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ING Annual Report 1997
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 nights.
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 with 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 97A and 97B is summarised in the table above.
Allocation of time for semesters 97A+97B WHT INT JKT Nights % Nights % Nights % UK PATT 162 44.4 169 46.3 189 51.8 CAT 60 16.4 63 17.3 65 17.8 NL PATT 42 11.5 43 11.8 51 14.0 ITP 16 4.4 16 4.4 16 4.4 Service 26 7.1 21 5.7 10 2.7 Discretionary 22 6.0 10 2.7 11 3.0 Stand-down/
commissioning37 10.2 43 11.8 23 6.3 Total 365 100.0 365 100.0 365 100.0 USE OF INSTRUMENTATION
The following tables show for each telescope the number of nights in semesters 97A and 97B for which the different instruments were used. Stand-down (but not commissioning) periods are excluded. The abbreviations are explained in Appendix B and J.
ISIS comprises three modes of operation: ISIS, ISIS+Aux, and ISIS+fibers. In semesters 97A and 97B GHRIL was used for own instruments and JOSE. Finally "Other" includes instrumentation which is not common-user, like CIRSI, INTEGRAL or ELECTRA on the WHT, CIRSI on the INT, or Triffid, Durham Polarimeter and Texas Photometer on the JKT.
Again ISIS and UES are the most used WHT instruments, but with the improved large CCD detectors available, prime focus imaging is becoming very popular. On the INT, dark time periods are becoming almost exclusively used for CCD imaging with the Wide Field Camera and the JKT is rapidly becoming a single instrument telescope for CCD imaging.
Use of instrumentation for semesters 97A+97B WHT ISIS LDSS TAURUS UES PF FOS WYFFOS+Fib GHRIL WHIRCAM Other Total Nights 159 27 22 45 40 2 22 14 12 16 359 % 44.3 7.5 6.1 12.5 11.2 0.6 6.1 3.9 3.3 4.5 100.0
INT PFC/WFC IDS Musicos Other Total Nights 137 169 29 6 341 % 40.2 49.5 8.5 1.8 100.0
JKT CCD RBS Other Total Nights 263 53 28 344 % 76.5 15.4 8.1 100.0 TELESCOPE RELIABILITY
Telescope downtime due to technical problems averaged 2.3, 3.8, and 3.1% on the WHT, the INT, and the JKT respectively in 1997. 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. These continuing low downtime figures should also be assessed against the remarkable increase in observing efficiency that has been accomplished on the INT and the JKT through the re-engineering programme.
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
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