The allocation of time on telescopes in which the UK has share, (such as the Anglo-Australian Telescope, the William Herschel Telescope, the Isaac Newton Telescope, the Jacobus Kaptyen Telescope, James Clerk Maxwell Telescope and the United Kingdom Infrared Telescope), is decided by a system of peer review, through the Panel for the Allocation of Telescope Time (PATT).
The year is split up into two semesters (February - July and August - January) and the semester chosen depends on the objects to be observed. The applicant fills in a standard PATT form, which requests information about the objects to be observed and the instruments required for the observation, as well as requiring a scientific justification for the proposed project. On the basis of the scientific case and the technical feasibility of the project the PATT panel selects which projects should be allocated telescope time. All telescopes are heavily over-subscribed, so that only the highest-rated proposals are awarded time. The deadlines for receipt of proposals are September 30 and March 31 and those from ATC and University personnel are dispatched by courier a day or two before the deadline.
The procedure outlined above covers observational projects that require one night or more of telescope time. Projects requiring no more than a few hours may be performed in ``Service Time'' by staff astronomers, rather than the scientists who proposed the project. Service observations are also subject to peer review to decide which should be undertaken.
Collaboration with astronomers from other countries can enable one to have access to telescopes in which the UK has no financial share. Other facilities eg. HST and other satellites, the VLA, Merlin etc., also make their time available to UK astronomers. These have different applications procedures and deadlines from those administered by PATT, but also decide telescope allocation through peer review.