Sky finder

Point your phone at the light

Your camera shows the view from the platform with the skyline, the roads in view, lit towers and bright stars drawn on top. After you calibrate on a known light, the crosshair gives a bearing and height good to a fraction of a degree. That is far better than a phone compass alone.

How to use it

  1. Start at the Viewing Area. Tap Start and allow the camera and motion sensors. Stand away from the car and metal railings, which throw off the compass.
  2. Calibrate on something you can identify. Put the crosshair on a known light, such as a red tower light or a bright star or planet, and tap Calibrate. Choose one close to where you'll be looking. The phone's compass error changes with direction.
  3. Aim and record. Put the crosshair on the light you want to measure and tap Record. The 1×/3×/8× button magnifies the picture and the drawing together, for precise aiming. Hold still for a second. The measurement goes into your field log, and the report form can import it.
  4. Check, and check again. Every few minutes, put the crosshair back on your calibration light and tap Check. The difference is your real measurement error, and it is saved with your readings.

At night the camera picture is mostly black. That's normal. The drawn skyline, roads and stars are what you aim with. At dusk you can line the drawn skyline up with the real one using the zoom slider.

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Not calibrated

Calibrate

Put the crosshair exactly on one of these, hold still, then tap it. Pick one near the direction you'll be measuring.

Recorded

Make a report from it →

Settings

Adjust until the drawn skyline matches the real one at dusk. This sets the camera's field of view. It affects the drawing only, not your measurements.