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Instruments and Resources for Astronomy Enthusiasts and Professionals

Wndsn is interested in stargazing -- primarily with the naked eye -- and the revival and making available of ancient techniques, measuring, and calculating instruments. (More information.)

Here you will find an overview of our (custom-tailored upon request) instruments as well as freely available guides and books that are commercially available. Also check out our popular online calculators (see below) for the sun and stars.


Various astronomical quadrants by Wndsn.

Astronomical Quadrants by Wndsn for different degrees of latitude with various auxiliary scales.

The Wndsn Moon Clock

The universal moon clock by Wndsn in deep red light.

Astronomical Quadrant

The Wndsn Astronomical Quadrant is a high quality measurement instrument for navigation and the determination of distances and altitudes. It is based on the principle of the Horary Quadrant, an ancient astronomical device that measures and calculates time based on the position of the sun or some other celestial body. In addition, the Astronomical Quadrant allows the determination of the position of the sun as well as light and shadow calculations over the course of a year at the calculated degree of latitude.

However, the Astronomical Quadrant is more than just a clock: it allows the user to determine their latitude, among other things. It can also be used as a Telemeter to measure the distance or height of an object by measuring the angle between the object and the observer.

On the front side are degree and inclinometer arcs, as well as scales for calculating sine, cosine, and tangent for a given angle. In addition, scales for equal and unequal hours, the latter dependent on latitude, and a calendar with markings for equinoxes and solstices.

A number of navigational stars can be added to the Astronomical Quadrant, allowing quick reference and calculations of right ascension, hour angle, as well as cardinal direction and time of night.

On the back there is a range finder with a built-in calculator for determining angle sizes.

All the necessary calculations, trigonometry, and mathematics, are directly accessible via a string that serves both as an index and as a measuring aid.

Crafted from acrylic or brass, the Astronomical Quadrant features a series of scales and tables that allow for quick and accurate calculations. It is fully configurable to the individual needs of the user: it can be provided with different scales and prepared for a specific degree of latitude. The Astronomical Quadrant is a unique and versatile tool for adventurers, explorers, and enthusiasts of applied science.

Moon Clock

The universal Moon Clock is a simple equatorium to determine compass direction, and average approximate time (in unequal hours) by observing the phases of the moon. The front is intended for use in the northern hemisphere, the rear (mirrored) view for use in the southern hemisphere.

The universal moon clock is a teaching and experimental instrument to demonstrate ideal conditions for the equinoxes and their derivations and extrapolations over the course of the year.

Why are Telemeters and Quadrants of Interest to Astronomers?

Telemeters and Quadrants are not only practical tools for observing and navigating the sky, but also fascinating learning and visualization tools that bring the history of astronomy and geodesy to life.

Wndsn's Telemeters and Quadrants combine a thousand years of civil engineering, surveying, navigation, and astronomy and are based on historical models such as the astrolabe, the Sine Quadrant or the Shadow Square. They show how our ancestors measured and understood the sky without modern technologies.

Applications of Wndsn Instruments in Astronomy

  • Determining the angle of the Earth's magnetic field in relation to the horizontal plane
  • Measuring the height of the sun to determine the time of day
  • Calculating the declination for a given day
  • Setup and use of the Quadrant Telemeter as an equatorial sundial
  • Calculating various data from the altitude and declination of the sun, such as hour angles, daylight hours, compass direction of the sun, etc.
  • Reading and calculating right ascension and hour angle of celestial objects
  • Reading and calculating culmination times of celestial objects
  • Calculating duration and start and end times of twilights
  • Calculation of distances with the nomograph from angular sizes, which are determined e.g. with devices with a reticle
  • Determining the angular size of a body considering dimensions and distance

Online Tutorials


Wndsn Quadrant Telemeters: Official Manual (GQT5).

Wndsn Quadrant Telemeters: Official Manual (GQT5).

The Sine Quadrant

The Sine Quadrant (Excerpt from GQT5).

Wndsn Quadrant Telemeters: Official Manual (GQT5)

  • Description and use of the Wndsn Quadrant Telemeter. The manual describes the techniques for using the instrument's functions and includes the basic concepts and advanced instructions, formulas, and reference tables. The 5th Edition of the Official Guide to the Mastery of Time and Space describes and teaches the operating system of the Quadrant Telemeter, and once more expands the knowledge of the Wndsn suite of telemetry tools. The book is a textbook for both the beginner and the expert with a completely new section demonstrating standard situations for applied trigonometry in the field with various ways of sighting and processing the acquired data with detailed examples.

The Sine Quadrant

  • This book is an excerpt from the comprehensive GQT5, and contains the description of the Sine Quadrant, its features, principles, functions, and methods, together with an introduction to the astronomy required. It describes instructions for all basic functions as well as advanced methods and graphically elaborated formulas. The chapters on the functions of the Sine Quadrant have been completely revised and expanded based on the results of new research, with full explanations demonstrating its completeness as a "supercomputer" for solving any trigonometric problem.

The books are available as hardcover, paperback, and Kindle editions.


To complement our instruments and to provide educational materials and multiple ways of accessing our equipment and techniques, we provide a range of calculators to accompany our digital and printed textbooks, as practice aids, to obtain a 'third opinion' and to demonstrate underlying principles.

Sun Calculator

  • Measure local latitude and use our Solar Calculator to determine declination for a given date, to calculate a number of latitudinal, diurnal, and/or instantaneous solar values.

Star Calculator

  • Determine culmination, azimuth, and hour angle based on a star's declination and altitude with our Star Calculator.


Contact us at any time if you are interested or have any suggestions or inquiries at:

  • info [at] wndsn [dot] com

Happy stargazing!

Wndsn Astronomy Store