SRT- Small Radio TelescopeFor more information email:
info-srt@haystack.mit.edu
back to Back to Haystack
Home
Tutorial/Activity

Learning to use the Small Radio Telescope (SRT)

Objective:  Students will learn the basic functions of the SRT interface, and some basic terms of radio astronomy.

The small radio telescope comes with a software controller written in the JAVA computer language. This tutorial is to help you get started with the software and the telescope.  Start up the program in either the simulation mode or the normal (telescope controlling) mode.

1.       A map of the sky.

Standing on the earth’s surface, you can see approximately half of the sky.  The other half you could see if the earth was not there!  Maybe you can see less than half, if your view is obstructed by trees or buildings.  On your screen is a map of the sky.



The numbers on the axes are the coordinates of points in the sky in the reference frame of your telescope.  Azimuth, on the x-axis, tells you the direction on a compass in degrees relative to north.  Elevation, on the y-axis is the angle of the object above the horizon.  Your computer already knows the location of some objects in the sky. 

 

2.   Moving the telescope to point at an object.

           

To point the telescope at one of the objects, click on the object on the map.  Then click “track” at the top of the screen.  The telescope will move to point at the object. 

3.       Moving the telescope to point at any point in the sky. 

You can send the azimuth and elevation of any point in the sky directly to the SRT.  To do this, click on the “azel” button at the top of the screen.  Then click in the text field at the bottom left of the screen.  Type the azimuth in degrees, followed by a space, followed by the elevation in degrees.  Then hit enter.  The telescope should begin to move.


4.       Making a frequency plot for a source.

A radio source is an object in the sky that emits radio waves.  One thing we are interested in is the frequency of the radio waves that these sources emit.   Click the “freq” button at the top of the screen.  Then type in the text box:  “1420.4 51”.  This tells the telescope to take readings in 51 bins centered at 1420.4 MHz.  The default width of a bin is 0.04 MHz.  When you point the telescope at a source or point in the sky, the frequency vs. temperature (intensity) plot will be displayed in the upper right portion of the screen.  The plot on the right is updated each time the intensity is measured at each frequency, while the plot on the left is a time average of all the measurements.

5.       Doing a “25 point plot” of the sun. 

We can see if the telescope is pointing in the correct direction by making a 25 point scan of the sun.  Choose the sun as the source and point the telescope there.  Click “freq” and type “1419 1”.  You want only one frequency.   Click “npoint”, and wait.  The telescope should now scan the area around the sun.  When the telescope is finsihed, it will make a plot of the sun in a small window next to the frequency plot window.  If the sun is centered on the plot, the telescope is pointing correctly.  If it is not, you can enter corrections using the “offset” button.  Click the offset button and enter azimuth <space> elevation of the correction in the text box.

           


Updated: 10 August 1999