Telescope

Introduction

IMG_2617 circuit view 0 mirror view 20 axle side 60

IMG_20151026_1731351-e1447598212935 (1)

I designed and fabricated an automated goto, tracking telescope. ‘Goto’ means that the telescope
IMG_20150731_1821291 can rotate and change its position using motors to point to a specified celestial object. ‘Tracking’ means that it can track the apparent motion of the object, caused by the rotation of the earth about its axis. The telescope receives coordinates of the desired celestial object from the user using a smart-phone or a laptop. This telescope can be used to view stars, planets, nebulae and certain galaxies. Its large aperture captures light from distant celestial objects and focuses it at a spot to give a bright image. It is about 1,000 times more powerful than the human eye.

Given the size and complexity of this project, I have broken down the description of this project into pages (modules). Firstly, please watch the description video at the top of this page. It will give a quick overview of the entire project along with short clips of the telescope in action!

Appears reddish due to scattering of light. Image taken with a digital camera (afocal position)

The Rising Moon

Notice the craters near the 'Terminator'. Image taken with a digital camera (Afocal position)

Half Moon

 

 

 

 

 

 

 

Image taken using a webcam (Prime focus). Stacked with Registax

Jupiter (the planet)

Image taken using a webcam (Prime focus). Stacked with Registax

Saturn (planet)

 

 

 

 

 

 

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This telescope comprises of several parts which I have discussed in detail (scroll to the bottom of the page):

Mirror(Optics): I made the primary mirror which is the main optical element in this telescope, at the Inter-University Centre for Astronomy and Astrophysics(IUCAA), Pune.

After getting the desired curvature, the mirror was aluminium-coated by a vacuum metalizing

process. Aluminium is ‘boiled’ to 3000 degrees in a vacuum chamber and the vapors are accelerated and deposited on the surface of glass to create a reflecting mirror.

OTA and Mount: I used the Dobsonian design for the telescope mount and made suitable

modifications to accommodate the motors and gears. I constructed the Optical Tube Assembly
(OTA) using PVC plumbing pipes.

Gears and other components: I designed and fabricated severalIMG_20150731_1822281
custom-components for this project. I required specialised worm-gears with a high gear
ratio(~250:1) which were not available in the market. So I went to Mr Abhay Deshmukh’s machine shop (Logical Automation Solutions) and with his guidance, I made 2 aluminium worm gears for the
vertical and horizontal axis. The other custom made parts include support axles, motor shafts and curved support clamps for the optical tube. These were also made in local machine shops.

Motors: I used high precision, high-torque, stepper motors to control the telescope’s motion in the
vertical and horizontal axis. I built motor driver circuits to control the DC stepper motors by providing appropriate logic signals.

Programming and tracking: The brain of the telescope is an Arduino Uno microcontroller.
I coded a program in C++ for the Arduino to act as a user-interface for the telescope. It receives IMG_20151011_0646591input from the user and controls the telescope’s motion by sending signals to the motor drivers, for tracking the movement of celestial objects in the night sky.

 

Below are links to the pages describing all the components:-

How it works

Unlike popular belief, the main aim of an astronomical telescope is to gather a large amount of light, not magnification. When viewing very faint and distant objects like stars and galaxies, our main concern is the quantity of light reaching our eyes, then comes the size of the object. The telescope has a large aperture […]

Mirror Making

In the summer of 2013, after my 10th high-school exams, I attended a mirror making workshop at IUCAA, Pune where I learnt how to grind a telescopic mirror. I made a 100mm primary mirror for my telescope in this workshop. IUCAA telescope making guide I started with two 100 mm mirror blanks (circular glass discs) […]

Mount and other components

Mount: The design for the mount is a simple Dobsonian. It is easy to construct and the easiest to use. There are main part of a dobsonian mount are: Wooden side supports Bearing/D support for OTA Castors/Ball bearings for azimuth rotation I will let the pictures do the talking as the mount design is pretty […]

Gear Making

There are several types of gears that have their own benefits in various situations. For my telescope, I required a gear system that Would greatly improve the precision of the stepper motor I was using. The telescope can be said to be very precise in positioning, if the least count of the motor’s motion is […]

Motors and electronics

Before starting this project, I had no idea about servo or stepper motors. I required a motor that: Could provide sufficient torque Is either extremely accurate(~0.01 degrees)(no motor is this accurate) or can be attached to a reduction gear to make it really accurate Is not very expensive So I did some research on the internet, […]

Programming and Tracking

Programming: I used an arduino microcontroller as the main processing unit. I wrote a program that acts an interface between the user and the electronics. It receives input from the user through a serial monitor, which can be an application on a laptop, tablet or smart-phone, and gives the output to the motor drivers that […]