Nigel Hambly

The UKIRT infrared deep sky survey (UKIDSS)

Final published version including significant revisions. Twenty four pages, fourteen figures. Original version April 2006; final version published in MNRAS August 2007

A luminous quasar at a redshift of z = 7.085

The intergalactic medium was not completely reionized until approximately a billion years after the Big Bang, as revealed by observations of quasars with redshifts of less than 6.5. It has been difficult to probe to higher redshifts, however, because quasars have historically been identified in optical surveys, which are insensitive to sources at redshifts exceeding 6.5. Here we report observations of a quasar (ULAS J112001.48+064124.3) at a redshift of 7.085, which is 0.77 billion years after the Big Bang. ULAS J1120+0641 has a luminosity of 6.3 × 1013L⊙ and hosts a black hole with a mass of 2 × 109M⊙ (where L⊙ and M⊙ are the luminosity and mass of the Sun). The measured radius of the ionized near zone around ULAS J1120+0641 is 1.9 megaparsecs, a factor of three smaller than is typical for quasars at redshifts between 6.0 and 6.4. The near-zone transmission profile is consistent with a Lyα damping wing, suggesting that the neutral fraction of the intergalactic medium in front of ULAS J1120+0641 exceeded 0.1.

The Third US Naval Observatory CCD Astrograph Catalog (UCAC3)

The second US Naval Observatory (USNO) CCD Astrograph Catalog, UCAC2 was released in 2003 July. Positions and proper motions for 48,330,571 sources (mostly stars) are available on 3 CDs, supplemented with Two Micron All Sky Survey photometry for 99.5% of the sources. The catalog covers the sky area from -90° to +40° declination, going up to +52° in some areas; this completely supersedes the UCAC1 released in 2001. Current epoch positions are obtained from observations with the USNO 8 inch (0.2 m) Twin Astrograph equipped with a 4K CCD camera. The precision of the positions are 15–70 mas, depending on magnitude, with estimated systematic errors of 10 mas or below. Proper motions are derived by using over 140 ground- and space-based catalogs, including Hipparcos/Tycho and the AC2000.2, as well as yet unpublished remeasures of the AGK2 plates and scans from the NPM and SPM plates. Proper-motion errors are about 1–3 mas yr-1 for stars to 12th magnitude, and about 4–7 mas yr-1 for fainter stars to 16th magnitude. The observational data, astrometric reductions, results, and important information for the users of this catalog are presented.

The SuperCOSMOS Sky Survey – I. Introduction and description

In this, the first in a series of three papers concerning the SuperCOSMOS Sky Survey (SSS), we give an introduction and user guide to the survey programme. We briefly describe other wide-field surveys and compare them with our own. We give examples of the data, and make a comparison of the accuracies of the various image parameters available with those from the other surveys providing similar data; we show that the SSS data base and interface offer advantages over these surveys. Some science applications of the data are also described and some limitations discussed. The series of three papers constitutes a comprehensive description and user guide for the SSS.

Gaia Data Release 1 - Astrometry: one billion positions, two million proper motions and parallaxes

Gaia Data Release 1 (Gaia DR1) contains astrometric results for more than 1 billion stars brighter than magnitude 20.7 based on observations collected by the Gaia satellite during the first 14 months of its operational phase. We give a brief overview of the astrometric content of the data release and of the model assumptions, data processing, and validation of the results. For stars in common with the Hipparcos and Tycho-2 catalogues, complete astrometric single-star solutions are obtained by incorporating positional information from the earlier catalogues. For other stars only their positions are obtained by neglecting their proper motions and parallaxes. The results are validated by an analysis of the residuals, through special validation runs, and by comparison with external data. Results. For about two million of the brighter stars (down to magnitude ~11.5) we obtain positions, parallaxes, and proper motions to Hipparcos-type precision or better. For these stars, systematic errors depending e.g. on position and colour are at a level of 0.3 milliarcsecond (mas). For the remaining stars we obtain positions at epoch J2015.0 accurate to ~10 mas. Positions and proper motions are given in a reference frame that is aligned with the International Celestial Reference Frame (ICRF) to better than 0.1 mas at epoch J2015.0, and non-rotating with respect to ICRF to within 0.03 mas/yr. The Hipparcos reference frame is found to rotate with respect to the Gaia DR1 frame at a rate of 0.24 mas/yr. Based on less than a quarter of the nominal mission length and on very provisional and incomplete calibrations, the quality and completeness of the astrometric data in Gaia DR1 are far from what is expected for the final mission products. The results nevertheless represent a huge improvement in the available fundamental stellar data and practical definition of the optical reference frame.

