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Unformatted text preview: AST 3722C - Spring 2008 Lab #3: Some Basic Observing. Due before class on March 18. Instructions: This lab asks you to sketch what you see through a telescope, make some simple angular measurements, and derive some physical quantities about the things you observe. Your should probably read through the entire lab once before starting it. Some of this lab must be completed tonight, but the rest can be done at any time afterward. Basically, you should get the “data” tonight and record enough info about what you see so that you can go back at a later date and understand what you did. • Part A. Magnification and Field of View. Each LX90 telescope comes with several eyepieces. When you put an eyepiece into the holder, the objects you see through the telescope are magnified. You will probably notice quickly that the higher the magnification, the smaller the field-of-view (FOV). Also recall that the physically largest eyepieces had the lowest magnification and the largest FOV. The relevant formula for magnification M is: M = f O f E , where f O is the focal length of the telescope, and f E is the focal length of the eyepiece. The FOV, call it θ , when you look through the telescope with that eyepiece depends on the optics of the eyepiece, naturally. The formula is: θ = θ M , where θ is related to an effective focal ratio of the eyepiece’s optics. For all but one of the eyepieces, θ = 52 ◦ = 0 . 91 rad. For the largest eyepiece, θ = 44 ◦ = . 77 rad. This info comes from the manufacturer’s specs. ◦ 1. On each eyepiece case, f E in millimeters is written on the side. Write down the focal lengths f E for all the eyepieces in the LX90 case....
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- Spring '09
- Astronomy, Eyepiece, Angular diameter, too-high power eyepiece