Near-Infrared Observations
The near-infrared images have been collected at the UKIRT telescope (Mauna Kea) with the WFCAM instrument during four different runs in 2005 and 2006:
The camera consists of 4 Rockwell Hawaii-II (HgCdTe 2048x2048) arrays spaced by 94% in the focal plane, such that 4 separately pointed observations can be tiled together to cover a filled square of sky covering 0.75 square degrees with 0.4 arcsecond pixels. A fixed auto-guider array is installed in the centre. The cameras are numbered from 1 to 4 from the bottom-right in counterclockwise direction. A single exposure covers an area of 0.19 sq. degrees, while 4 exposures cover an area of 0.75 sq. degrees.
The original plan of WINGS-NIR survey was to image at least all the WINGS clusters with spectroscopy and visible by UKIRT: unfortunately the bad weather (see table above) limited the sample to only 28 clusters. Anyway, as it can be seen in the figure below, the NIR subsample (red line) has a good coverage of X-ray luminosities and redshifts if compared with the total WINGS sample (black dotted line, slightly shifted for better view), while it is slightly biased towards the low cluster velocity dispersion regime.
Filters equipment of UKIRT-WFCAM instrument: please note that the K filter is not a KS filter.
