What is a guidescope?

BBC Sky at Night Magazine's Scope Doctor Steve Richards solves your practical astronomy ailments.

Telescope finderscopes are a great way of locating celestial objects for a closer look. Read our reviews of the latest finderscopes.

What is a guidescope?

Steve says: “A guidescope is used to correct for small errors in a mount’s tracking.

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The guidescope is a small refractor or even a modified finderscope that is mounted along with the imaging telescope and camera and its job is to capture an image of a single star using its own small camera and then to analyse the movement of that star in the field of view using guiding software.

If the star moves, the software sends corrections to the mount to ‘keep it on track’. Because the guidescope and imaging scope are mounted together, corrections in the guidescope produce matching corrections in the imaging scope.”

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Email your astronomy queries to Steve at scopedoctor@skyatnightmagazine.com and they could get answered in a future issue of BBC Sky at Night Magazine.