Changeset 546
- Timestamp:
- 03/09/05 13:13:32 (20 years ago)
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trunk/doc/cookbook.tex
r544 r546 1144 1144 \subsection{Simple Calibration} 1145 1145 1146 {\em Currently the receiver position angle is not stored in the rpfits 1147 file. This serverly hampers correct handling of polarimetry.} 1146 {\em Currently the receiver position angle is not stored in the RPFITS 1147 file. This severely hampers correct handling of polarimetry. In the future 1148 we aim to define a general framework and populate the RPFITS files 1149 with the data required for transparent polarimetric calibration.} 1148 1150 1149 1151 It is possible that there is a phase offset between polarisation which 1150 will effect the phase of the cross polarisation correlation, and so 1151 give rise to spurious polarisation. \cmd{rotate\_xyphase} can be used 1152 to correct for this error. The user must know how to determine the 1153 size of the phase offset themselves.1154 1155 \begin{verbatim} 1156 ASAP> scans.rotate_xyphase(10.5) 1152 will effect the phase of the cross polarisation correlation, and so give 1153 rise to spurious polarisation. \cmd{rotate\_xyphase} can be used to 1154 correct for this error. At this point, the user must know how to 1155 determine the size of the phase offset themselves. 1156 1157 \begin{verbatim} 1158 ASAP> scans.rotate_xyphase(10.5) # Degrees 1157 1159 \end{verbatim} 1158 1160 1159 1161 Note that if this function is run twice, the sum of the two values is 1160 applied .1161 1162 A correction for the receiver paral actic angle may need to be made,1163 either because of how it is mounted or if paral actifiying had to track1162 applied because it is done in-situ. 1163 1164 A correction for the receiver parallactic angle may need to be made, 1165 either because of how it is mounted or if parallactifiying had to track 1164 1166 at 90 degrees rather than 0. Use \cmd{rotate\_linpolphase} to correct 1165 1167 the position angle. Running this function twice results in the sum of 1166 the corrections being applied .1167 1168 \begin{verbatim} 1169 ASAP> scans.rotate_linpolphase(-20) # Correct for receiver mounting1168 the corrections being applied because it is applied in-situ. 1169 1170 \begin{verbatim} 1171 ASAP> scans.rotate_linpolphase(-20) # Degrees; correct for receiver mounting 1170 1172 1171 1173 # Receiver was tracking 90 degrees rather than 0 … … 1176 1178 \label{sec:polplot} 1177 1179 1178 To plot stokes values, the plotter \cmd{set\_cursor} function should1180 To plot Stokes values, the plotter \cmd{set\_cursor} function should 1179 1181 be called first using the \cmd{pol} argument. The values which can be 1180 plotted include a selection of [I,Q,U,V], [I, Plinear, Pangle, V] or1182 plotted include a selection of [I,Q,U,V], [I, Plinear, Pangle, V], or 1181 1183 [XX, YY, Real(XY), Imaginary(XY)]. (Plinear and Pangle are the 1182 1184 percentage and position angle of linear polarisation). Conversion to
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