1. What is Current Sidereal Time?

Local Sidereal Time (LST) is the hour angle of the vernal equinox, representing the right ascension of objects currently crossing the local meridian. It's calculated by adjusting Greenwich Sidereal Time (GST) for the observer's longitude.

2. How Does the Calculator Work?

The calculator uses the simple formula:

Where:

• \( \text{GST} \) — Greenwich Sidereal Time in hours
• \( \text{Longitude adjustment} \) — Observer's longitude converted to hours (15° = 1 hour)

Explanation: The formula accounts for the Earth's rotation and the observer's position east or west of Greenwich.

3. Importance of Sidereal Time

Details: Sidereal time is crucial in astronomy for telescope pointing, celestial navigation, and astronomical observations. It helps determine which celestial objects are currently visible.

4. Using the Calculator

Tips: Enter GST in hours (0-24) and longitude adjustment in hours (positive east, negative west of Greenwich). The result will be normalized to 0-24 hours.

5. Frequently Asked Questions (FAQ)

Q1: How do I convert degrees to hours for longitude?
A: Divide longitude in degrees by 15 (since 15° = 1 hour). East longitudes are positive, west are negative.

Q2: What's the difference between sidereal and solar time?
A: Sidereal time is based on Earth's rotation relative to distant stars (23h56m per rotation), while solar time is based on rotation relative to the Sun (24h per rotation).

Q3: How accurate is this calculation?
A: This provides basic LST calculation. For precise astronomical work, additional corrections may be needed for precession, nutation, and polar motion.

Q4: Where can I find current GST?
A: Current GST can be calculated from UT1 or obtained from astronomical almanacs and some planetarium software.

Q5: Does this account for daylight saving time?
A: No, sidereal time calculations are independent of time zones and daylight saving adjustments.