Testing is underway on the SITe CCDs that will replace the engineering-grade chips in the Mosaic Imager this summer. Preliminary reports are encouraging; the chips tested so far show read noise in the 3-6 e- range and good charge transfer efficiency and cosmetic quality. The QE curves are typical of SITe CCDs (such as T2KB) with peak sensitivity around 80% at 600 nm, dropping to about 40% at 350 nm. This represents a huge gain over the chips currently in the Mosaic Imager, particularly in the blue. Barring unforeseen difficulties, the new CCDs will be installed in June and will be tested on the 4-m telescope in mid-July.
The demand for the Mosaic Imager in the most recent round of proposals (1998B) was heavy. Twenty-seven proposals requested 94 nights on the 4-m telescope and 31 proposals requested 139 nights on the 0.9-m telescope.
Our filter collection for Mosaic continues to grow. By next semester, we expect to have broad-band filters: U, B, V, R, I, as well as g, r, i, and z' from the Gunn/SDSS system. We will also have various narrow-band filters for [O III] and Ha observations. See the Mosaic filter list at http://www.noao.edu/kpno/mosaic/filters/filters.html for the most recent information.
The latest information about the CCD Mosaic Imager and the most current version of the user manual can be found at the Mosaic Web Site (http://www.noao.edu/kpno/mosaic/mosaic.html).
Todd Boroson (for the Mosaic Team)