Several projects in radioastronomy plan to use large static cylindrical
reflectors with an extended lobe sampling a sector of the rotating sky. This
study provides the exact mathematical expression of the transit time of a
celestial object within the acceptance lobe of such a cylindrical device. The
mathematical approach, based on the stereographic projection, allows one to
study the optimisation of the position and orientation of the radio-reflector,
and should provide exact coefficients for the spatial Fourier Transform of the
radio signal along the cylinder axis.Comment: 15 pages, 13 figure