Harvard University Astronomy Lab and Clay Telescope

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Measure Elevation and Azimuth of Jupiter and Aldebaran

This lab should serve as an introduction to the night sky. Positions of celestial objects on the sky are measured with two angles: i) azimuth, or the horizontal (in the plane of the ground) angle of the direction to an object vs. the direction to the North, and measured East of North; and ii) elevation, the angle between the object on the sky and the horizon directly below. Celestial positions are changing with time and so three measurements must be made: azimuth, elevation (azimuth and elevation are both in degrees) and time (date and time, to the nearest 30 seconds).

Azimuth angle is the number of degrees from True North. Azimuth angles can then range from 0 degrees (North), to 90 degrees (East), to 180 degrees (South), to 270 degrees (West) and then back to 360 degrees (North). Elevation, also referred to as altitude, angles will range from 0 degrees (on the horizon) to 90 degrees (on the zenith).

What you need:

• a red flashlight
• paper and pencil
• clock
• sextant

Procedure:

• You should first visually locate Aldebaran and Jupiter in the night sky. Jupiter will be the brightest object overhead and Aldebaran is the bright star in Taurus. Use the star chart (chart 1) to help guide you.
• We will use the sighting tube sextant (your TF will show you the proper use) to find Jupiter and record the Elevation angle.
• Next, you will want to slowly lower the sextant vertically downward from your object toward the horizon while sighting along the tube and find a landmark. Then, we'll use our iPhones (or equivalent), in "Compass" mode, to "measure" the actual "absolute" Azimuth of the landmark.
• We will then repeat this process for Aldebaran, recording the Elevation angle and then the Azimuth angle.