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Plots of uncalibrated data

Figure 1: The uncalibrated weights against time for all baselines to Effelsberg in a single channel (VPLOT). The weights written by the correlator are based on the ratio of the amount of data from the tape/disk that contributed to the correlation coefficient for that integration to the amount that theoretically should have contributed. Thus the weights should ideally be close to one as is the case in this plot. If more than one channel is plotted though the weights will be the sum of the weights in each channel. A lot of Onsala data is missing as the telescope could not observe due to high winds.
\includegraphics[scale=0.6]{WEIGHT_UNCAL.PS}

Figure 2: Uncalibrated amplitude and phase as a function of frequency for the single scan on the bright fringe finder OQ208 for all baselines to Effelsberg (POSSM). Several of the sub-bands are dead, for a variety of reasons. The amplitudes have not been calibrated. In general, there is a phase slope across each IF as well as a phase offset between IFs. These are removed to first order with delay calibration (Section 6). Note that the amplitude scale is labelled mJy when in fact it should be correlation coefficient - the amplitudes are uncalibrated!
\includegraphics[scale=0.75]{POSSM_UNCAL.PS}

Figure 3: Uncalibrated amplitude and phase as a function of time for the duration of the experiment. All baselines to Effelsberg are shown. The phase-referenced nature of the experiment is clear in this plot, the amplitudes varying regularly between the phase-reference source and the weak target. A large quantity of the Onsala data is also seen to be useless as the bright phase-reference source cannot be distinguished from the weak target (in phase) after the first four scans. Although the telescope had stopped observing after about 40 minutes, the tape seems to have continued running and these ``data'' have been correlated.
\includegraphics[scale=0.6]{VPLOT_UNCAL.PS}


next up previous contents
Next: 5 Amplitude calibration Up: 4 Data inspection and Previous: Data flagging   Contents
Stefanie Muehle 2008-01-28