Telescope lab-FA2020-1020L
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Astr. 1020L Telescope Lab - Questions and Answers
rev.5/15 Name Cameron Rutherford Date ____Sep. 14
th
2023_______ Describe in some detail the questions below, in your own words, using complete sentences.
Clearly labeled sketches of apparatus (use the reverse side) can often greatly help with your explanations. Use additional paper if necessary.
1. How does the alt-azimuth
mount differ from the
equatorial
mount? What are the advantages of each?
Alt-azimuth mounts have two axes of rotation, allowing telescopes to move up and down (altitude) and left and right (azimuth). These are a bit easier to use without having a larger amount of experience, Aswell as being less expensive than the equatorial mount.
Equatorial mounts have two axes aligned with the celestial poles, allowing telescopes to follow the precise motion of celestial objects as Earth rotates. Because of this these mounts are typically the more advanced mount to use when looking to get more accurate detail-oriented information. Although these are harder to set up and more expensive overall.
2. Why must the polar axis
of an equatorial telescope be directed towards Polaris? Will this axis be directed towards Polaris 5,000 years from now? Why or why not?
Because we need a reference point that everything can be centered around to ensure we have a proper celestial alignment. And the best point to do this would be Polaris or the southern hemisphere’s celestial pole. Polaris is easy because it is extremely close to the Northern’s celestial pole even though it is not right on it. And no in 5000 years the axis will not be directed towards Polaris. Earth's axial precession causes the location of the celestial pole to change slowly over time.
This shift is due to the gradual wobbling of Earth's axis caused by gravitational interactions with the Sun and the Moon.
3. Describe the main features of the Schmidt-Cassegrain
telescope used in this lab. Where are the primary and secondary mirrors of our S-C telescopes located, and what are their shapes? What is the diameter of the primary? Hint: One picture is worth a thousand words.
The primary mirror is a concave mirror that is located at the back of the telescope tube. The secondary mirror is a smaller, convex hyperbolic mirror located near the front of the telescope tube. Some of the features are the folded light path and Cassegrain Focus. And I believe the diameter of the primary lens is 280mm.
4. Why do they put telescopes on high mountains or in space?
Generally, the atmosphere is thinner and often has less turbulence and light pollution. The seeing conditions compared to on ground level is just overall better and in space we have access to specific wavelengths that are not accessible on earth because of the atmosphere.
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5. What is the largest refractor telescope? What is the largest reflector telescope?
The largest refractor telescope is the Yerkes Observatory Telescope with a lens diameter of 40 inches.
The largest reflector telescope is the Great Canary Telescope with a primary mirror diameter of 409 inches
6. Most beginner, reflecting, telescopes are 6 or 8 inches in optical diameter. Which one has the greatest
light gathering power? By how much? Hint: Area of a circle=Pi * Radius^2
A 6-inch telescope has a radius of 3 inches, so its light gathering power is π * (3^2) = 28.27 square inches.
An 8-inch telescope has a radius of 4 inches, so its light gathering power is π * (4^2) = 50.27 square
inches.
Therefore, the 8-inch telescope has a greater light gathering power by approximately 50.27 / 28.27 = 1.78 times.
7. What are the features of a “finder ‘scope”
? The features consist of 3 main components that help the scope find and position celestial bodies these features are Low Magnification, Typically provides a wide field of view to make it easier to locate objects. It also usually has some form of Crosshairs or Reticle to help center objects within the field of view. Aswell as an Adjustable Alignment which allows for precise alignment with the main telescope.
8. A telescope has a focal length of 1440 mm. What is the magnification with a 40 mm eyepiece?
What is the magnification with a 10 mm eyepiece? Which eyepiece provides the largest field of view?
With a 40 mm eyepiece: Magnification = 1440 mm (telescope focal length) / 40 mm (eyepiece focal length) = 36x.
With a 10 mm eyepiece: Magnification = 1440 mm / 10 mm = 144x.
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The 10 mm eyepiece provides the largest magnification, but the 40 mm eyepiece provides a wider field of view.
9. Give a good explanation of the purpose of the setting circles
found on our telescopes, and describe how they could be used on our upcoming Deep Sky night at Harrison Bay State Park. Setting circles on telescopes are used to find and track specific celestial objects by specifying their celestial coordinates (right ascension and declination). During the Deep Sky night we can use them
to set the telescope's position to match the coordinates of deep-sky objects in the sky, making it easier to locate and observe these objects.
10. Why is tracking on an altitude azimuth mounted telescope impossible without computers.
Tracking celestial objects with altitude-azimuth mounts can be challenging without computers because these mounts don't naturally follow the apparent rotation of the stars. As a result, the observer must manually adjust both altitude and azimuth axes to keep the object in view.
11. Name 3 items of Star Party etiquette.
Dim lighting, Respecting Observers, and No white lights.
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