A clone of the 8K Mosaic Imager presently in use at the KPNO Mayall and 0.9-m telescopes will be commissioned at the Blanco prime focus during 1999. This new facility instrument replaces the Big Throughput Camera, previously available through a collaboration with Tony Tyson and Gary Bernstein.
The dewar (with engineering grade devices) and filter assembly have already been received at CTIO. The eight SITe 2K × 4K CCDs for Mosaic II are being tested in the Tucson CCD Lab during early 1999. After assembly of the science-grade focal plane, the CCDs will be taken to CTIO and installed in the dewar, to be followed by full system tests. Concurrently, we will modify the prime focus area, strengthening the pedestal and enlarging the cage doors. Mosaic II is scheduled to be put on the 4-m for engineering tests on 12 July. It is planned to be available for general visitor use for Semester 1999B, with the caveat that we intend to restrict access during August when we plan a second engineering run.
Since Mosaic II is a clone of Mosaic I, much of the extensive documentation available for the latter is directly relevant.You can find this at: http://www.noao.edu/kpno/mosaic/manual or via a link from the CTIO Optical Instruments page http://www.ctio.noao.edu/instruments/optical_instruments.html.
Information on aspects that are different between the two installations (e.g. filters available) will be found via the CTIO address, and we will continue to add more information, such as CCD properties, as it becomes available.
Mosaic II will not be offered at any telescope apart from the 4-m prime focus. Mosaic II offers a finer pixel scale than the BTC, and there has been little demand and no scheduled use of Cass focus CCD imaging in recent semesters. Hence we will no longer offer CCD imaging at Cass focus. The Mosaic II at prime focus will be the only optical imager scheduled at the Blanco 4-m.
Alistair Walker (awalker@noao.edu)