Rozhen Observatory (Bulgarian: Национална астрономическа обсерватория "Рожен", НАО-Рожен - NAO-Rozhen) is a Bulgarian astronomical observatory, located 90 km south of the city of Plovdiv, Bulgaria. The nearest town, Chepelare, is 15 km away. It is owned and operated by the Institute of Astronomy of the Bulgarian Academy of Sciences. The Observatory is the largest in Southeastern Europe and has an active team of about 50 astronomers. It is the principal center for astronomical research in Bulgaria.
- 200 cm Ritchey-Chretien telescope (supplied with Coude focus)
- 60 cm Cassegrain telescope
- 50/70 cm Schmidt camera
- 15 cm Solar telescope
WASP-3c & TTV
Transit Timing Variation (TTV), a variation on the transit method, was used to discover an exoplanet WASP-3c by Rozhen Observatory, Jena Observatory, and Toruń Centre for Astronomy.