Apple Watch

StarHop Navigator includes a small companion app for the Apple Watch. It shows you live where to move your telescope and lets you log observations directly from your wrist — without taking the iPhone out of its mount on the telescope tube.

What the watch shows

The watch interface is deliberately minimal. It displays:

the name of the currently selected target (e.g. “M31”) at the top, across the full width of the screen,
a large direction arrow in the center, indicating which direction to move the telescope — N / NE / E / SE / S / SW / W / NW. The arrow snaps between these eight fixed directions instead of moving smoothly. This is intentional: it is a hint, not a real-time tracker (see the note below),
two small values stacked at the bottom-left: Az +0.5° and Alt −0.6° — the signed deviations in azimuth (left/right) and altitude (up/down). These are what you actually steer by when moving the telescope on two axes,
a green check-mark symbol at the bottom-right — the log button.

Once you reach the on-target zone (angular distance below approximately 0.5°), the center arrow is replaced by a green check mark. The Az/Alt values remain visible.

If no target is selected on the iPhone, the watch shows “No target selected”. If the watch cannot currently reach the iPhone (app in background, iPhone off, out of range), a small “iPhone not reachable” indicator appears at the bottom-left in place of the Az/Alt values.

Why does the arrow snap and only update twice per second?
The watch receives pointing data from the iPhone over Bluetooth, and this transmission has an inherent latency of 200–300 milliseconds — no app can change this. If we animated the arrow smoothly with every incoming update, it would look like a real-time tracker but drag noticeably behind — and you would inevitably “overshoot” when trying to follow it.
So we chose a deliberately honest display: a coarse arrow that snaps twice per second. At a glance you see which direction to adjust, and you read the precise remaining deviation as a number — no attempt to fake smooth tracking that the platform cannot deliver.

On-target haptic

Once the angular distance drops below approximately 0.5° — that is, when the target becomes visible in the eyepiece — the watch emits a short tap, and the green check mark replaces the direction arrow in the center. The tap is purely haptic — no speaker sound. It fires once per approach: if you swing past the target and return, you feel the next tap. As long as you stay on target, the watch stays quiet.

Note on strength: The tap is intentionally subtle. watchOS doesn’t offer a way to produce a strong vibration tap that is also completely silent (that would require CoreHaptics, which Apple doesn’t ship for watchOS). We’ve chosen silent and subtle — during night-time observation, sound disturbs more than a discreet tap.
If the tap feels too weak, check on the watch under Settings → Sounds & Haptics → Haptic Strength whether it is set to “Prominent” (instead of “Default”) — that’s the only system-wide amplifier. The primary feedback signals for “target reached” are the green check mark on the watch and the angular distance value on the iPhone.

The 0.5° threshold is tuned to typical telescope setups (see docs/notes/fov-accuracy-explained.md in the repo). In this first version it isn’t configurable in the settings — let us know if it triggers too early or too late for your setup.

Logging from your wrist

When you have a non-star target aligned, you can press the green check-mark symbol at the bottom-right of the watch. The iPhone then creates an observation entry with all the standard data (location, equipment, session, weather — exactly as the green confirmation button on the iPhone’s main screen would).

The watch emits a short, purely haptic tap and shows a banner confirmation at the top of the screen for about one second (green on success, red on failure). No speaker sound — the banner color is the primary feedback; the tap is just an additional confirmation.

Stars — calibration instead of logging. When a star is selected as the target, the log button on the watch triggers star calibration on the iPhone — exactly as the green confirmation button on the iPhone does. In this case no observation entry is created; instead the sensor calibration is extended by this measurement. The watch reports back the same way with check-mark haptic and a brief banner.

Note: If the target changes between tapping “Log” and the iPhone receiving the message, the iPhone replies with “Target has changed” and nothing happens.

What the watch cannot do

The watch is an extension of the iPhone, not a standalone app. The following is not available on the watch:

Selecting or changing targets — you do this on the iPhone (catalog, favorites, constellations).
Standalone calibration interface — selecting the star and managing the calibration list happens on the iPhone. The log button on the watch only adds a measurement to a star that has already been selected.
Catalog, equipment or settings screens — everything on the iPhone.
Its own sensors — the watch does not use its own compass or accelerometer. All pointing data comes from the iPhone, which is mounted on the telescope and calibrated.
Complications / Always-On / background operation — the watch app must be in the foreground, and the iPhone app must also be running. If the watch goes to sleep and you raise your wrist again, the app automatically retrieves the current target state from the iPhone.

Requirements

iPhone with StarHop Navigator (iOS 17 or later), in the foreground and launched.
Apple Watch (watchOS 10 or later), paired with the iPhone.
StarHop Navigator on the watch in the foreground — either via the app launcher or installed from the Watch app on the iPhone (it ships together with the iPhone app).

Status indicator on the iPhone

As soon as an Apple Watch is paired with your iPhone, a small Apple Watch symbol appears on the main screen at the top-left — at the same height as the calibration indicator on the right. The symbol is deliberately plain: no status dot, no colored ring. Just its presence means “a watch has been detected”. If no watch is paired, the symbol isn’t shown at all.

Tapping the symbol opens a small status overview with exactly one of three messages:

Connected — the watch app is installed and currently exchanging data with the iPhone.
Watch waiting for iPhone — the watch app is installed, but the live link is not currently active (e.g. because the watch is in the background or just woke up).
Watch app not installed — an Apple Watch is paired, but the StarHop companion app has not been installed on it yet. In this case — and only then — an additional button “Open Watch app” appears, which takes you directly to the Apple Watch app on the iPhone, from where you can install the companion with a single tap.

The sheet deliberately doesn’t explain what the watch app does — that’s what this manual is for. It is a pure status display and affects neither target selection nor calibration nor the ongoing data transfer to the watch.