Westerbork Synthesis Radio Telescope (WSRT)

The Westerbork Synthesis Radio Telescope (WSRT) began operation in 1970 as the most sensitive distributed array for imaging astronomical sources at radio frequencies. Now, some 33 years later, it has essentially regained that role with an instantaneous continuum-sensitivity equivalent to that of the Very Large Array (VLA) in the United States. This is the result of a comprehensive upgrade of the facility that was completed in 2002. The 14 fully-steerable parabolic reflectors, distributed in an East-West configuration of 2700 m length, that make up the system have been given a complete mechanical overhaul. A state-of-the-art receiver package has been placed in the prime focus of each antenna, which provides almost continuous coverage from 250 MHz through 8700 MHz. Any of the eight discrete feed systems that together provide this total frequency coverage can be rotated into the 14 antenna foci in under a minute, providing a very high degree of frequency agility. A new intermediate frequency (IF) system allows 160 MHz of bandwidth in two perpendicular polarizations to be brought back to the control building for further processing. The digitised signals of the array can either be coherently added, for VLBI or pulsar observing applications or cross-correlated, for local imaging applications with great flexibility. For example, local imaging of continuum radio sources typically utilizes the full 160 MHz of spectral bandwidth, sampled in spectral channels of 310 kHz width and all four cross-polarization products, while observations directed at particular spectral lines may utilize a spectral resolution as high as 300 Hz. Essentially any desired combination of spectral bandwidth, resolution, number of polarization products and number of correlated antenna can be provided by the half million complex channels of the new WSRT correlator system.

All of the data acquired with the WSRT is stored in a permanent data archive, from which it is exported to the proposing users. Users enjoy proprietary data rights for a period of one year, during which publication of results is normally expected. After the proprietary period, archival data is available on request to the general user community. Highly trained support staff (made up of PhD astronomers currently active in research) has been employed by the WSRT observatory to provide assistance to prospective users in the preparation of observing proposals and subsequently to assist in the calibration and imaging of their WSRT data, either via correspondence or during a data-reduction visit. Data-reduction visits of WSRT users are supported by providing local accommodation, office space, workstations, and access to general infrastructure and the technical assistance of the WSRT scientific support staff.

The WSRT TNA contact is R. Vermeulen
rvermeulen@astron.nl

More information can be found on the WSRT Homepage.