Tooling
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Mount & Session Control

KStars/Ekos, INDI, N.I.N.A, ASCOM/Alpaca — drive the scope, sequence the night, log everything.

The "make the mount go to a target, focus, plate-solve, dither, take 60 × 5-minute subs while I sleep" tier. Three software stacks own this category in 2026: KStars/Ekos + INDI (cross-platform OSS), N.I.N.A (free Windows / ASCOM), and TheSkyX / Voyager (paid, observatory-grade). The driver standards underneath — ASCOM, INDI, and the newer Alpaca — are how everything talks to everything.

For finding what to point at see Planetariums & Sky Maps; for the autoguiding loop see Autoguiding; for figuring out where the scope actually points see Plate Solving; for running it all on a Pi at the scope see Pi-based Astro Control; for OSS mount firmware see OnStep & DIY Mount Firmware; for the SBCs underneath see AI / NPU SBCs and Classic Pi Projects.

Free / OSS suites (cross-platform)

  • ★ ★ KStars + Ekos — GPL, Win/macOS/Linux + ARM. KStars is the planetarium; Ekos is the bundled astrophotography session manager: capture, focus, mount alignment, polar align, plate solve, autoguide (via PHD2 or built-in INDI guider), schedule, meridian flip, dithering, automatic dark/flat libraries, observation logging. The whole stack is OSS and runs on a Raspberry Pi at the scope or on your laptop. The 2026 OSS reference; effectively a free Voyager-equivalent for most setups.
  • ★ ★ INDI (Instrument Neutral Distributed Interface) — GPL device server. Drivers for ~150 mounts, cameras, focusers, filter wheels, dome controllers, weather stations, GPS — anything with an astro driver on Linux/Mac. Ekos talks to it; so do StellarMate, Astroberry, third-party clients (CCDciel, KStars, Stellarium). The Linux/Mac astro plumbing layer.
  • CCDciel — free Lazarus/Pascal capture/sequencer that talks INDI or ASCOM; minimalist alternative to Ekos for people who only need acquisition.
  • AstroDMx Capture — free cross-platform capture; lighter than Ekos; popular for planetary / lunar.

Free Windows suite

  • ★ ★ N.I.N.A (Nighttime Imaging 'N' Astronomy) — MPL-2.0, Windows only. The 2024–2026 community favorite for free Windows acquisition: visual sequencer (Advanced Sequencer), framing assistant, 3-Point Polar Alignment, plate solving via ASTAP / Astrometry / PlateSolve2, autofocus, meridian flip, dithering with PHD2, plug-in marketplace (Hocus Focus, Touch'N'Stars, Sky Atlas, Ground Station / MQTT). Free; donation-funded; has eclipsed Sequence Generator Pro for hobbyists.
  • APT (AstroPhotography Tool) — paid (~$25 perpetual) but has a free unrestricted trial. Older, simpler than N.I.N.A; still loved by some. Sliding into legacy in 2026.
  • Backyard EOS / Backyard Nikon — paid (~$50). DSLR-tethered capture with planetarium / dithering / framing. The pick if you're doing DSLR-only astrophotography on Windows. See Photo Tethered Shooting for non-astro DSLR tether tools.
  • Sequence Generator Pro (SGP) — paid (~$100). Long the Windows pro pick; superseded by N.I.N.A for most users in 2026 but still excellent and actively maintained.
  • ★ Voyager (Starkeeper) — paid (~€350 perpetual + annual maintenance). Robotic-observatory-grade Windows automation; "DragScript" flow language, multi-night campaigns, advanced safety/sensor integration. The choice when you have a roll-off-roof at altitude and care about uptime.
  • TheSkyX Pro + Camera Add-On (Software Bisque) — paid (~$400 + $200). Mature; mount support is best-in-class; observatory automation strong. Also a planetarium — see Planetariums.
  • MaxIm DL Pro — paid; venerable; less common in 2026 but still around.
  • Prism v11 — paid French suite; popular in Europe.
  • ACP Observatory Control — paid; the highest-end commercial option (remote observatory management).

