Detection, excision and statistics of interference at the Mauritius Radio Telescope

A technique to detect man-made interference in the visibility data of the M auritius Radio Telescope (MRT) has been developed. This technique is based on the understanding that the interference is generally 'spiky' in nature a nd has Fourier components beyond the maximum frequency which can arise from the radio sky and can therefore be identified. We take the sum of magnitud es of visibilities on all the baselines measured at a given time to improve detectability. This is then high-pass filtered to get a time series from w hich the contribution of the sky is removed. Interference is detected in th e high-pass data using an iterative scheme. In each iteration, interference with amplitudes beyond a certain threshold is detected. These points are t hen removed from the original time series and the resulting data are high-p ass filtered and the process repeated. We have also studied the statistics of the strength, numbers, time of occurrence and duration of the interferen ce at the MRT. The statistics indicate that most often the interference exc ision can be carried out while post-integrating the visibilities by giving a zero weight to the interference points.