The Lembang's Photographic Observations on Sirius

The photographic observations on the components of Sirius were made at the Bosscha Observatory (1955-1986) after the invention of the Sirius grating by van Albada (1956). This special grating enables us to photograph the two components that differ by 10 magnitudes. An overview on the technique of the photographic observations on this pair is presented in this paper, as well as the method of measurements and reductions. Combination of our results with the measurements carried out at the US Naval Observatory (1965-1972) on this pair have covered almost all the observable part of a revolution. An orbit determined by van den Bos (1960), which based mostly on visual observations, fails to agree with photographic measurements. It gives negative residuals in the position angles and large discrepancies in the separations. Revision to the orbit is, therefore, necessary to carry out.