Astro.Control

C# client library for control of astronomical equipment using remote protocols for interfacing with established astronomical control software including INDI and PHD2.

• Astro.Control
  • INDI
    • Basic Usage
    • Example
      • Satellite Tracking
  • PHD2
    • Basic Usage
  • ASCOM Alpaca
    • Basic Usage

INDI

INDI is a simple XML-like communications protocol described for interactive and automated remote control of diverse instrumentation. A device that includes an INDI server such as Astroberry is required for the code in this libary to interface with. The server actually controls the equipment while a client running this codebase can send instructions to the server.

Basic Usage

1. Connect to the INDI server

var server = new IndiServer("localhost");
IndiConnection conn;
if (server.TryConnect(out conn)) {
    // ...
}

2. Configure connection and assign event listeners (optional)

    conn.Events.OnDeviceFound += (device) => { ... };
    conn.Events.OnPropertyDefined += (device, property, value) => { ... };
    conn.Events.OnPropertyChanged += (device, property, @old, @new) => { ... };
    // ...

3. Poll for devices and their respective properties
   • This task is asynchronous and non-blocking
   • use a listener or delay between querying properties and getting references to devices in order to give the server time to respond.
   • Devices that are not connected to by the server may be missing important properties until connected to

    conn.QueryProperties();

4. Fetch device's reference to manipulate its INDI properties

    IndiDevice device;

    // Fetch a specific device by its known name
    device = conn.Devices.GetDeviceByNameOrNull("Celestron GPS");
    // Fetch a device by its known properties, can use these to determine the "type" of device
    device = conn.Devices.AllDevices().Where((d) => d.Properties.Exists("TELESCOPE_INFO")).FirstOrDefault();

5. Connect the device on the INDI server if it is not already connected.
   • this can trigger more properties to be pulled as not all devices publish all properties until the device is connected.
   • The AutoConnectDevices property of an IndiConnection can automatically do this when connectable devices are discovered.

    // Connect a single device
    device?.Connect();
    // Connect all devices on the server
    foreach (var d in conn.Devices.AllDevices())
        d?.Connect();

6. Manipulate the device using a controller to abstract away the manipulation of the device properties

    if (device != null) {
        var telescope = new IndiTelescopeController(device);
        telescope.SetSlewRate(SlewRate.Max);
        telescope.StartRotating(Direction.North);
    }

Example

Satellite Tracking

// Connect to the server
var server = new IndiServer("localhost");
IndiConnection conn;
if (!server.TryConnect(out conn)) {
    throw new Exception("Failed to connect to the INDI server");
}

// Wait for device to be received by the client
var driver = "Telescope Simulator";
var device = conn.Devices.GetDeviceByNameOrNull(driver);
var retries = 10;
while (retries > 0 && device == null) {
    Thread.Sleep(TimeSpan.FromSeconds(0.5));
    device = conn.Devices.GetDeviceByNameOrNull(driver);
    retries--;
}
if (device == null) {
    throw new Exception("Could not find device driver");
}

// Make sure it is connected
retries = 10;
while (retries > 0 && !device.IsConnected) {
    device.Connect();
    Thread.Sleep(TimeSpan.FromSeconds(0.5));
    retries--;
}
if (!device.IsConnected) {
    throw new Exception("Failed to connect device driver");
}

// Use satellite ephemeris to compute ra & dec relative to observer (another library)
Angle ra = ...;
Angle dec = ...;

// Tell the telescope to track the coordinates
var controller = new IndiTelescopeController(device);
controller.Track(ra: ra, dec: dec, rate: TrackingRate.Sidereal);

// Satellites are fast, optionally recompute the RA and DEC and goto the new coordinates
var tracking = true;
while (tracking) {
    Thread.Sleep(TimeSpan.FromSeconds(1));
    ra = ...;
    dec = ...;
    controller.Track(ra: ra, dec: dec, rate: TrackingRate.Sidereal);
}

PHD2

PHD2 is a telescope guiding software for providing small and continuous adjustments to telescope mounts in order to keep a target imaging area as stable as possible for longer exposure imaging. It is known for its simplicity and ease of use. PHD2 includes a server mode and uses a JSON schema to communicate with a client library such as this one.

Basic Usage

1. Connect to the PHD2 server

var server = new Phd2Server("localhost");
Phd2Server conn;
if (server.TryConnect(out conn)) {
    // ...
}

2. Configure connection and assign event listeners (optional)

    conn.Events.OnAppStateChanged += (state) => { ... };
    // ...

3. Call RPC methods to interact with the PHD2 server

    conn.Guide();

ASCOM Alpaca

ASCOM Alpaca is a rest based service used for cross platform control and monitoring of devices controlled via the ASCOM platform.

Basic Usage

1. Connect to the Alpaca server

var server = new AscomAlpacaServer("localhost");
AlpacaConnection conn;
if (server.TryConnect(out conn)) {
    // ...
}

2. Obtain device

var telescope = conn.EnumerateTelescopes().First();

3. Send remote control commands

telescope.Track(ra: Angle.Hours(0), dec: Angle.Degrees(41), TrackingRate.Sidereal);