1 - WHT OPERATIONS DURING 07A ----------------------------- Only 1.9% of the observing time was lost to technical problems, much less than the target level of 5%. The numbers of nights allocated to each common-user instrument in 07A were approximately: ISIS 66; LIRIS 41; AF2 15; prime-focus imaging 12; aux-port imaging 0; OASIS 0; INGRID 0. The Rayleigh laser guide star, GLAS, and the associated control systems, had very successful commissioning runs in June, August and September 2007. Most of the basic technical commissioning is complete, and a start has been made on characterising the near-IR on-sky performance. In H band, correction to fwhm 0.2 arcsec has been achieved, and natural guide stars as faint as R = 18 have been used. Further on-sky characterisation is required before offering GLAS to observers. The MASS turbulence profiler, mounted with the DIMM outside the WHT building, is now regularly delivering estimates of the distribution of turbulence with altitude (essential for interpreting the GLAS commissioning results), although the measurements are not yet fully automatic. In the data obtained so far, low-altitude layers usually dominate, implying that GLAS will deliver useful correction on most good-seeing nights. An L3 (low-light-level) frame-transfer CCD has now been made available to observers for fast spectroscopy on either arm of ISIS. In fast mode, the readout noise is close to zero, and exposures shorter than 1 sec are possible with very small readout overheads. Spectro-polarimetry mode is being offered with LIRIS for the first time in 08A, on a shared-risks basis. The conceptual design review for ACAM (the new instrument which will replace the current aux-port imager) was completed in February 2007. ACAM will offer high-quality broad-band and narrow-band imaging over an 8-arcmin field of view (cf 2 arcmin for the current camera), and probably low-resolution spectroscopy as well. The optical design is approaching completion, with the final design review expected late 2007. A high-QE, low-fringing 2k*4k E2V CCD (similar to the excellent RED+ on the ISIS red arm) has been purchased and will be tested on the current aux-port camera this autumn. Work continues on replacement of the ageing 4MS (forth) instrument controllers by PLC systems. This work is now complete for the prime-focus imager, with successful on-sky commissioning in October 2007. The maximum time required to move the filter wheel from one position to another has been reduced from 50 sec to 5 sec. The conversion of the SDSU CCD controllers from generation 2 to 3 is now complete. The WHT continues to be a popular platform for visiting instruments, with GHaFaS (a new Fabry-Perot imager), INTEGRAL, PNS and SAURON visiting in 07A. The very-high-resolution fibre-fed spectrograph HARPS-N (a Harvard planet-finder, complementing the Kepler mission) is likely to come to the WHT in late 2008. It will be mounted at a (hirtherto-unused) broken-Cass focus, fed by the current Nasmyth flat. A memorandum of understanding with Harvard University is due to be signed late 2007. The WHT's millionth exposure was obtained in August 2007, not long after the 20th anniversary of WHT first light (June 1987). The millionth exposure is a 1-sec image from a series of exposures of a transiting exoplanet. 25 user feedbacks were received for runs during 07A. All 25 rated their runs 'good' or 'excellent'. 2 - TIME-LOSS STATISTICS FOR 07A -------------------------------- 28 technical faults, 26 hours lost, mean 0.9 hours per fault. The faults arise in a broad range of sub-systems. The following problems caused more than 3 hours to be lost: - 8 hours lost Jun 12 to failure of azimuth incremental encoder. Encoder replaced (first time in 20 years). - 4 hours lost Mar 8 due to ISIS grating accidentally being positioned to centre the second order spectrum, rather than first order, on the detector. The instrument-control software has been modified to warn the user if it is asked to calculate grating position assuming any order other than first. 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 07A -------------------------------------- Service Observed 20.0 Bad weather 3.0 Technical problems 0.5 D/comm Tel. quality control 0.5 Instr. quality control 4.3 Commissioning / s'down 9.7 (0.7 for AO TT, 9.0 for GLAS) Aluminising 0.0 Bad weather 2.2 Technical problems 0.3 ---- 40.5 Total S = 23.5 = 20.0 + 3.5 associated bad weather + technical problems. Total D = 17.0 = 14.5 + 2.5 associated bad weather + technical problems. 4 - WEATHER AND TECHNICAL DOWNTIME in 07A ----------------------------------------- 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 07 24 3 15 3 07 87 0 26 4 07 0 0 0 (no nights in April met the above criteria) 5 07 40 3 25 6 07 12 10 23 7 07 1 1 18 Chris Benn 2007 Sep 15