An enhancement of the capabilities for CCD imaging at the WIYN telescope is underway. The imager CCD (S2KB), a 2048 × 2048 SITe/STIS device, is being replaced. The new imager is a pair of thinned, backside illuminated, anti-reflection coated 2048 × 4096 SITe devices, arranged to mimic a 4096 × 4096 array. These SITe CCDs are identical to those used in the NOAO CCD Mosaic Imager and are of equally high quality. For information on CCD performance (for example, quantum efficiency curves), see the Users' Manual for the CCD Mosaic Imager (http://www.noao.edu/kpno/mosaic/manual). Each 15 µm pixel corresponds to 0.141", yielding a field size of 9.6' × 9.6'. The two CCDs are read out through a total of four amplifiers using a HArcon controller (a hybrid Arcon). The readout noise values of the four amplifiers are 5.5 e-, 5.3 e-, 5.4 e-, and 5.5 e-. The average gain value is 1.4 e- per data number. Observations are controlled via the same version of the Arcon software as is used with the NOAO CCD Mosaic Imager. Other properties of the WIYN imager, such as the filter wheel, available filters, the shutter, and guiding remain unchanged.
At the end of April, we had two nights of testing at WIYN during which many critical aspects of the system's on-sky performance were successfully tested. Once the commissioning process is completed, the MiniMosaic will be available for regular science observations. Astronomers who have approved WIYN imaging programs will be contacted and queried about the implications of using MiniMosaic for your observations.
Many individuals from the Optical/UV Engineering Group, the Mountain Programming Group, the CTIO Arcon team, and the IRAF Group have made important contributions to the success of the MiniMosaic project.
Taft Armandroff, Abi Saha