---
# System prepended metadata

title: Telescopes Note
tags: [' Science and Life', ' 通識', NTNU, ' Introduction to Astronomy']

---

---
title: Telescopes Note
tags: NTNU, 通識, Science and Life, Introduction to Astronomy
description: '{%hackmd @NTNUCSIE112/Telescopes %}'
---

- Optical Telescopes
    - Telescopes
    
    | Telescopes | Reflecting                                        | Refracting                           |     |
    | ---------- | ------------------------------------------------- | ------------------------------------ | --- |
    | picture    | ![](https://i.imgur.com/kMQoZSG.png)Prime­Focus   | ![](https://i.imgur.com/cEgCwVQ.png) |     |
    |            | ![](https://i.imgur.com/G54esfx.png)Newtonian     |                                      |     |
    |            | ![](https://i.imgur.com/w9LkS79.png)Cassegrain!   |                                      |     |
    |            | ![](https://i.imgur.com/6Cs5g2l.png)Coude/Nasmyth |                                      |     |
    | bad        | But cannot make it  bigger  than 5m in diameter   | Bad chromatic aberration             |     |
    |            | Equatorial mount                                  | Cannot make a big telescope          |     |
    |            | Mirror becomes too heavy and get distorted        |                                      |     |
    | good       |                                                   | Easy to maintain                     |     | 
    - Equatorial mount
        - one rotational axis parallel to the Earth's axis of rotation
        - Evolution：Alt-Azimuth mount 
            - rotate around horizontal and vertical axes 
            - provide angular readouts
    

- Non-optical Telescopes
    - Using entire electromagnetic wave bands
        - Radio Astronomy
            - Interferometr
            - VLBI ( Very Large Baseline Interferometry )
                - EVN ( The European VLBI Network )
                - VLBA ( Very Lager Base Array)
