SUMER observations of the quiet Sun: Transition region and low corona Original Research Article

SUMER — the Solar Ultraviolet Measurements of Emitted Radiation instrument on the Solar and Heliospheric Observatory (SOHO) of ESA and NASA — observed its first light on January 24, 1996 and covered the minimum of the sunspot activty between the solar cycles 22 and 23 with nearly continuous observations. Consequently, in many studies particular emphasis was put on quiet Sun investigations. We will review in this presentation some of the observational results on the transition region and the low corona obtained by UV and EUV emission line measurements. The chromospheric network, including its small scale activity, will be discussed, as well as polar coronal holes.