Piggyback — a second imaging train on one mount
Piggyback mode runs a follower imaging train (its own camera, focuser and filter wheel) alongside your lead train on the same mount — two scopes imaging in tandem. The public edition supports one follower; more trains is a Professional feature.
Piggyback is off by default, and with it off Starship behaves exactly like a normal single-rig setup — nothing changes.
What the follower shares vs. owns
The follower rides on the lead's mount, so it has no mount and no guider of its own — the lead owns pointing, dithering and meridian flips. The follower brings its own camera + focuser + filter wheel, and images whatever the mount is currently pointing at, using its own filter, exposure, cooling and refocus cadence.
The safety rules (automatic)
Everything that touches the shared mount is coordinated so the two trains never step on each other:
- No frame straddles a mount move. A follower exposure won't start while a
slew / flip / dither is pending on the mount, and a mount move waits for the follower's current sub to finish downloading.
- Never two autofocuses at once. The lead and follower autofocus are
serialised through a single mutex — whichever asks first runs; the other waits its turn. Your PC is never loaded with two focus sweeps at the same time.
Setting it up
- Settings → Piggyback — turn piggyback on.
- Settings → Follower train — name it, choose the follower camera / focuser /
filter-wheel transport (ASCOM or Alpaca), and fill in the Capture plan: filter, exposure, binning, an optional cooling target, refocus-every-N-frames, and whether to loop.
- Connect the follower devices — they appear as a tinted Follower group
on the equipment dashboard (amber, or a dim ember under the night-vision theme).
- Run it — either press Start follower on the dashboard's Follower panel,
or arm it (Capture plan → enabled) so it starts automatically when your lead sequence begins and stops when the sequence ends (however it ends).
Files
Follower frames save to their own subfolder (named after the follower train) so they never mix with the lead's.
Notes & current limits
- The follower has no dedicated autofocus settings yet — its refocus sweep reuses
the lead's [autofocus] configuration.
- Cooling sets the follower's target and begins imaging; the camera stabilises
while it runs (a bounded "wait for cooldown" is a later refinement).
- v1 shoots a single looping recipe (one filter/exposure); multi-filter follower
plans are a planned extension.