With the advent of electronics in everything, amateur astronomy has never been easier. Telescope mounts that point in the direction of any astronomical object automatically have been around for decades, and the Telrad – a device that paints 0.5, 2, and 4 degree diameter circles in your finder scope’s field of view are available if you’re just too cool for letting a robot do your job. [Christoph]’s explorad takes the concept of a Telrad and adds a somewhat more electronic twist: it still displays the field of view circles, but adds highlighting of interesting astronomical objects from a custom telescope mount, a huge database, and a few sensors.

By far the biggest challenge to any homebrew finder of astronomical objects is figuring out where the observer is. Not only does [Cristoph] need to take into account the location on Earth (GPS helps with that), but also where North is (electronic compass), where the telescope is pointing (optical encoders on a two axis mount), but also the universal time and current sidereal time. Living on a rotating planet that orbits a sun makes for a lot of code.

The current progress on the star finder to beat all star finders is a bit of code that draws the ‘telrad circles’ and displays placeholders for each patch of sky with a small triangle. Tilting the device or turning the azimuth pot moves these triangles and loads new ones on the fly. Now the name of the game is a sky object database for all the astronomical objects [Cristoph] wants to view.