Instruct mount to track objects with non-sidereal motion

[jeremy-taylor]

I discovered when attempting to instruct the mount to follow a satellite that the mount is only issues a single goto instruction and slews only to where an object was when you CTRL+1. It does not make any effort to continue to track the object.

There are many objects including asteroids, comets, the sun, the moon as well as artificial satellites that do not move at apparent sidereal rates and require more than a single command to maintain a central position in the FOV.

Desired behaviour: When you select an object and hit CTRL+1 the telescope moves to the object and then continues to track it. Stars move at a sidereal rate and nothing else needs to be done. Presumably there are solar and lunar tracking rates that can also be specified by command and utilised for tracking the sun or moon, which means the only additional command is the tracking rate. For objects that do not move at sidereal, solar, or lunar rate such as asteroids, comets and satellites: (1) Issue a sequence of commands that permit the object to remain in a given field of view, using a slew-stop/track pause slew-stop/track pattern (and the tracking rate can be any convenient tracking rate supported by the mount) OR (2) [PREFERRED - may only work on certain mounts] Issue a sequence of commands that keeps the object targeted fairly precisely using any of the available ASCOM scope control commands

In https://github.com/Stellarium/stellarium/issues/1128 @gzotti expresses the opinion that attempting to issue multiple slew commands will just torture the drive's motors. I think this perspective presumes that the only commands that could be used would be the targetdeclination and targetrightascension commands. Perhaps we can utilise the pulseguide commands to move the scope in a given direction for a given time and regularly update this to provide a best approximation for the track. There may be other options if we think outside the box, because this is clearly something that can be achieved as SkyTrack by Heavenscape is able to use ASCOM commands to command a mount to track an object using either a leap-frog technique using a series of slew commands or using a rapid-track technique that uses some sort of other strategy, perhaps the pulseguide commands I have suggested above. Given this is apparently feasible by other software, it should be possible to develop similar capabilities for Stellarium.

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[gzotti]

Option 3: Read the fantastic manual and find that RTS2 can track satellites. Install RTS2 and use it... :-)

[jeremy-taylor]

RTS2 seems to be a Linux-only tool, and it would be good to not be dependent on a third party - let's keep this on the wishlist