1 - WHT OPERATIONS DURING 00B ----------------------------- Time lost to technical problems was 2.2%, similar to the average for the last 5 years, and well below the target level of 5%. NAOMI was commissioned on 11 nights in August and September 2000, by a large team from Durham/ATC/ING. Most of the commissioning goals were achieved, despite losing much of the time in August to rapid telescope oscillations up to +- 0.5 arcsec which NAOMI could not correct for (now almost eliminated by tuning the telescope-drive feedback loop). Diffraction-limited images FWHM ~ 0.12 arcsec were obtained in K band, and similar resolution was achieved in J and H bands. Most of the remaining commissioning work will be carried out off-sky, with NAOMI in the test focal station, during Mar - May 2001. One major concern is the high level of the K background at the INGRID detector when used with NAOMI (3 mags higher than at Cassegrain), and this is under investigation. The on-sky time in May and Jun 2001 will be used principally for characterising performance as a function of wavelength, natural seeing, guide-star magnitude and radius from guide star. In particular, the wavefront sensor's faint-star mode will be commissioned, giving an extra mag in guide-star limit (and ~ a factor of 3 in sky coverage). NAOMI's performance in the optical must also be characterised, to make sure it meets the requirements of the coronograph (~ spring 2002) and OASIS (~ spring 2003). It should be possible to start this work in May/Jun 2001, but a further 4 nights will be required in 2001B to characterise the in-slit energy as a function of seeing, guide-star magnitude and radius from the guide star (including self-referenced galaxy nuclei) for at least two wavelengths. The estimate of 4 nights (8 half nights) is based on past experience characterising the performance of NAOMI in the IR. TEIFU, the integral-field fibre feed to WYFFOS, will be the only spectroscopic facility available with NAOMI until the commissioning of OASIS at the end of 2002, and 2 nights are requested to commission it with NAOMI in 2001B. 3 night are required in 2001B for tests of the Rayliegh laser beacon (which will provide moderate AO correction over a wide-angle field), in particular to characterise off-axis performance as a function of wavelength, beacon height and vertical turbulence distribution. In order to sample a range of turbulence conditions, 6 half nights spread over a 10-day period are required. Individual allocations of less than 0.5 night are not useful. The new aspheric for INGRID's foreoptics was installed in Feb 2001. At the same time, the pupil imager was repaired (allowing faster, more accurate alignment), and new narrow-band filters and new stops (for the future AO coronograph) were installed. In addition, a new cold-cycle cooler head was installed to increase cooling capacity. This will eventually allow INGRID to be run at Cass without frequent topping up of liquid N2 (although INGRID with NAOMI will continue to be run with liquid nitrogen, to minimise vibrations). INGRID's on-sky performance will be re-characterised in March 2001. The small-fibre module for AF2 (1.6-arcsec fibres instead of the current 2.7 arcsec) will be commissioned in July 2001. Use of smaller fibres will reduce the sky background. Use of continuous fibres from AF2 to WYFFOS is also expected to increase throughput, by up to 1 magnitude. All fibres have now been polished, and the prisms and buttons glued on and aligned. The microlenses are currently in the UK being coated. The science fibres will be integrated into the module in April. Once the small-fibre module has been commissioned, the large-fibre module will be withdrawn. Plans for the WYFFOS long camera, permitting change of detector at an external focus (e.g. allowing possible use of an IR detector), have been revived, and detailed design work is under way. Spectral resolution up to 9500 will be available with small fibres and echelle mode. The new design would permit imaging of up to 1000 fibres. ESA/ESTEC's innovative superconducting-tunnel-junction camera SCAM/STJ had a fourth run at the WHT in September 2000. Discussions are under way between ING and the ESA group about future use of this technology to provide the detector for a fibre-fed wide-field spectrograph with sufficient spectral resolution e.g. for obtaining photometric redshifts. It may also provide a future facility for very fast photometry. 