Polar Alignment Calculator
Find Polaris position for your polar scope and calculate drift alignment error for precise equatorial mount setup.
Location & Time
Polaris Position
How to Use
1. Level Your Mount
Use a bubble level to ensure your tripod and mount are level. This is essential for accurate polar alignment.
2. Point North (or South)
Roughly point your mount's RA axis toward Polaris. Use a compass if needed.
3. Look Through Polar Scope
Find Polaris in your polar scope. It should be near the reticle circle.
4. Position the Star
Adjust altitude and azimuth until Polaris is at the 3 o'clock (right) position on the reticle circle.
Popular Polar Alignment Tools
Why Polar Alignment Matters
The Basics
An equatorial mount rotates around a single axis to track stars as Earth rotates. For this to work correctly, that axis must be aligned with Earth's rotational axis - pointing at the celestial pole.
Poor alignment causes stars to drift in your images, creating elongated or trailed stars instead of pinpoints. The longer your exposure, the more critical alignment becomes.
Alignment Accuracy Guide
- •Visual observing: 1-5° is fine
- •Short exposures (30-60s): 10-15 arcmin
- •Guided imaging: 5-10 arcmin
- •Long unguided exposures: 1-3 arcmin
- •Professional/research: <1 arcmin
Frequently Asked Questions
What is polar alignment?
Polar alignment is the process of aligning your equatorial mount's rotational axis with Earth's rotational axis (pointing at the celestial pole). Proper alignment allows your mount to accurately track celestial objects.
How accurate does polar alignment need to be?
For visual observation, rough alignment within a few degrees is sufficient. For astrophotography with autoguiding, 5-10 arcminutes is acceptable. For unguided long exposures, you need 1-3 arcminute accuracy.
Where is Polaris located in a polar scope?
Polaris is offset from the North Celestial Pole by about 44 arcminutes. Its position on the polar scope reticle changes throughout the night as Earth rotates. Use this calculator to find its current position.
What is drift alignment?
Drift alignment is a technique to achieve precise polar alignment by observing how stars drift over time. By measuring north-south drift of stars near the meridian and east/west horizons, you can calculate and correct alignment errors.
How long does polar alignment take?
Rough alignment: 1-2 minutes. Polar scope: 5-10 minutes. Drift alignment: 20-60 minutes. Electronic tools (PoleMaster/SharpCap): 5-10 minutes.
Complete your imaging setup with: