deletions | additions       diff --git a/subsection_Faint_Images_of_the__.tex b/subsection_Faint_Images_of_the__.tex  index ac70b70..a97a1d0 100644  --- a/subsection_Faint_Images_of_the__.tex  +++ b/subsection_Faint_Images_of_the__.tex 
...
\subsubsection{Trade-off between area and depth in FIRST survey}  The radio band is approximately five decades in wavelength - tens of meters to millimeters. This is too wide to be covered effectively by a single telescope \& / receiver. The specific intensity and angular sizes of radio sources span an even wider range than the radio band a combination of single telescopes \& /receivers andaperture-synthesis  interferometers are therefore required to for effective detection. who simultaneously achieve a high angular resolution, large field-of-view while keeping in practical design limitations.  The basic interferometer is a pair of radio telescopes whose voltage output are correlated (multiplied and averaged).The averaged). The  larger the collecting area of an ideal radio telescope, telescope - for a given system temperature,  the more it can detect faint radio sources. The sensitivity of the collecting telescope  area is given by σ=(2k_B T_sys)/(A_e 〖(Δν_RF τ)〗^(1/2) ) $\sigma = \frac{2k_{B} T_{sys}}{A_{e} \times ( {(\Deltaν_{RF} \times \tau)}^{\frac{1}{2}}) }$  where T_sys the temperature of the interferometer system, Δν_RF is the receiver radio-frequency bandwidth, τ is the duration of the signal received from the interferometers.