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Wndsn Quadrant Telemeter Tutorials

Making the most out of our graphical telemetry computers.

Like with many complex instruments, there are multiple ways to solve certain problems and to measure the required inputs. Combining the various functions leads to a multitude of advanced uses.

Measuring Star Time

Level: Advanced

With our Telemeter, we can measure angular size not just of fixed objects, but also of moving objects over time. An application derived from this is to determine time passed by observing fixed stars and measuring them against static objects on earth.

Measuring time against the stars.

Measuring time against the stars.


The earth completes one full rotation of 360° in 24 hours, and thus -- 360/24 -- turns 15° in one hour, and 7.5° in 30 minutes, 5° in 20 minutes, or 1° in 4 minutes.

By using the Telemeter to compare the position of a fixed star to the apparent lateral distance to a fixed structure on earth, provided we observe from the same vantage point, it becomes possible to measure the difference in degrees over time and with the knowledge above, passed time.

What we need

  • A Telemeter (any model that measures degrees)
  • A fixed object, such as a building
  • A starry night and an easily recognizable star, e.g. Sirius, Betelgeuse, etc.

The method

  1. Use the Telemeter horizontally with the string held taut and align the 0-degree mark with the edge of the building.
  2. Measure the initial distance from the edge of the building to the star.
  3. After some time, measure the distance to the star again.
  4. Convert degrees to minutes.


  1. We are tracking Sirius with a starting measurement of 2° apparent distance from the building next to it.
  2. For the second measurement, Sirius is at 6.5° for a distance of 4.5°.
  3. Recalling that 1° ≙ 4 minutes, we calculate that 18 minutes have passed.


Newer Telemeters (as of 2020) have an additional mark at 7.5°, to measure up to 30 minutes of elapsed time. Of course, the method works with any Telemeter using smaller increments or the techniques of extending the scales.

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