Even the best telescope mount is only as good as its ability to track celestial objects accurately. Whether you’re preparing for astrophotography or long-duration observation, testing tracking performance is a straightforward but necessary task. You don’t need a high-end lab—just a clear sky, some basic gear, and attention to detail.
Why Tracking Accuracy Matters
Without proper tracking, stars turn into streaks, planets blur, and nebulae vanish from the frame. Even small errors compound during long exposures. Testing your setup at home lets you correct issues before you miss out on an astronomical event or produce unusable images.
What You’ll Need
- Your telescope and mount
- A reticle eyepiece or high-power eyepiece (10mm or lower)
- A steady tripod or pier
- A known celestial object (star, planet, or the Moon)
- Notepad or tracking app
- Access to an online timer
Step 1: Level and Polar Align Your Mount
Accuracy begins with alignment. For equatorial mounts, polar alignment is non-negotiable. Use Polaris or a polar scope to get as close as possible. Alt-azimuth mounts require leveling and proper initialization procedures.
Quick Alignment Tips:
- Use a bubble level on the tripod legs.
- If you don’t have a polar scope, a smartphone app with a compass and inclinometer can assist.
- Do not rush alignment. Small misalignments can lead to large errors during testing.
Step 2: Choose the Right Star for Testing
Select a star near the celestial equator. Stars in this region move the fastest across the sky, making them ideal for evaluating tracking accuracy. Avoid objects close to the horizon to minimize atmospheric distortion.
Ideal targets:
- Betelgeuse (Orion)
- Sirius (Canis Major)
- Altair (Aquila)
Aim for a magnitude that’s bright but not too overwhelming—around magnitude 1 to 3.
Step 3: Center and Monitor the Star
Place the chosen star in the center of your eyepiece. If you’re using a reticle eyepiece, even better—you’ll have crosshairs for precision. Activate tracking on your mount and start observing.
This is where your online timer becomes useful. Set it for 5 to 10 minutes. Your task is to see how far the star drifts from center over that period.
Step 4: Log the Drift
As the star moves, jot down or record:
- Time elapsed
- Direction of drift (RA or DEC)
- Speed of drift (approximate or in mm on your eyepiece)
- Quality of the star’s appearance (focus, shape, etc.)
Repeat this test with different stars in different parts of the sky. North, South, East, and West each stress the mount in different ways.
Step 5: Analyze the Error Sources
Tracking errors usually come from one or more of the following:
Periodic Error
- Caused by imperfections in the gear teeth of the RA drive.
- Typically repeats every 5–10 minutes.
- Solution: Use PEC (Periodic Error Correction) if your mount supports it.
Polar Misalignment
- Results in drift mostly in Declination.
- Fix by redoing your polar alignment carefully.
Gear Slop or Backlash
- Happens when the gears take time to “catch” after reversing direction.
- Common in cheaper or older mounts.
- Solution: Tighten gears or adjust balance.
Balance Issues
- If your scope is front- or rear-heavy, motors will strain to maintain alignment.
- Always balance RA and DEC axes with counterweights and accessories attached.
Step 6: Adjust and Repeat
After identifying problem areas, tweak your mount settings, alignment, or balance. Run the same test again to compare results.
Optional Step: Use a Camera for Drift Logging
If you have a planetary camera or DSLR, try shooting short exposures during tracking. Stack them later and measure star movement frame by frame. Software like PHD2 or SharpCap can automate this analysis.
Additional Tips to Improve Tracking
- Run your mount with fresh power—low voltage can reduce motor accuracy.
- Lubricate moving parts if your mount hasn’t been serviced in a while.
- Keep the tripod on a firm surface. Even small ground shifts can alter results.
- If you’re testing in winter, allow the mount to thermally acclimate before running tests.
Common Questions
How often should I test tracking?
After any transport, firmware update, or realignment. It’s also wise before any major astrophotography session.
Do all mounts require periodic error correction?
No. High-end mounts have factory correction or low intrinsic error. Budget mounts benefit significantly from PEC or guiding.
Can guiding replace good tracking?
Not really. Autoguiding is a patch—not a cure. If the base tracking is unstable, guiding will struggle to correct it.
Summary Checklist
Before Testing
- Mount leveled
- Polar aligned
- Proper star selected
During Testing
- Use high-power eyepiece
- Center star and run timer
- Observe drift and log details
After Testing
- Adjust alignment, balance, or settings
- Re-test and compare logs
Testing tracking at home builds your confidence and prevents wasted nights under the stars. Reliable tracking separates a decent telescope session from a successful one. If you’re selling or buying used equipment, proving or verifying tracking performance can also boost trust and value.