Technical losses from VLT Visitor Mode observations have been analysed over four Periods (P95 – P98) and are reported here in response to a request from the Users Committee. The technical losses in Visitor Mode, and for global Service Mode and Visitor Mode in parenthesis are as follows on the VLT: UT1: 2.2% (3.4%), UT2: 2.5% (3.1%), UT3: 3.4% (4.6%), UT4: 1.2% (3.9%); on VLTI: 3.8% (7.9%).
VM Technical Losses
Visitor Mode technical loss fractions are lower than global technical loss fractions, mainly due to proactive re-scheduling of observing runs in case of known technical problem with the requested instrument, and also because, in case of technical failures, recovery priority is generally given to instruments in Visitor Mode. While the time lost to a Visitor Mode run is not usually reimbursed, compensation may be granted by the Observatory Director in cases where over 2/3 of the programme has been lost due to technical failures (see the Information for Visiting Astronomers).