A study of four open clusters on Tautenburg Schmidt plates in the direction to the Galactic Centre (I = 17.0', b = $0.8') is presented. In a field of 8.95 square degrees proper motions and B , V magnitudes were determined for about 36 500 stars up to the limiting magnitudes B = 17m9, V = 16?8. For stars brighter than B = 16m an accuracy of about 3 maslyear has been estimated for proper motions. The rms errors of stellar magnitudes and (B -V) colours is about 0.1 mag.
There are two open clusters already known in this sky area: Trumpler 32 (C 1814-133) and NGC 6611 (C 1816-138). By the inspection of the plates two additional anonymous clusters were identified near the double star ADS 11285 or BD -14'5014 (C 1819-146) and near the star BD -14'5016 (C 1820-146). The cluster membership determination was carried out using information on spatial and proper motion distributions of stars in the field. The colour-magnitude diagrams up to the limiting stellar magnitude were constructed. For each cluster interstellar extinction A v , diameters of the core and corona, ages and spatial velocity components (V, W) relative to the LSR in the Y, Z-galactic directions were derived. The distances to the clusters were obtained to 1720 pc, 2 260 pc, 2 130 pc and 2 130 pc for Thmpler 32, NGC 6611, C 1819-146 and C 1820-146, respectively. All clusters are situated in the Sagittarius-Carina spiral arm. Their spatial location confirms the assumption that galactic spiral arms are close to logarithmic spirals with a characteristic angle of about 20 degrees. k e y words: proper motionsopen clusters -HR diagramgalactic centre