ESO data flow system in operations: closing the data loop

On 1 April 1999, the first unit telescope (ANTU) of the ESO VLT began science operations. Two new instruments (FORS-1 for optical imaging and spectroscopy and ISAAC for IR imaging and spectroscopy) were offered in a mix of 50% visitor mode and 50% service mode. A Phase-I and Phase-II proposal and observation preparation process was conducted from 1 October 1998 until the middle of March 1999 involving approximately 280 proposals. A total of 1768 Observation Blocks for 83 approved service mode programs were scheduled and executed between 1 April and 1 October 1999. The resultant raw science and calibration data were subjected to quality control in Garching and released to the ESO user community starting from 15 June 1999 along with pipeline processed data products for a subset of instrument modes. The data flow loop for the first LT telescope is closed. The current operational VLT data flow system and the developments for the remainder of the VLT will be presented in the light of the first year of operational experience.