1.For a parabolic telescope that is 100m in diameter, with anaperture efficiency of 1.0, calculate the Gain in K/Jy. Compare your numberwith what you can discover about the gain of the GBT....

Problem1
Gain(or sensitivity ) of a telescope in units of
y
k
J
is given by
A tT AG
S

Where AT =brightness temperature
S=flux density
tA =Average collecting area of the telescope
Where A
e
2kT
S
A

eA = Aperture efficiency
K=Boltzmann Constant

A t e t e tT A A A A AG
S 2k 2761
   

The given data are
2
2
t
D
D 100m A 7853.9 7854m
2
Ae 1 (given)
 
      
 



Substituting the values in the above equation, we get

1e t
y
A A 7854
G 2.84kJ
2761 2761
  

The above obtained gain is the same for GBT telescope, because GBT telescope is having the same diameter of
100m

1
y e(GBT) :Gain(kJ ) 2.84A
 





Problem 2

The beam width ( or Angular resolution) in arc seconds is given by
206244
''
D

 
Where D=diameter of the telescope (m)
= wavelength (m)
the given data are

8
9
frequency 1.4GHz
c 3x10
0.21414m
1.4x10
Diameter D 32m
 
  




Substituting the values in the above equation, we get
o
206244 206244x.21414
'' 22.99arcseconds
D...