1 - WHT OPERATIONS DURING 2018A ------------------------------- 0.7% of the observing time was lost to technical problems. This is well below the target level of 5%. The lengthy TCS-replacement standdown (see Section 3) meant that fewer nights were available for observing than during most past semesters. The numbers of nights allocated to each common-user instrument in 2018A were approximately: ISIS 24; LIRIS 12; ACAM 11. (Where an observer requested two instruments, e.g. LIRIS + ACAM, the credit has been split between the two.) ISIS remains our most-popular common-user instrument, and ISIS+LIRIS have a 48% share of all nights, and 77% of nights allocated to common-user instruments. The WHT hosted 1 visiting instrument this semester: PAUCam. 9 user feedbacks were received for runs during 2018A. All rated the run 'good' or 'excellent'. 2 - TIME-LOSS STATISTICS FOR 2018A ---------------------------------- 11 technical faults, 7 hours lost, mean 0.6 hours per fault. The faults arise in a broad range of sub-systems. No fault caused more than 3 hours to be lost. NB these statistics (as in previous reports) refer to *all* nights, including S/D/commissioning, and nights when visitor instruments were used. 3 - ACTUAL USE OF S/D/STANDDOWN IN 2018A ---------------------------------------- Service Observed 10.0 Bad weather 1.4 Technical problems 0.0 D/comm Tel. quality control 3.9 Instr. quality control 0.5 TCS standdown 64.0 (for replacement of TCS) WEAVE standdown 11.0 (to measure flexure at top end) Aluminising 0.0 Bad weather 11.1 Technical problems 0.0 ----- 101.9 Total S = 11.4 = 10.0 + 1.4 associated bad weather + technical problems. Total D = 90.5 = 79.4 + 11.1 associated bad weather + technical problems. 4 - WEATHER AND TECHNICAL DOWNTIME IN 2018A ------------------------------------------- The last three columns below give for each month the numbers of observing hours lost to bad weather and to technical problems, and the number of nights considered when compiling these statisics (= all those which were not S/D/commissioning or own-instrument). Mon Yr weath tech nights hrs hrs 2 18 190 0 23 3 18 19 0 7 4 18 0 3 4 5 18 0 0 0 6 18 0 0 1 7 18 0 0 10 Chris Benn 2 October 2018