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ING Annual Report 1998
Previous: Chapter 3 - Telescope Operation | Up: Table of Contents | Next: Chapter 5 - Public RelationsChapter 4
Telescope Performance
USE OF TELESCOPE TIME
The available observing time on the ING telescopes is allocated between British, Dutch and Spanish time allocation committees, the CCI International Time Programmes (ITP), service and discretionary nights, and scheduled stand-down/ commissioning time.
The PPARC-NWO Joint Steering Committee has delegated the task of time allocation to British and Dutch astronomers to the PPARC Panel for the Allocation of Telescope Time (PATT). On the other hand it is the responsibility of the IAC to allocate the Spanish time via the Comité para la Asignación de Tiempos (CAT). The ratio of UK PATT:CAT:NL PATT:ITP is nominally 60:20:15:5. This ratio is monitored and small differences in these proportions in any one year are corrected over a number of observing seasons.
Service nights listed in the following table belong to UK PATT and NL PATT (ratio 5:1). CAT also provides service time out of their quota. The aim of the ING service programme is to provide astronomers with a way to obtain small sets of observations, which would not justify a whole night or more of telescope time. For each telescope and instrument several nights per month are set aside especially for this purpose. During those nights, ING support astronomers perform observations for several service requests per night.
Discretionary nights are used partly for minor enhancements, calibration and quality control tests, etc., and partly for astronomy, for example, as compensation for breakdowns or for observations of targets of opportunity. They are scheduled together with service nights for greater flexibility, but a careful record of service observations per nationality is kept.
Stand-down and commissioning time is used for basic maintenance, quality control, and upgrades to the telescope and instrument systems.
The way the available observing time on the ING telescopes has been shared in semesters 98A and 98B is summarised in the table above.
Allocation of time for semesters 98A+98B
WHT INT JKT Nights % Nights % Nights % UK PATT
(includes Irish and Portuguese time on the JKT)170.5 46.7 157.0 43.1 201.0 55.1 SP CAT 59.0 16.2 62.0 17.0 59.5 16.3 NL PATT 40.5 11.1 39.0 10.7 50.5 13.8 UK/NL WFS (from 98B on) - - 33.0 9.0 - - ITP 16.0 4.4 16.0 4.4 16.0 4.4 Service/Discretionary 46.0 12.6 29.0 7.9 18.0 4.9 Commissioning 29.0 7.9 26.0 7.1 17.0 4.7 Stand-down 4.0 1.1 3.0 0.8 3.0 0.8 Total 365.0 100.0 365.0 100.0 365.0 100.0 LARGE SCALE IMAGING SURVEYS WITH THE INT WIDE FIELD CAMERA
During the spring of 1997 the Wide Field Camera was commissioned in the prime focus of the INT. This new instrument offers unique opportunities for the UK/NL communities to execute high resolution, deep, wide field optical imaging surveys.
At its meeting in October 1997 the Joint Steering Committee considered ways to stimulate the use of the INT Wide Field Camera for survey programmes. The Committee reflected on the changing role of the INT in the era of the 8-meter class telescopes. It considered the INT ideally suited for programmes of target selection for later follow-up study with large telescopes, and for larger scale survey programmes with a clear scientific goal in their own right. This observing time will be allocated independently from the existing time allocation committees such as PATT, the NL PATT, and the CCI International Time Projects.
The JSC delegated the assessment and peer review of these programmes to the ING Survey Review Panel (ISRP). The ISRP reported to the May 1998 meeting of the JSC and recommended that five weeks of time be devoted to survey programmes in semester 98B and six weeks in semester 99A.
USE OF INSTRUMENTATION
The following tables show for each telescope the number of nights in semesters 98A and 98B for which the different instruments were used. Stand-down (but not commissioning) periods are excluded. The abbreviations are explained in J. The list of common-user instruments for the same period of time can be found in Appendix B.
Again ISIS, as spectrograph or spectropolarimetre, and UES are the most used WHT instruments, but with the improved large CCD detectors available, prime focus imaging and AUTOFIB-2 are becoming very popular. Both AUTOFIB-2 and INTEGRAL are used in combination with WYFFOS spectrograph at GHRIL. When the telescope is in Nasmyth or Cassegrain configuration, imaging at the Auxiliary Port of the Acquisition and Guidance Unit at the Cassegrain focus is also possible. On the INT, dark time periods are becoming almost exclusively used for CCD imaging with the Wide Field Camera. JKT is now a single instrument telescope for CCD imaging.
Use of instrumentation for semesters 98A+98B
William Herschel Telescope ISIS ISIS Pol UES LDSS PF AUTOFIB GHRIL WHIRCAM INTEGRAL TAURUS CIRSI MCCD ELECTRA Total Nights 128.0 21.0 21.5 73.0 36.0 34.5 4.0 25.0 7.0 22.0 4.0 10.0 5.0 361.0 % 36.6 6.0 6.1 20.9 10.3 9.9 1.1 7.1 2.0 6.1 1.1 2.8 1.4 100.0
Isaac Newton Telescope WFC IDS Musicos CIRSI MOMI Total Nights 148.0 142.0 37.0 29.0 6.0 362.0 % 40.9 39.2 10.2 8.0 1.7 100.0
TELESCOPE RELIABILITYTelescope downtime due to technical problems averaged 2.7, 5.2, and 2.3% on the WHT, the INT, and the JKT respectively in 1998 (semesters 98A and 98B). The continuing low figures are particularly creditable in view of the range of new systems, both instruments and infrastructure, that were commissioned during the period, and the substantial reductions in night time technical and astronomy support. [ Technical down time.tiff | Weather down time.tiff | Monthly weather statistics.tiff ]
Percentage of weather and technical down time by semester
Semester WHT
weatherWHT
technicalINT
weatherINT
technicalJKT
weatherJKT
technical89B 42.5 10.5 90A 49.6 8.0 90B 30.9 6.6 13.0 5.0 91A 18.4 12.1 16.9 4.4 91B 28.8 5.5 33.0 5.7 92A 22.8 13.6 23.6 4.9 92B 32.4 9.0 34.8 5.5 93A 20.4 5.2 20.7 4.8 93B 30.5 4.0 27.9 2.7 94A 13.3 3.1 11.8 3.4 16.7 3.5 94B 19.7 3.5 23.7 2.5 24.1 4.3 95A 15.8 2.8 18.1 3.6 14.8 3.1 95B 38.8 3.4 33.8 2.9 33.7 0.9 96A 29.2 3.1 25.5 2.1 37.9 3.5 96B 37.2 1.7 28.9 2.2 34.9 2.3 97A 10.1 3.3 17.6 3.2 20.7 3.7 97B 24.0 3.7 25.2 4.8 26.9 2.9 98A 15.6 2.5 18.6 5.7 19.3 1.6 98B 21.1 2.9 18.5 4.8 21.2 3.0
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