The Liverpool Telescope is sited 2363m above sea level at the Roque de Los Muchachos, on the island of La Palma, the westernmost of the Canary Islands. Many European observatories have been built at this site under the umbrella organisation of the Observatorio del Roque de Los Muchachos ("ORM"). The Roque is one of the best observing sites in the world, with low levels of light pollution, median seeing of 0.8 arcseconds, and more than 80 per cent of nights are photometric.
For Liverpool Telescope 2 we considered a number of different sites, and settled on the ORM. Building the new telescope on the same site as the existing LT has logistical advantages, but we also envisage scientific benefits from the combined operation of the two telescopes as a single facility. We plan to replace the instrument suite on the Liverpool Telescope with a single, prime focus imager offering a 2 square degree field-of-view, and operate both telescopes as a single facility. This enabling simultaneous photometry and spectroscopy of time critical objects such as rapidly-fading transients, and the localisation of transients detected by other facilities but with a large positional uncertainty, such as gravitational wave counterparts.
An important factor when choosing a site is the sky overlap with other facilities. The ORM is a northern hemisphere site, but at a latitude of +28.8 degrees a considerable fraction of the southern sky is also available. For example, objects with a declination as low as -30 degrees can be observed at an airmass less than 2. This means that LT2 will be able to observe a significant fraction of transients discovered by Southern Hemisphere facilities such as LSST or SKA. LSST is expected to report millions of time variable objects per night, so even from a Northern site LT2 will have to be quite selective in choosing which LSST detections to follow-up.