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

- Optical Telescopes
- Telescopes

| Telescopes | Reflecting | Refracting | |
| ---------- | ------------------------------------------------- | ------------------------------------ | --- |
| picture | Prime­Focus |  | |
| | Newtonian | | |
| | Cassegrain! | | |
| | 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)