The blocking of one antenna's beam by another in a synthesis imaging array. Shadowing occurs especially when observing at low elevation angles. Shadowing results in a decrease in the amplitude of correlations since the shadowed antenna has an asymmetric primary beam. This also results in an effective change in the interferometer spacing. Shadowed antennas are automatically flagged by the AIPS task FILLM assuming a 25 m aperture, but can be changed by the user. Large correlated signals can occur near shadowing. Correction of shadowed data has been partially successful at Westerbork.
References
VLA Scientific Memorandum No. 134.
