Telescope autoguiding & automation with a Raspberry Pi

Work in progress — automating and guiding my Celestron C8 on an EQ6-R Pro mount with a Raspberry Pi and Astroberry, an ASI120MM Mini guide camera and Ekos.

Status: in progress. A build log I update as the rig comes together.

The goal

Turn my telescope into a remotely controlled, autoguided astrophotography system: slew, focus, align and track deep-sky objects without standing at the eyepiece, with the mount corrected in real time from the guide camera.

The gear

• Optics: Celestron C8 EdgeHD — 2032 mm f/10.
• Mount: Sky-Watcher EQ6-R Pro SynScan, driven directly by the Pi over an EQDIR cable (no handset). It replaced an AVX that had become the bottleneck — with ~25 kg capacity there’s plenty of headroom now.
• Brain: a Raspberry Pi 4 running Astroberry, the Linux distro built for astrophotography (KStars/Ekos + INDI out of the box).
• Guiding: a ZWO ASI120MM Mini (mono) on an SVBony SV165 guide scope (30 mm f/4, 120 mm focal length) → a field of ~2.3°×1.7° and a scale of about 6.4”/px, so there’s always a guide star to lock onto.
• Imaging: a colour ASI120MC for planetary/lunar at the C8’s focus (with a 2× Barlow, lucky imaging) and, later, a Canon DSLR for deep sky.

How it works

The Raspberry Pi runs Ekos/KStars (on INDI): from there I drive the mount, cameras, focusing, plate solving and autoguiding. The mount responds directly over EQDIR (the EQMod protocol), with no handset. The guide camera streams continuously, the software measures how the stars drift and sends the mount tiny corrections to keep the target pinned on the sensor for the whole exposure.

It all happens remotely from my Mac, over SSH for commands and a remote desktop (VNC) for the GUI — so I can run the night comfortably from indoors.

Where I’m at

• ✅ Direct mount control over an EQDIR cable (no handset; the mount’s built-in USB-B port is faulty, but that’s now irrelevant). Phase 1 hardware is complete.
• ✅ Cameras recognised in Ekos, with the guide optical train configured (30 mm / 120 mm).
• ✅ Remote access stable (SSH + VNC from the Mac).
• ✅ Plate-solving index files (astrometry.net) already downloaded — StellarSolver, fully offline.
• 🔧 What’s left is the software configuration and the first clear night: the first Capture & Solve, then assisted polar alignment.

Power

To use it away from the garden I’ve gone with a ~256 Wh LiFePO4 power station: at a ~30 W draw it gives around 6 hours of runtime and powers the mount, a USB hub, the Raspberry Pi and the cameras from a single box, with a built-in charge display. I’d designed a DIY power box, but the power station turned out simpler and cheaper. A small USB GPS dongle provides time and location in the field, since the Pi has no real-time clock.

A typical night

Assemble and balance, home position, then almost everything from software: the GPS fills in time and location, Ekos’s assisted polar alignment guides the knob corrections, and for each object a GoTo + Capture & Solve centres the target using plate solving. Planets with the ASI120MC and the 2× Barlow, deep sky (in future) with the Canon. At the end of the night: park the mount and shut the Pi down cleanly.

Next steps

1. Configure the GPS in Ekos (automatic time and location).
2. First clear night: first Capture & Solve and assisted polar alignment.
3. First real autoguiding runs on the deep sky.
4. Planetary imaging with the ASI120MC + 2× Barlow.
5. (Phase 2) a focal reducer and Canon control via gphoto2 for deep sky.

I’ll update this page at each milestone. 🔭