What EKOS is
EKOS is an astrophotography and observatory control tool that is shipped with KStars, the free planetarium software from the KDE project. It brings the common imaging tasks into one program: pointing the telescope, plate solving, focusing, guiding, polar alignment, capturing images and scheduling a session. It supports Windows, macOS and Linux, though how well each platform handles directly connected equipment differs (see below).
How EKOS, KStars and INDI fit together
Three pieces are involved.
- KStars is the planetarium and sky map. It provides target selection and framing.
- EKOS is the control layer inside KStars that runs the imaging modules.
- INDI is the open device-control framework that talks to mounts, cameras, focusers, filter wheels and other equipment through drivers.
You select drivers in an equipment profile, start the INDI server, connect, and then use EKOS to operate the devices. Profiles let you keep separate configurations, for example one for a home setup and one for a remote rig.
The main modules
- Capture: (works with a DSLR as in astrophotography with a telescope and DSLR) single exposures and a sequence queue with filters, exposure times and file naming. Sequences can be saved and loaded.
- Focus: automatic and manual focusing, based on half-flux radius (HFR). It can refocus when HFR drifts past a limit you set. Our article on FWHM in astronomy covers a related star-size measure.
- Align: plate solving using astrometry.net, either online or offline, for accurate GoTo and for the Polar Alignment Assistant (background in how to polar align a telescope).
- Guide: a built-in guider (see astrophotography with a telescope for why guiding matters), with support for dithering between exposures, or connection to an external guiding program.
- Mount: slewing, tracking (telescope tracking explained) and meridian flip control.
- Scheduler: chooses targets and runs sessions automatically within constraints you define.
- Observatory and Analyze: dome and roof control, and session analysis tools in newer versions.
Features and names evolve between releases, so check the current KStars documentation for specifics.
A typical first-session setup
- Install KStars and set your location and time.
- Create an equipment profile with your mount, camera, focuser and other drivers.
- Start INDI and connect your devices.
- Set up plate solving in the Align module.
- Run equatorial mount setup and polar alignment, then slew to a target and confirm with a solve.
- Focus, start guiding, and set up a capture sequence with dithering.
- Optionally build a schedule for unattended runs.
Take it one step at a time. Many people start with simple captures and add automation later.
Platforms and hardware
Linux is the most common home for EKOS with directly attached equipment, and many users run it on a small single-board computer or a mini PC at the telescope, controlled remotely over a network with a remote desktop tool. Some users of other platforms run EKOS as a remote client instead. Support varies by version, so check current documentation before buying hardware. Commercial products such as StellarMate package this idea into a ready-made controller.
EKOS vs NINA
NINA is a popular Windows-based alternative. In one user comparison on Cloudy Nights, the author rated the two as close, preferring EKOS for its clear interface and integration with the KStars planetarium for framing, and NINA for its sequencer and some alignment and focus features. That is one person’s experience, and both programs change often. In general terms:
- EKOS suits people who like Linux, open-source tools and a built-in planetarium.
- NINA suits people who prefer Windows and its ASCOM ecosystem and a more elaborate sequencer.
Try both if you can, and pick the one whose workflow you find easiest to trust at night.
Who EKOS suits
EKOS is a good fit if you want an integrated, free tool and are comfortable with some configuration. Beginners may find the first setup involved, so budget time for a daytime dry run with the equipment indoors.
After capture
EKOS handles gathering the data. Calibration, stacking and finishing are done in other software. If you process in PixInsight, our guide to star reduction in PixInsight is a good next read.