On May 21, 2011 the open day was held (from 12:00 to 20:00). It was devoted to 190 anniversary of NAO. On this day, the observatory was attended by 800 guests and residents of Nikolaev city. The program consisted of exploring the Observatory an astronomical tour through the museum. Museum includes over 150 exhibits: Ancient astronomical instruments, a collection of astronomical clocks, old books, photographs, paintings and maps. Demonstration of current and historical instruments and thematic lectures on astronomy were conducted. Everyone could see how modern astronomical observations are carried out using fast robotic telescope, multi-channel telescope, mobile telescope, the axial meridian circle, which is a national property of Ukraine.