Astro Clock

The instructions are missing the Milky Way tab, the date/time scrubber, and the GeoLog paste tip. Here’s the corrected version to replace the existing description block at the top of the page:


Sun tab — Sunrise, solar noon, and sunset for the selected date in your local time. A live progress bar shows where the sun currently sits in its arc, with the sun icon tracking its position and switching to a dark circle when below the horizon. Current altitude and azimuth with compass direction. Golden hour windows (morning and evening), blue hour windows, and a twilight table showing civil, nautical, and astronomical twilight times.

Moon tab — Live phase name with illumination percentage, age in days, and current altitude and azimuth. An SVG moon disc renders the actual illuminated fraction with correct waxing and waning geometry. Next new moon and next full moon dates with a days-until countdown.

Milky Way tab — The galactic plane arc plotted on a live 360° sky chart for your location and time. The galactic core is marked with a glowing indicator. The chart shows the sun and moon positions, colors the sky based on darkness level (daylight through astronomical darkness), and updates every second. Data cards show the visibility rating, moon interference level, sky condition, and galactic core rise, transit, and set times. A season bar across the bottom shows which months offer the best core visibility from the northern hemisphere.

Sidereal tab — Local Sidereal Time live to the second — the right ascension currently crossing your meridian, useful for telescope pointing. Also shows Greenwich Mean Sidereal Time, current UTC, and live Julian Date and Modified Julian Date.

Julian Date tab — Links to the Julian Date Converter tool.


Location — The tool requests your location automatically on load. If you decline or want to use a specific spot, enter latitude and longitude manually and click Set. If you copy coordinates from GeoLog, you can paste the full pair — for example 43.165475, -70.592758 — directly into the Latitude field and the tool will split them automatically.

Date and time scrubbers — Two sliders sit above the tabs. The Date slider scrubs up to a year forward or back so you can plan a shoot on any night of the year. The Time slider locks the calculations to a specific UTC hour so you can see exactly what the sky looks like at midnight, 2am, or any other time. The Now button returns the time slider to live mode. All tabs respond to both sliders.

24hr / 12hr toggle — Switches all time displays across all tabs.

No ads. No fees. No signup. Just a tool that works.


Astro Clock

Astro Clock

// sun, moon, sidereal time — real-time astronomical data for your location — no signup, no paywall, ever

No location set
Calculated for: —
Waiting for location
Date Today
Time Now
Today
Sunrise
Solar Noon
Sunset
Day Length
SunriseSunset
Current Position (local)
Altitude
Azimuth
Golden Hour & Blue Hour
🌜 Blue Hour (morning)
Golden Hour (morning)
Golden Hour (evening)
🌜 Blue Hour (evening)
Twilight
TypeMorningEvening
Civil (−6°)
Nautical (−12°)
Astronomical (−18°)
Current Moon
Phase
Illumination
Age
Altitude
Azimuth
Upcoming Phases
🌑 Next New Moon
🌕 Next Full Moon
Sidereal Time
Local Sidereal Time (LST)
Right ascension currently on your meridian

Greenwich Sidereal Time (GMST)
UTC
Julian Date
JD (now)
MJD (now)

The sidereal day is 23h 56m 4.09s — about 3m 56s shorter than a solar day. Earth completes one full rotation relative to the stars in this time.
Visibility Now
Rating
Sky Condition
Sun Altitude
Moon Phase
Moon Impact
Galactic Core Today
Altitude
Azimuth
Rises
Transit
Sets
Core Visibility by Month (Northern Hemisphere)
■ Dark = not visible   ■ Teal = rising season   ■ Green = prime season (Jun–Aug)

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