Jan Walery Jedrzejewicz (1835-1887) And His Observations Of Comets

Jan Walery Jedrzejewicz was a medical doctor with active practice in Plonsk and an astronomer by passion. In fact, astronomy was a second profession for 'Dr. Jedrzejewicz', as he signed his astronomical publications. He built his own observatory in Plonsk, small village situated about 70 km from Warsaw, which he equipped with professional instruments. Thanks to that, he could perform precise astronomical observations. In the astronomical community, he was known and esteemed for his precise measurements of double stars. He also measured the position of many comets discovered at that times, including long-period ones. This study is devoted to the analysis of precision of Jedrzejewicz measurements on the examples of three long-period comets, today known as C/1885 X1 Fabry, C/1885 X2 Barnard and C/1886 T1 Barnard-Hartwig.