UKIRT Wide Field Camera Research Articles

Robust autonomous detection of the defective pixels in detectors using a probabilistic technique

Detection of defective pixels in solid-state detectors/sensor arrays has received limited research attention. Few approaches currently exist for detecting the defective pixels using real images captured with cameras equipped with such detectors, and they are ad hoc and limited in their applicability. In this paper, we present a probabilistic novel integrated technique for autonomously detecting the defective pixels in image sensor arrays. It can be applied to images containing rich scene information, captured with any digital camera equipped with a solid-state detector, to detect different kinds of defective pixels in the detector. We apply our technique to the detection of various defective pixels in an experimental camera equipped with a charge coupled device (CCD) array and two out of the four HgCdTe detectors of the UKIRT's wide field camera (WFCAM) used for infrared (IR) astronomy [Astron. Astrophys.467, 777-784 (2007)].

The UKIRT Infrared Deep Sky Survey ZY JHK photometric system: passbands and synthetic colours

The UKIRT Infrared Deep Sky Survey is a set of five surveys of complementary combinations of area, depth, and Galactic latitude, which began in 2005 May. The surveys use the UKIRT Wide Field Camera (WFCAM), which has a solid angle of 0.21deg^2. Here we introduce and characterise the ZYJHK photometric system of the camera, which covers the wavelength range 0.83-2.37 microns. We synthesise response functions for the five passbands, and compute colours in the WFCAM, SDSS and 2MASS bands, for brown dwarfs, stars, galaxies and quasars of different types. We provide a recipe for others to compute colours from their own spectra. Calculations are presented in the Vega system, and the computed offsets to the AB system are provided, as well as colour equations between WFCAM filters and the SDSS and 2MASS passbands. We highlight the opportunities presented by the new Y filter at 0.97-1.07 microns for surveys for hypothetical Y dwarfs (brown dwarfs cooler than T), and for quasars of very--high redshift, z>6.4.