OnStep Controller - GDA

OnStep Controller

Take full control of your OnStep telescope mount from your iPhone. OnStep Controller is a clean, dark-mode companion app for amateur astronomers — connecting over WiFi (OnStep or OnStepX) or Bluetooth Low Energy (OnStepX with the BLE plugin required) to give you everything you need from setup to the final star.

Connect and Configure
Connect to your mount over your local WiFi network or via Bluetooth Low Energy. Send your GPS coordinates and current time directly to the mount for accurate alignment, and verify that the mount's site data matches your device before you start observing.

Interactive Sky Chart
Browse a live star chart showing hundreds of named stars and Messier deep-sky objects projected for your exact location and time. Pan and zoom freely, then tap any object to see its details and issue a GoTo command. Horizon, overhead, and meridian flip limits are drawn directly on the chart so you always know what your mount can reach.

Visual Star Alignment
Begin a 1- to 9-star alignment from the Setup tab and get guided through the process on the sky chart. Pick your alignment stars visually, slew to each one, then fine-tune with the on-screen directional pad and accept.

Full Mount Control
Move the mount in any direction at four slew rates — Guide, Center, Find, and Slew. Toggle tracking on and off, switch between Sidereal, Lunar, and Solar tracking rates, park and unpark, and find home — all from a single screen with live RA, Dec, Alt, and Az readouts.

GoTo from a Catalog
Search a built-in catalog of stars, open clusters, globular clusters, nebulae, galaxies, and planetary nebulae. Filter to objects currently above the horizon and slew to any target with a single tap. Or enter coordinates manually for objects not in the catalog.

Designed for the Dark
The entire app runs in forced dark mode with a deep red accent color chosen to protect your night vision at the eyepiece.

Requires an OnStep or OnStepX telescope mount controller. WiFi works with both; Bluetooth requires OnStepX with the BLE plugin installed. iOS does not support Classic Bluetooth.