How well does the Explore Scientific GoTo Tracker Mount track?
That’s a question we often get.
If you ask Chris Hanson of St. Louis, Missouri, USA, he’ll answer with this photo.
This is an UNGUIDED image of Andromeda Galaxy using 305 60-second exposures.
Now, you might think, “Gosh, he’s lucky to live where there’s no light pollution.” In reality, the skies where he lives are Bortle 8-9. The Bortle scale goes from 1 (little to no light pollution) to 9 (inner city – extreme light pollution).
Remember, he did not use a guidescope or camera.
Just the iEXOS-100 GoTo Tracker Mount with careful polar alignment and good balance management.
He captured the image on the night of Aug. 22, 2025.
How does he polar align?
First, he makes sure to have the north leg of the tripod to the north (for our friends in the Southern Hemisphere, it would be to the south).
“I level my mount with a carpenters protractor - the kind where the needle moves freely,” he explained. “I start with Android Polar Aligner Pro, a phone app, to get my rough polar alignment.” Apple iPhones have a similar app named PS Align Pro.
He uses a Move Shoot Move adapter and a small 6-inch dovetail to attach his phone on the mount.
“This typically give me a starting point of about 5-6 arc minutes error. I do this while it’s still light out.
“Next, I make sure I have a near to perfect focus. This speeds up the three-star polar alignment process in NINA. The sharper the stars the faster plate solving runs.”
He follows the guidance of NINA’s three-star polar alignment tool, which allows him to get the polar alignment to less than 5 arc-minutes.
The total process can be done in 15 minutes or less.
How does he balance? Does he use the traditional counterweight heavy and camera heavy? Nope.
“My RA (right ascension) and DEC (declination) balance is near center with no real favor in either direction,” he said. “This seems to give me the best performance.”
He controls the mount using his Windows 11 laptop and USB to establish a very stable serial connection.
He’s found he can quickly get set up for an imaging session, from polar aligning to imaging in a few minutes.
He uses the Explore Scientific Two-Room Pop-Up Observatory Tent for wind management, and to combat his street-level light pollution.
“The iExos-100 is a great mount for mid- to low-weight scopes,” Chris said. “I find the tracking excellent and hardly ever use guiding. The mount movement is very smooth. I can completely recommend this mount.”
IMAGE DETAILS:
Camera: ASI533 MC Pro
Lens / telescope: Sigma 150-600 mm camera lens set at 250 mm with EOS filter drawer adapter.
Filter: Svbony UHC
Software: NINA
Alignment: 3 Point Polar Alignment to 00° 4’34” error
Guiding: None
Sky: Bortle sky 8-9
Moon: None
Exposure: 305 stack of 60-second subs
Processing: Siril 1.4.0-Bata3
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