The major device at the NAO is the 2-meter Ritchey-Chretien-Coude telescope with a modern light detector – a CCD camera. This is the largest telescope in Southeast Europe. It is used to observe different types of stars, star clusters, nebulas, galaxies, planets, asteroids, and comets. Because of the universal optic system of the telescope, besides photometric observations for obtaining direct images, spectral observations can be made for studying the chemical composition of objects. On the basis of such observations, some important findings have been reported: The research of MWC560 has led to the identification of a new class of symbiotic double systems. The globular star clusters research project has led to a better understanding of their morphology and dynamic characteristics. On November 24, 1985 the first European photograph of Halley’s comet was made at the Rozhen NAO. For several years active photometric observations of comets are being made with a focal reducer, one of the new additions to the telescope, in order to learn more about their astrophysical characteristics.