Context. The infrared wide-field camera (WFCAM) is now in operation on the 3.8 m UK Infrared Telescope on Mauna Kea. WFCAM currently has the fastest survey speed of any infrared camera in the world, and combined with generous allocations of telescope time, will produce deep maps of the sky from Z to K band. The data from a set of public surveys, known as UKIDSS, will be initially available to astronomers in ESO member states, and later to the world. Aims. In order to maximise survey speed, the WFCAM field of view was required to be as large as possible while incorporating conventional infrared-instrument design features such as a cold re-imaged pupil stop and cryogenic optics and mechanisms. Methods. The solution adopted was to build a cryogenic Schmidt-type camera, mounted forward of the primary mirror, which illuminates a very large 0.9• diameter focal plane, containing four 2k × 2k HgCdTe Rockwell detectors. Results. Following several commissioning periods during which the camera, focal plane and telescope optical axes were successfully co-aligned, WFCAM now operates close to specifications, regularly achieving 0.7 FWHM images over the full field. Projects which already report excellent results include the detection of variability in young stellar clusters, as well as preliminary deep IR imaging of the Subaru and XMM-Newton deep field.

Context. The afterglows and host galaxies of long gamma-ray bursts (GRBs) offer unique opportunities to study star-forming galaxies in the high-z Universe. Until recently, however, the information inferred from GRB follow-up observations was mostly limited to optically bright afterglows, biasing all demographic studies against sight-lines that contain large amounts of dust. Aims. Here we present afterglow and host observations for a sample of bursts that are exemplary of previously missed ones because of high visual extinction (A GRB V 1 mag) along the sight-line. This facilitates an investigation of the properties, geometry, and location of the absorbing dust of these poorly-explored host galaxies, and a comparison to hosts from optically-selected samples. Methods. This work is based on GROND optical/NIR and Swift/XRT X-ray observations of the afterglows, and multi-color imaging for eight GRB hosts. The afterglow and galaxy spectral energy distributions yield detailed insight into physical properties such as the dust and metal content along the GRB sight-line and galaxy-integrated characteristics such as the host's stellar mass, luminosity, color-excess, and star-formation rate. Results. For the eight afterglows considered in this study, we report for the first time the redshift of GRB 081109 (z = 0.9787±0.0005), and the visual extinction towards GRBs 081109 (A GRB V = 3.4 +0.4 −0.3 mag) and 100621A (A GRB V = 3.8 ± 0.2 mag), which are among the largest ever derived for GRB afterglows. Combined with non-extinguished GRBs, there is a strong anti-correlation between the afterglow's metal-to-dust ratio and visual extinction. The hosts of the dustiest afterglows are diverse in their properties, but on average redder ( (R − K) AB ∼ 1.6 mag), more luminous ( L ∼ 0.9 L * ), and massive ( log M * [M ] ∼ 9.8) than the hosts of optically-bright events. Hence, we probe a different galaxy population, suggesting that previous host samples miss most of the massive and metal-rich members. This also indicates that the dust along the sight-line is often related to host properties, and thus probably located in the diffuse ISM or interstellar clouds and not in the immediate GRB environment. Some of the hosts in our sample, are blue, young, or of low stellar mass illustrating that even apparently non-extinguished galaxies possess very dusty sight-lines owing to a patchy dust distribution. Conclusions. The afterglows and host galaxies of the dustiest GRBs provide evidence of a complex dust geometry in star-forming galaxies. In addition, they establish a population of luminous, massive, and correspondingly chemically evolved GRB hosts. This suggests that GRBs trace the global star-formation rate better than studies based on optically selected host samples indicate, and that the previously claimed deficiency of high-mass hosts was at least partially a selection effect.

The Deep Ecliptic Survey ( DES)-a search optimized for the discovery of Kuiper belt objects ( KBOs) with the Blanco and Mayall 4 m telescopes at the Cerro Tololo Inter-American Observatory and Kitt Peak National Observatory-has covered 550 deg 2 from its inception in 1998 through the end of 2003. This survey has a mean 50% sensitivity at VR magnitude 22.5. We report here the discoveries of 320 designated KBOs and Centaurs for the period 2000 March through 2003 December and describe improvements to our discovery and recovery procedures. Our data and the data products needed to reproduce our analyses in this paper are available through the NOAO survey database. Here we present a dynamical classification scheme, based on the behavior of orbital integrations over 10 Myr. The dynamical classes, in order of testing, are ''Resonant,'' ''Centaur,'' ''Scattered-Near,'' ''Scattered-Extended,'' and ''Classical.'' ( These terms are capitalized when referring to our rigorous definitions.) Of the 382 total designated KBOs discovered by the DES, a subset of 196 objects have sufficiently accurate orbits for dynamical classification. Summary information is given for an additional 240 undesignated objects also discovered by the DES from its inception through the end of 2003. The number of classified DES objects (uncorrected for observational bias) are Classical, 96; Resonant, 54; Scattered-Near, 24; Scattered-Extended, 9; and Centaur, 13. We use subsets of the DES objects (which can have observational biases removed ) and larger samples to perform dynamical analyses on the Kuiper belt. The first of these is a determination of the Kuiper belt plane ( KBP), for which the Classical objects with inclinations less than 5 from the mean orbit pole yield a pole at R.A. = 273N92 AE 0N62 and decl. = 66N70 AE 0N20 (J2000), consistent with the invariable plane of the solar system. A general method for removing observational biases from the DES data set is presented and used to find a provisional magnitude distribution and the distribution of orbital inclinations relative to the KBP. A power-law model fit to the cumulative magnitude distribution of all KBOs discovered by the DES in the VR filter yields an index of 0:86 AE 0:10 (with the efficiency parameters for the DES fitted simultaneously with the population power law). With the DES sensitivity parameters fixed, we derive power-law indices of 0:74 AE 0:05, 0:52 AE 0:08, and 0:74 AE 0:15, respectively, for the Classical, Resonant, and Scattered classes. Plans for calibration of the DES detection efficiency function and DES magnitudes are discussed. The inclination distribution confirms the presence of ''hot'' and ''cold'' populations; when the geometric sin i factor is removed from the inclination distribution function, the cold population shows a concentrated ''core'' with a full width at half-maximum of approximately 4N6, while the hot population appears as a ''halo, '' extending beyond 30 . The inclination distribution is used to infer the KBO distribution in the sky, as a func...