tracking—your location stays on device • Manual location mode for complete control SkyChrono helps you pick the right moment—whether you’re planning a shoot, observing, or learning celestial mechanics.