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Results Change page style: Cloud Cover Statistics Data logged
nightly by the UKIRT Telescope Operators over a ten-year period
(1985 September 13 to 1996 August 4) have been analysed. Their
reporting includes cloud cover (in eighths), cloud type and the
number of usable and available hours. The data may be summarised
thus: Usable time: excluding nights for which no information was
available (e.g. due to telescope shutdown) approximately three-
quarters of the available time (31419 out of 43427 hr) was
identified as "usable" i.e. the telescope was open and data were
collected. Cloudless: of the usable time 62% (19371 hr) was
noted as being "cloudless". It is recognised that this is a
subjective assessment e.g.