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The Mosaic 1.1 Imager is populated with thinned, AR coated e2v CCDs. The CCDs are a "deep depletion" variant from e2v for improved red response. A "2-layer" AR coating was chosen for improved blue response relative to the SITe chips used in the previous Mosaic imagers, giving a big advantage in overall exposure time, about 30% shorter for equal S/N in U band. Additionally, the 2-layer coating provides a more uniform depth in all bands (generally limited by U and B) and has a flatter response curve to allow easier photometric transformations. The figure below shows the e2v QE performance relative to the typical SITe CCD previously used in Mosaic 1. The tables below, reproduced from version 4.0 of the manual, provide additional information regarding the read noise, gain, and other properties of the e2v CCDs.

The display orientation of the 16 sections of the Mosaic 1.1 imager at the KPNO 4-meter. The 8 CCDs are divided up into 16 extensions that are labeled in the figure as the numbers in [ ]'s.

A Flat-Field: 4-m R-band Flat

Typical flat-field image (R-band). This raw image shows the good cosmetics and uniform response and sensitivity of the devices. The "rolled-off" edges are caused by filter vignetting.

NOAO is operated by the Association of Universities for Research in Astronomy (AURA), Inc. under cooperative agreement with the National Science Foundation. Last updated Thu Apr 14 14:15 2011

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