A series of 54 plates photographed in 46 nights was collected with the 60-cm Zeiss double refractor in the years 1976-1986. Plates with multiple exposures were taken using OG I or OG 530 filter and II G or 103aG emulsion. Trails were obtained to determine the direction of the zero-point of the position angle.
A special "Sirius grating" designed by van Albada (1956) was placed in front of the objective lens. The distance between the wires is adjustable so as to make the distances of the first diffraction images from Sirius A equal to the distance A-B. By this arrangement the correction for contraction of the emulsion near the heavily overexposed zeroth order image of the primary can be derived.
The following grating constants w/s were employed (w indicates the number of wires used in the grating, while s denotes the standard spacing in mm): 6/11 (plates 5602-7201), 5/11 (plates 7322-7401), 5/12 (plates 7781-8178), and 5/17 for plates 8410-8449. A hexagonal aperture was utilized to take plates 8039-8449.
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