%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% function [az, el] = applyDiurnalAberration(az, el) name is pretty self-explanatory %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0001 function [az, el] = applyDiurnalAberration(az, el) 0002 0003 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 0004 % 0005 % function [az, el] = applyDiurnalAberration(az, el) 0006 % 0007 % 0008 % name is pretty self-explanatory 0009 % 0010 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 0011 0012 0013 tiny = 1e-7; 0014 0015 theta = acos(cos(el).*sin(az)); 0016 0017 % If the source is along the direction of the tangential velocity 0018 % vector then the azimuth and elevation are unaffected. 0019 if(abs(theta)<tiny) 0020 return; 0021 end 0022 0023 x = -cos(el).*cos(az); 0024 if(x~=0 | sin(el) ~= 0) 0025 psi = atan2(x, sin(el)); 0026 else 0027 psi = 0; 0028 end 0029 0030 % The aberration causes the source to appear to shift towards 0031 % the direction of the site's velocity. Since the tangential 0032 % velocity of the Earth is directed along the y axis, this 0033 % results in a reduction of theta. 0034 0035 theta -= actual_.velocity/cvel.*sin(theta); 0036 0037 % Compute the modified azimuth and elevation. 0038 el = asin(sin(theta).*cos(psi)); 0039 0040 % Compute the new azimuth, unless pointing at the zenith. The 0041 % azimuth is irrelevant at the zenith. 0042 if(cos(theta) ~= 0 | (sin(theta).*sin(psi))~= 0) 0043 az = atan2(cos(theta), -sin(theta).*sin(psi)); 0044 else 0045 az = 0; 0046 end 0047 0048 return; 0049