Slide 21
Slide 21 text
T(l,m)
• V(u,v), the complex visibility function, is the 2D Fourier transform of T(l,m), the
sky brightness distribution (for incoherent source, small field of view, far field, etc.)
[for derivation from van Cittert-Zernike theorem, see TMS Ch. 14]
!
• mathematically
u,v are E-W, N-S spatial frequencies [wavelengths]"
l,m are E-W, N-S angles in the tangent plane [radians]"
(recall )
T(l,m)
van Cittert-Zernike theorem, see TMS Ch. 14]
al frequencies [wavelengths]"
s in the tangent plane [radians]"
)
19
Interferometry basics
visibility
sky brightness
Visibility and Sky Brightness
• V(u,v), the complex visibility function, is the 2D Fourier trans
sky brightness distribution (for incoherent source, small field
[for derivation from van Cittert-Zernike theorem, see T
!
• mathematically
u,v are E-W, N-S spatial frequencies [wavelengths]"
l,m are E-W, N-S angles in the tangent plane [radians]"
(recall )
Visibility and Sky
• V(u,v), the complex visibility fun
sky brightness distribution (for i
[for derivation from van Citt
!
• mathematically
u,v are E-W, N-S spatial freque
l,m are E-W, N-S angles in the
(recall )
Interferometer observes 2D components u,v of Fourier
transform of sky brightness