Mauritius Radio Telescope

The Mauritius Radio Telescope (MRT) is a synthesis radio telescope that is used to make images of the sky at a frequency of 151.5 MHz. The MRT was primarily designed to make a survey with a point source sensitivity of 150 mJy. Its resolution is about 4 arc min. The MRT is a T-shaped array consisting of 1019 fixed helical antennas in the East-West arm (2 km) arranged in 32 groups and 64 helical antennas, four per trolley, on 16 movable trolleys in the North-South (880 m). There is a single trolley in the North arm. The North South arm is built along the old Port Louis to Flacq railway line.

The antennas collect radio waves and transform them into electric signals. The signal from each group is filtered, amplified and sent to the telescope building where it is digitized. The digitized signals are processed in a correlator. Custom written software running on GNU/Linux OS computers is used to transform these correlated signals into raw images called dirty maps.

The MRT uses the technique of aperture synthesis to simulate a 1 km by 1 km filled array. Observations are made with the trolleys in the South arm at their nearest position from the array centre. The trolleys are then moved further south and the observations repeated 62 times. This process continues until the end of the south arm is reached. The 1-D data for each day is added so as to make a 2-D map of the sky. Unlike most radio telescopes, the MRT can 'see' very extended sources. Also, the non-co-planarity of the East-West arm have led to new imaging techniques used in cleaning the raw data.

Although the MRT was primarily designed to conduct the 151.5 MHz survey, it has also been used for pulsar observations. During pulsar observations, only the East-West arm is used. The group outputs are added together, with a tracking capability of about 2 degrees for a source transiting at meridian. This corresponds to 8 minutes for an equatorial source. The data is recorded at a fast rate over a band width of 1 MHz. The data processing is done to produce a dedispersed output in the desired format, including the pulsar profile unique to each pulsar.

The MRT is also meant to map our galaxy, the Milky Way. A point source catalogue of around 100,000 objects is to be produced. Already 3 observation rounds of the southern sky have been made. In addition, solar data has also been collected. About 300 GB of raw data has been collected.

References

Golap, K.; Udaya Shankar, N.; Sachdev, S.; Dodson, R.; Sastry, Ch. V.; J. Astrophys. Astron., 19, 35-53 (1998) ADS scanned article

The Mauritius Radio Telescope brochure by G. K. Beeharry.

External links

• Mauritius Radio Telescope (MRT)