1 night is required in 2001B to commission the University of Sheffield's ULTRACAM, a high-speed, triple-beam imaging camera allowing msec exposures. The new San Diego controller (SDSU) and ULTRADAS data-acquisition system has now been commissioned with all WHT CCDs except the aux-port TEK (to be converted May 2001). Beyond 8000 A, the QE of the CCDs currently in use falls off rapidly with increasing wavelength, and some of the CCDs (particularly the 2k * 4k EEVs) suffer from serious fringing. MIT offers CCDs with nearly doubled QE in the far red, and very little fringing. ING has a share in a foundry run of these CCDs, with the aim of building two new cameras. Delivery is expected in 2001 (a test device has already been delivered). Half a night in 2001B is required to commission these, mainly to test the fringing level. A new CCD-based camera was purchased to begin replacement of the obsolete Westinghouse acquisition TV cameras on the WHT and INT. Such cameras should permit acquisition of objects as faint as V = 24. The shutter of the camera proved unreliable and it been redesigned by the supplier. A replacement is expected shortly. The primary mirror was aluminised in June 2000, and the reflectivity in January 2001 was still 87%. Under the new cleaning regime, no time is required for aluminising in 2001B. NAOMI and associated instrumentation currently have to compete with INTEGRAL and visiting instruments (e.g. SCAM) for time on the GHRIL Nasmyth platform. Moving NAOMI in and out of GHRIL is time-consuming and risky (even though it has its own optical bench). Over the next couple of years, the AO instrumentation may be moved to the other Nasmyth platform, with UES moving to a fibre-fed location outside the telescope. These plans do not affect operations in 2001B. All but 3 of the 12 user feedbacks for 00B rated the WHT's performance 'good' or 'excellent'. Three rated performance 'sufficient', two of these due to the problems with INGRID/TCS and with high readout noise from ultradas noted below. The other included miscellaneous complaints about admin support, telescope performance and user manuals. None of the feedbacks rated performance 'poor'. The few negative comments have no common themes except that two feedbacks described the Residencia computing facility as being 'useless'. 2 - TIME-LOSS STATISTICS FOR 00B -------------------------------- 46 faults, 38 hours lost, mean 50 minutes per fault, similar to previous semesters. Faults which caused more than 3 hours to be lost on a given night: - 5 hours lost Oct 2000 to failures of AF2 fibre setup, due to corruption of a data file transferred by the observer using ftp in binary mode instead of text mode. The AF2 software will be modified to trap this when the WHT instrument-control software is moved to unix (~ 2002). - 5 hours lost Jan 2001 to an oil-pump failure. - 3 hours lost Nov 2000 to failure of communication between INGRID and the telescope-control system, due to mounting of the wrong disk after a reboot (which in turn was due to the disk name not being changed when ultradas was implemented). In addition, two observing runs were compromised by the high readout noise on CCDs used in binned mode, after conversion to ultradas Jan 2001. One night of scheduled observing reverted to service when an observer didn't arrive on time. 3 - STANDDOWN AND D-NIGHT BID FOR 2001B --------------------------------------- (This is what is in Rene's draft bid to ING board INGB(01)09 19/3/01) Standdown (commissioning work): NAOMI performance in optical 4 (8 half nights) OSCA 1.5 (3 half nights) Rayliegh laser tests 3 (6 half nights, Aug) TEIFU 2 (Sep?) ULTRACAM 1 (Oct - Dec) Red-sensitive CCDs 0.5 -- 12 D-nights: Telescope quality control 2 (optical tests, pointing tests) Instrument quality control 2 Instrument setups after changes 2 (including 0.2 nights dark time) -- 6 -- Total 2001B commissioning + D 18 The nights bid for are all bright, apart from the 0.2 nights required for setup of the PF imaging camera (usually ~ 2 dark hours at the start of a 'grey' night). 4 - STANDDOWN AND D-NIGHTS USED IN 00B -------------------------------------- 17.5 nights used for standdown (13.8) and discretionary (3.7) work and associated 4.1 nights bad weather and technical problems (see table below). I.e. the totals, including bad weather and technical problems, are 17.0 nights standdown, 4.6 discretionary = 21.6 in all. 5 - ACTUAL USE OF S/D/STANDDOWN IN 00B -------------------------------------- Service 14.9 Tel. quality control 2.8 (mostly investigations of tel. oscillations) Instr. quality control 0.9 Commissioning 13.8 (see below) Aluminising 0.0 Bad weather 6.7 Technical problems 0.9 ---- 40.0 (= 21.6 in (4) above + 14.9 service + 3.5 bad weather and technical problems associated with service) The 13.8 nights used for commissioning/standdown include 10.9 for NAOMI, 1.4 for laser-guide-star trials, 1.0 for installation of the He pipes in the Cass wrap, 0.5 for SCAM. 6 - WEATHER AND TECHNICAL DOWNTIME in 00B ----------------------------------------- The last two columns below give for each month the % of observing hours lost to bad weather and technical problems respectively. S/D, commissioning and own-instrument nights are excluded from these statistics. Mon Yr weat tech % % 8 00 0.0 1.6 9 00 7.2 0.0 10 00 28.2 2.5 11 00 11.2 4.1 12 00 29.0 0.7 1 01 9.5 3.4 --- Mean 2.2 (weighted by number of nights each month which satisfy the above criterion) In terms of time lost to bad weather, the winter 2000/01 has been the mildest since WHT records began in 1990. Chris Benn 2001 Feb 26, version 2001 Mar 16