Support for local satellite reference coordinate system

In skyfield I want to calculate alt-az distance from one reference satellite to next (for antenna pointing simulation). My current workaround is to create the reference observer at sat1 height and calculate the alt-az angles:

    sat_observer = sat_ref.subpoint()
    ref_PoV = Topos(sat_observer.latitude, sat_observer.longitude, elevation_m=sat_observer.elevation.m)
    
    satellite = Sat(name)
    orbit = (satellite - ref_PoV).at(time[0])
    el, az, distance = orbit.altaz()

Code is able to calculate relative pointing angles at one time instance. This method is not working for absolute values as the alt-az reference always points to Earth north (the local observer coordinate system at satellite panel will rotate around alt axis in the next time instant).

It would be nice to have support for local coordinate system (LVLH frame) at satellite in skyfield to obtain the alt-az angles respective to this LVLH frame.

Further discussion can be found on stackexchange here.

[matijabrumat]

@brandon-rhodes, I managed to produce the LVLH coordinate frame and calculate the view angles. Minimal working example is published at stackexchange: https://space.stackexchange.com/questions/48796/local-observer-coordinate-system-at-satellite-panel-lvlh-coordinate-system

[brandon-rhodes]

Thanks for the working example, complete with code! I should have time to take a look within the next couple of weeks.