deletions | additions       diff --git a/subsection_Faint_Images_of_the__.tex b/subsection_Faint_Images_of_the__.tex  index f517f11..cb38a14 100644  --- a/subsection_Faint_Images_of_the__.tex  +++ b/subsection_Faint_Images_of_the__.tex 
...
where $T_{sys}$ is the temperature of the interferometer system, $\Deltaν_{RF}$ is the receiver radio-frequency bandwidth, $\tau$ is the duration of the signal received from the interferometers.   The collecting area of circular parabolic radio telescopes is reduced to an effective area because the receiver is on the reflector axis, and together with its supporting legs, the receiver partially blocks the path of radiation falling onto the reflector. The angular resolution of a diffraction-limited telescope is given by $\theta \approx \frac{\lamba}{D}$ \frac{\lambda}{D}$  radians (where D is the diameter of the radio telescope dish and $\lambda$ is the wavelength of light). Large diameters are required to obtain sub-arc second resolution at radio wavelengths. For example, for 1 arcsecond resolution at 16 Hz need 50 km diameter.  The geometric area of a single dish is(πD^2)/4, while the geometric area of an interferometer with N dishes – (with the basic one as shown in figure 2), given by(NπD^2)/4, can be arbitrarily large. Note that an interferometer can comprise of two or more dishes. This arrangement mitigates many complications associated with single dishes, for example, vulnerability to fluctuations in atmospheric emission and receiver gain, and radio-frequency interference.  FIRST’s high angular resolution and faint flux density threshold (the rms is 0.15 mJy) come at a price. Some of the flux from extended sources is resolved out. This leads to a systematic underestimation of extended source flux density and a survey threshold that is a function of source size  Moreover ,the higher angular resolution achieved by a more extended antenna configuration comes at a price of lower brightness temperature sensitivity. Brightness temperature is a measure of the source brightness (or specific intensity - referring to frequency) irrespective of the radiation mechanism.  FIRST’s high angular resolution and faint flux density threshold (the flux density limit of FIRST is ~ 1 mJ) come at a price. Some of the flux from extended sources is resolved out. This leads to a systematic underestimation of extended source flux density and a survey threshold that is a function of source size specific intensity: $I_{v} = \frac{dE}{dAd \Omega dt dv}$ W.$m^{-2}$.$sr^{-1}$.$Hz^{-1}$  \subsubsection{FIRST and synchrotron radiation - this section is incomplete}