l'Histoire se répète:
Just like Jan Oort had been thinking about the design and realisation of the Dwingeloo radio telescope while important astronomical observations were being made with the Kootwijk antenna, so did he conceive the next major step while the Dwingeloo telescope was producing results.
On his instigation Charles Seeger wrote a conceptual proposal for a large cross-shaped radio telescope. In the fall of 1958 this proposal was discussed for the first time in the board of the Netherlands Foundation for Radio Astronomy.
The proposal was a conceptual one, aiming for a telescope with a resolution of 1 arcminute or better. No definite proposal of operating wavelength was made, but Seeger used 75 cm as a reasonable possibility. This would imply that the arms of the cross would have to be approximately 3 km long. A large number of rather simple antenna systems above a reflecting screen were proposed as receiving elements. In order to have a reasonable operating speed, this system could be made to operate with 50 or more simultaneous beams in a raster of, for instance, ten in declination by five in hour angle.
It was clear that realisation of an ambitious project like a large Cross- antenna would exceed the possibilities of a small country like The Netherlands. Therefore, Oort and Bannier, the director of Z.W.O. (Netherlands Organisation for the Advancement of Pure Research) had contacted Dr. P. Bourgeois of the Uccle Observatory and representatives of the Belgian Department of Education to discuss collaboration between Belgium, the Netherlands and possibly Luxemburg for development of the design of a new large radio telescope.
A fifty-fifty collaboration between Belgium and the Netherlands was proposed and, in principle, accepted. As no funds on the Belgian budget were allocated for this purpose, it was suggested to submit the project to the Office for Scientific and Technical Personnel of the O.E.E.C. (Organisation European Economic Cooperation) for support of the project. Although this constituted a considerable delay the suggestion was accepted.
A draft letter of agreement was prepared and discussed in September 1959; the agreement with the O.E.E.C. was signed in June 1960. The international project started initially under the name `Benelux Radio Telescope' but was soon renamed the `Benelux Cross Antenna Project' (BCAP). Belgium and the Netherlands were equally represented in the council of the project. Oort was its president and Dr. Coutrez the secretary-treasurer.
The council had 17 meetings in the years 1960 to 1965 (3 in 1960, 4 in 1961, 3 in 1962, 4 in 1963, 2 in 1964 and one in 1965) An 18th meeting was planned for early 1967 but was never held. The budget of the project, which at that time included only the cost of preparation and design, increased gradually from NLG 100,000 in 1960 to 680,000 in 1964. Eight members of staff were working on the project in 1961. In 1964 this number had increased to eighteen. Some members of the staff were entirely or partly paid by other institutions than the BCAP.
During the first two years substantial financial support was obtained from the O.E.E.C., which was transformed in 1961 into the OECD. (Organisation for Economic Co-operation and Development). As a result of the international complications technical and scientific personnel were not employed until the middle of 1960, but some of the people already working in Leiden and Dwingeloo started generating ideas. Of decisive importance was Dr. W.N. Christiansen joining the project in November 1960. Christiansen had had prior experience in the field of building antenna arrays. Dr. J.A. Högbom, who came to Leiden at approximately the same time after earning his Ph.D. in radio astronomy in Cambridge, was also going to have great influence on the project.
In December 1961 the OECD sponsored an international meeting on `Large Radio-Telescopes' in Paris, which was attended by virtually all international experts in the field, by seventeen members of BCAP staff and astronomers from Belgium and the Netherlands, and by official government delegates from at least ten countries. The proceedings of that meeting (1961) contain descriptions of large telescopes in existence as well as planned, but also discussions of astronomical programmes which would become possible with the planned large telescopes like the Benelux Cross Antenna (cf. Oort's Dream, this volume, and Oort,1961) At that meeting two different designs for the Benelux telescope were discussed by Högbom (1961). As we'll see in the following section these were the first stages of development towards the telescope that would be built ultimately.