Driver standards (the protocol layer)

  • ★ ASCOM (Astronomy Common Object Model) — Windows-only COM-based driver standard since 1998. Free (LGPL platform). Every Windows astro app talks to mounts/cameras/focusers via ASCOM. If you're on Windows, ASCOM is the stack — see https://ascom-standards.org.
  • ★ INDI — the Linux/Mac/Pi equivalent; client–server protocol with a TCP transport, so the device server can run on a Pi and the client on your laptop. KStars/Ekos is the dominant client.
  • ★ Alpaca — ASCOM's modern HTTP/JSON cross-platform sibling (2019 spec, mature in 2024–26). Cross-platform — Mac, Linux, iOS, Android can finally talk to ASCOM-style devices over a network. Most modern astro hardware now ships an Alpaca server (e.g., ZWO Alpaca, PrimaLuceLab Eagle). The 2026 direction of travel; Linux-side drivers via INDI are gradually exposing Alpaca shims as well.

Pi / SBC-based all-in-one stacks

See Pi-based Astro Control for full coverage. Short version:

  • ★ StellarMate OS — paid (~$50 OS + optional preinstalled Pi hardware ~$300). Pi-flashable distro of KStars + Ekos + INDI; web UI; the polished commercial Pi-based controller.
  • ★ Astroberry — free; Debian + Ekos/INDI + VNC; the OSS DIY equivalent.
  • ★ ZWO ASIAIR Plus / Pro / Mini — closed proprietary Pi-based controller from ZWO; pairs with the ASIAIR mobile app. Free with ZWO hardware; only works in the ZWO ecosystem (their cameras / filter wheels / EAF focuser, plus a whitelist of supported third-party mounts). Wildly popular; closed. For a fully open alternative use Astroberry or StellarMate.

Mount-specific control

For the firmware running inside the mount itself see OnStep & DIY Mount Firmware. Software-side, common mount-only controllers are:

  • ★ EQMOD / EQASCOM — free ASCOM driver for SkyWatcher / Orion synta-protocol mounts (HEQ5, EQ6, AZ-EQ, EQ8). Dethrones the hand controller and exposes everything to PC. The de-facto SkyWatcher-on-Windows driver; free.
  • GS Server — newer SkyWatcher ASCOM driver; slicker UI than EQMOD; free.
  • SynScan App — SkyWatcher's own mobile/desktop app; free; less feature-rich than EQMOD.
  • CelestronMobile / CPWI — free Celestron apps (Celestron PWI is the better one).
  • iOptron Commander — free iOptron tool.
  • Software Bisque Paramount — uses TheSkyX as front-end; paid mount.

What's changing in 2024–2026

  • N.I.N.A 3.x ascendancy — has overtaken SGP and APT for free Windows; plug-in ecosystem is on fire. Free.
  • Alpaca momentum — most new gear ships Alpaca alongside ASCOM/INDI; the cross-platform driver story is finally getting good.
  • Ekos scheduler maturity — multi-night, multi-target sequencing rivals Voyager DragScript for many use cases; OSS.
  • ASIAIR closedness pushback — ZWO removed support for some non-ZWO devices in 2023; OSS alternatives (StellarMate, Astroberry, INDI) gained share.
  • Touch'N'Stars / mobile UIs — Tablet/phone web-UIs over the top of N.I.N.A and Ekos for "control from inside the warm car".

License / pricing summary

  • Free / OSS: KStars + Ekos, INDI, N.I.N.A, CCDciel, ASCOM platform, Alpaca, EQMOD, GS Server, Astroberry.
  • Paid (~$25–$100): APT, SGP, Backyard EOS/Nikon, StellarMate OS.
  • Paid (~$300–$500): TheSkyX Pro, Voyager, Prism, MaxIm DL.
  • Paid hardware-bundled: ZWO ASIAIR (free with ZWO cameras), PrimaLuceLab Eagle (~$1500 Pi-with-software-tax), Pegasus PowerBox.

Pick this if…

  • One free cross-platform suite, runs on a Pi: KStars + Ekos (with INDI underneath).
  • One free Windows suite: N.I.N.A.
  • All-in-one ZWO ecosystem, easy mode: ASIAIR.
  • OSS Pi-side equivalent of ASIAIR: StellarMate (paid OS) or Astroberry (free).
  • Robotic observatory, money no object: Voyager or TheSkyX Pro.
  • DSLR only, Windows: Backyard EOS / Nikon.
  • You write software and want to drive a mount from anything: target Alpaca; INDI on Mac/Linux; ASCOM on Windows.

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