Overpass 0.3.0

I spent an afternoon with the HAZ46 and the Sun moving the mount between Normal and Special mode, and most of this release is what that turned up about how the mount behaves when it changes mode.

Download

Overpass-0.3.0.dmg below, for macOS 14 or later, signed with my Developer ID and notarised by Apple. Open it and drag Overpass to Applications, replacing 0.2.0.

Normal and Special mode

• Connect by USB in Normal mode as well as Special mode, for Passive and Step tracking over the cable without the mount's WiFi.
• Connected by USB, a button in the mount panel switches between Normal and Special mode without disconnecting. Tracking stops and the mount is held still before the switch, including the sidereal tracking Normal mode can start by itself.
• It turns out the HAZ46 keeps its position through a mode switch, but for a few seconds after leaving Special mode Normal mode reports a placeholder of az 0, alt 0 or az 180°, alt 90°. A sync sent during that window is added to the position the mount kept, which is how I managed to double mine. Overpass now waits for the real position before doing anything.
• After leaving Special mode the hand controller asks for an alignment, and Normal mode will not track until it is synced. Overpass syncs it once the real position is back, on the target if the scope is within half a degree of it, otherwise on where it knows the scope points, and reads the position back to check. If the mount was left that way by a disconnect, it happens on the next Normal mode connect.
• Overpass keeps its own record of where the scope points across launches, holds it when the mount disagrees so a bad reading cannot overwrite a good one, and writes every mode switch and sync to a mount log.

Syncing

• Sync on the target works in both modes. In Special mode it moves Overpass's own alignment zeros and sends nothing to the mount; in Normal mode it syncs the mount and reads the position back.
• Settings has "Set position" for when you know where the scope points, and "Test mode switching", which switches modes with nothing moving and reports what the mount reads at each step.

Tracking

Overpass has three ways to track, and which one you get depends on the mode the mount is in.

• Passive, in Normal mode, is the mount doing the work. Overpass slews to the object the allowed way round the cable stop, sends an RA/Dec goto, sets the mount's own tracking rate (solar for the Sun, lunar for the Moon, sidereal for stars and planets) and then leaves it alone. It re-centres the Moon every five minutes, because the Moon's parallax moves it more than the lunar rate allows for, and for a geostationary satellite it slews there and holds. It is the right choice for anything that moves steadily across the sky, and the wrong one for a satellite crossing it.
• Step, in Normal mode, is Overpass sending a goto to where the target will be every few seconds. Fine for an antenna, jumpy in a telescope.
• Smooth, in Special mode over USB, is Overpass varying both axis speeds continuously. This is the one for satellites.

Changes this release:

• Passive tracking stays active while the mount tracks, watching the mount's own status and saying so if it stops. Before this it handed over to the mount and looked finished, which on the Sun was enough to convince me it had stopped. Overpass sends no motion commands in that time, only a status check every few seconds.
• How often Normal mode is polled and the shortest Step interval are a setting, from 0.5 to 5 s with 1 s as the default, since sub-second commands in Normal mode have given me trouble.

Sky view

Drag on the dome, or twist on a trackpad, to spin it to the way you are facing. It snaps to N, E, S and W, and the buttons in the corner flip east and west and put north back at the top.

Not yet tested on hardware

The automatic sync after switching to Normal mode, Passive tracking's status watching, and crossing north under rate control during a slew. Every quirk measured so far is in docs/iOptron-Special-Mode-Protocol.md under "HAZ46 quirks, measured", which is worth reading before trusting any of it on an HAE.