Local Sidereal Time Calculator U.S Navy Web Site

Local Sidereal Time (LST) is a crucial factor in astronomy and navigation. The U.S. Navy’s Local Sidereal Time Calculator provides accurate, real-time calculations for precise positioning and timing.

1. Enter your latitude and longitude.
2. Select the date and time.
3. Click “Calculate”.
4. Results will appear below the form.

The calculator uses the following formula to calculate Local Sidereal Time:

LST = 4 * (15 * (t – 12) + L) + 180

where t is the local apparent solar time and L is the longitude.

Comparison of Local Sidereal Time and Local Apparent Solar Time

Date	LST (hours)	LAST (hours)

• Always use the most recent data for accurate calculations.
• Consider atmospheric refraction for precise measurements.
• Use this tool in conjunction with other navigational aids.

What is Local Sidereal Time?

Local Sidereal Time is the hour angle of the vernal equinox at a given location and time, measured from the local meridian.

U.S. Naval Observatory’s Sidereal Time Service

Understanding Local Sidereal Time