Difference between revisions of "Basic Interferometry"

From AstroBaki
Jump to navigationJump to search
Line 28: Line 28:
 
%%INSERT PICTURE OF INTERFEROMETER
 
%%INSERT PICTURE OF INTERFEROMETER
  
A two-element interferometer consists of two telescopes seperated by a distance $\mathbf{b}$, called the baseline.  Both antennas receive electromagnetic radiation from an astronomical source in the sky.   
+
A two-element interferometer consists of two telescopes seperated by a vector $\mathbf{\hat{b}}$, called the baseline.  Both antennas receive electromagnetic radiation from an astronomical source in the sky, which is in the direction of the unit vector $\mathbf{\hat{s}}$.  Because astronomical sources are far away, the radiation received by the antennas is in the form of plane waves. As the plane waves reach the antennas,  one will actually receive the signal first and the second will not receive the signal until a certain amount of time has passed.  The time that needs to pass is called the \emph{geometric delay}, and is denoted by the variable $\tau$.
Because astronomical sources are far away, the radiation received by the antennas is in the form of plane waves. As the plane waves reach the antennas,  one will actually receive the signal first and the second will not receive the signal until a certain amount of time has passed.  The
+
 
 +
In order to find the value of $\tau$
  
 
   
 
   

Revision as of 11:54, 12 September 2011

Basic Interferometry

Interferometry is the practice of using a two-or-more-element radio telescope array to observe astronomical sources. The array itself, along with the electronics used to synthesise the signals detected by the telescopes, are what we call the interferometer.

A two-element interferometer consists of two telescopes seperated by a vector , called the baseline. Both antennas receive electromagnetic radiation from an astronomical source in the sky, which is in the direction of the unit vector . Because astronomical sources are far away, the radiation received by the antennas is in the form of plane waves. As the plane waves reach the antennas, one will actually receive the signal first and the second will not receive the signal until a certain amount of time has passed. The time that needs to pass is called the geometric delay, and is denoted by the variable .

In order to find the value of