Name: Partner(s): Day/Time: Version: detroit

# Coordinate Systems and Telescopes at the Detroit Observatory

You must complete one of the planetarium or the celestial sphere parts before doing this activity.

### Preliminary question:

How would you tell what system (equitorial or alt-az) a telescope is set up to use? (hint: both systems have a fixed axis, either az or RA. Figure out what the orientation (horizontal, verticle, at some specific angel...) of this axis is.)

### Part 1: The 12" Fitz refractor

1. What system (equatorial or alt-az) is this telescope set up to use? How can you tell?

2. What direction does the axis point? Give as a cardinal direction, such as SW.

3. If this telescope were moved to the southern hemisphere, what direction would the axis point? Explain.

4. Why is there a giant weight below the telescope (hint: think about how the telescope will move over the course of a night)?

5. There is a clock drive on one axis to rotate the telescope. Which direction does it rotate: clockwise or counter-clockwise as viewed from the eyepiece end? Is this the same direction as the Earth? Explain.

6. How can you tell this is a refractor without being told?

7. What does the 12" mean?

### Part 2: the Meridian 'Scope

This telescope mount is mounted to use one coordinate system, but to measure the positions of objects in the other system. Note the shutters open up to give a view of the meridian.

1. What system (equatorial or alt-az) is this telescope set up to use? How can you tell?

2. This telescope only moves on one axis. Which axis? Why is that desirable? (hint, what is a meridian telescope used for?)

3. What direction does the axis point?

4. This telescope can be used to find your latitude very precisely. How?

5. This telescope can be used to measure the sidereal time. How?