ELink

An astronomy control stack in the spirit of Ekos and N.I.N.A., built differently: every piece of equipment, every smart scope and the UI is an endpoint on EVent, a distributed event/dRPC mesh. C# / .NET 8, Avalonia UI, INDI for the hardware.

Status: early. Everything below runs and is tested against the INDI simulators (240 automated tests, including a headless run of the whole UI), but it has not yet had a night on real hardware. Expect rough edges.

The idea

• One request: "this image of this part of the sky." An area (a single frame is just a small one), a depth and an output pixel scale. Any number of scopes pull work from it, each with its own cameras, and a live stack of all their frames is the image. There is no separate mosaic mode and no keeping scopes in sync.
• Autonomous smart scopes. Guiding, dithering, centring after slews, autofocus triggers, meridian flips, cooling and frame grading all live inside the scope. Nothing above it coordinates them.
• Flexible composition. An imaging train is one optical path: optics, imaging cameras, an off-axis guider, filter wheel, focuser, rotator. A smart scope carries any number of trains on a mount and guides with whichever train or OAG camera you assign. Scopes are Pointers and Shooters themselves, so they nest.
• Nothing references anything else. Modules share only contract types and IDs (src/ELink.Contracts), all messages are binary NOTES types (no JSON over the wire), and a test enforces that the UI never references a backend. The UI can run in its own process on another machine.
• Standard INDI. Mounts, cameras (DSLRs too), focusers, wheels, rotators, domes, weather and GPS are driven through the standard INDI properties, the same ones Ekos uses, so no vendor SDKs are involved.

Features

Imaging	area filling shared between scopes, dither on every shot, resume across nights under the image's name
Scheduler	queue of images with priorities, altitude/horizon, darkness, Moon distance and brightness, time windows; carries on night after night
Live stack	sky registration (WCS, plate solve or pointing) into a fixed field at any pixel scale, debayering (interpolated or super pixel), outlier rejection, flux matching across cameras, one stack per filter, dark/flat calibration
Calibration	master darks, biases and flats per camera; flats find their own exposure; matched by exposure, gain, temperature, binning, filter
Guiding	multi-star guider in each scope, PHD2-style calibration over INDI pulse guiding, dither and settle, or "you are here, should be here" corrections for devices that close the loop
Focus	HFR autofocus; triggers per train (start, time, temperature, filter, star growth); per-filter offsets
Pointing	plate solving (ASTAP and/or astrometry.net), centring by aim-off, learned pointing correction, meridian flip
Cameras	gain/offset presets, slow cooling ramps with the scope waiting until cold, frame grading (clouds, trailing, soft focus)
Sky	atlas from KStars data plus OpenNGC and GSC, site and twilight, Sun/Moon/planets, horizon profile, Stellarium bridge
Equipment	equipment profiles (ELink runs the INDI drivers itself and restarts a dying server), raw INDI property browser

Quick start

Requirements: Linux, the .NET 8 SDK, and INDI (indiserver and drivers). Optional: KStars' sky data (for the atlas), ASTAP with a star database and/or astrometry.net's solve-field (for plate solving).

git clone https://github.com/UltraGeekDEV/ELink-Astro.git
cd ELink-Astro
./dev.sh build

Try it on the simulators:

indiserver indi_simulator_telescope indi_simulator_ccd indi_simulator_wheel indi_simulator_focus &
dotnet run --project src/ELink.Station -- --indi localhost:7624

With your own rig, list its drivers once under Rig › Drivers and start them from there (or elink --profile NAME): ELink runs its own indiserver. The bridge and the UI can also run as separate processes on one mesh:

dotnet run --project src/ELink.Bridge -- --indi localhost --port 5698
dotnet run --project src/ELink.App -- --host 127.0.0.1 --port 5698

Then connect your equipment and set up a telescope and a scope under Rig, and ask for an image on the Sky: pick a target, press Frame this, drag the frame where you want it, press Start. The status strip along the top says what is still to set up.

Documentation

• User guide: the five views, the picture page, setting up a rig, imaging an area, troubleshooting.
• Developer guide: architecture and the design spec, patterns, IDs, adding devices and services, testing.
• Roadmap.

Layout

project	what
ELink.Contracts	NOTES types and IDs: equipment, Pointer/Shooter/Scope/Train, automation services
ELink.Core	node helpers, RemoteState, StatePublisher, Commands, astro math
ELink.Indi	INDI XML protocol client with a live property model
ELink.IndiBridge	INDI ↔ EVent: a generic mirror of every property, typed adapters per device kind, equipment profiles
ELink.Compose	smart scopes, imaging trains, mount pointers, camera shooters, guiders, the composition host
ELink.Imaging	FITS, TAN WCS, live stacker, debayering, star detection and HFR, frame grading, calibration
ELink.Automation	image requests, scheduler, autofocus, plate solving, centring, live stacking, calibration library, storage, site
ELink.Atlas / ELink.Stellarium	sky atlas service; Stellarium telescope server and Remote Control client
ELink.UI / ELink.App	Avalonia UI and its stand-alone executable
ELink.Bridge / ELink.Station	headless INDI bridge; all-in-one elink (bridge, services and UI on one node)

EVent is not on nuget.org; it lives in EVent/ and its packages are in EVent/nuget/ (a local feed, see nuget.config).

Developing

./dev.sh build|test wraps dotnet without resident build servers (they pile up and eat gigabytes of RAM). The integration tests start real indiserver simulators in a throwaway HOME and are skipped when INDI is not installed; plate-solve tests run when a solver is found.

License

GPL-3.0, the same family as KStars/Ekos.