VISTA Variables in the Via Lactea (VVV): The public ESO near-IR variability survey of the Milky Way

Original article can be found at: http://www.sciencedirect.com/science/journal/13841076 Copyright Elsevier B.V.

The WFCAM Science Archive

We describe the WFCAM Science Archive, which is the primary point of access for users of data from the wide-field infrared camera WFCAM on the United Kingdom Infrared Telescope (UKIRT), especially science catalogue products from the UKIRT Infrared Deep Sky Survey. We describe the database design with emphasis on those aspects of the system that enable users to fully exploit the survey data sets in a variety of different ways. We give details of the database-driven curation applications that take data from the standard nightly pipeline-processed and calibrated files for the production of science-ready survey data sets. We describe the fundamentals of querying relational databases with a set of astronomy usage examples, and illustrate the results.

The AAO/UKST SuperCOSMOS Hα survey

The UK Schmidt Telescope (UKST) of the Anglo-Australian Observatory completed a narrowband Ha plus [N II] 6548, 6584-A survey of the Southern Galactic Plane and Magellanic Clouds in late 2003. The survey, which was the last UKST wide-field photographic survey and the only one undertaken in a narrow-band, is now an online digital data product of the Wide-Field Astronomy Unit of the Royal Observatory Edinburgh (ROE). The survey utilized a high specification, monolithic Hα interference bandpass filter of exceptional quality. In conjunction with the fine-grained Tech-Pan film as a detector it has produced a survey with a powerful combination of area coverage (4000 square degrees), resolution (∼1 arcsec) and sensitivity (≤5 Rayleighs), reaching a depth for continuum point sources of R ≃ 20.5. The main survey consists of 233 individual fields on a grid of centres separated by 4° at declinations below +2° and covers a swathe approximately 20° wide about the Southern Galactic Plane. The original survey films were scanned by the SuperCOSMOS measuring machine at the Royal Observatory, Edinburgh, to provide the online digital atlas called the SuperCOSMOS Ha Survey (SHS). We present the background of the survey, the key survey characteristics, details and examples of the data product, calibration process, comparison with other surveys and a brief description of its potential for scientific exploitation.

The UKIRT Infrared Deep Sky Survey Early Data Release

This paper defines the UKIRT Infrared Deep Sky Survey (UKIDSS) Early Data Release (EDR). UKIDSS is a set of five large near-infrared surveys being undertaken with the United Kingdom Infrared Telescope Wide Field Camera (WFCAM). The programme began in 2005 May and has an expected duration of 7 yr. Each survey uses some or all of the broad-band filter complement ZY JHK. The EDR is the first public release of data to the European Southern Observatory (ESO) community. All worldwide releases occur after a delay of 18 months from the ESO release. The EDR provides a small sample data set, ∼50 deg(2) (about 1 per cent of the whole of UKIDSS), that is a lower limit to the expected quality of future survey data releases. In addition, an EDR+ data set contains all EDR data plus extra data of similar quality, but for areas not observed in all of the required filters (amounting to ∼220 deg(2)). The first large data release, DR1, will occur in mid-2006. We provide details of the observational implementation, the data reduction, the astrometric and photometric calibration and the quality control procedures. We summarize the data coverage and quality (seeing, ellipticity, photometricity, depth) for each survey and give a brief guide to accessing the images and catalogues from the WFCAM Science Archive.

The United Kingdom Infrared Telescope Infrared Deep Sky Survey First Data Release

The First Data Release (DR1) of the UKIRT Infrared Deep Sky Survey (UKIDSS) took place on 2006 July 21. UKIDSS is a set of five large near–infrared surveys, covering a complementary range of areas, depths, and Galactic latitudes. DR1 is the first large release of survey-quality data from UKIDSS and includes 320 deg of multicolour data to (Vega) K = 18, complete (depending on the survey) in three to five bands from the set ZYJHK, together with 4 deg of deep JK data to an average depth K = 21. In addition the release includes a similar quantity of data with incomplete filter coverage. In JHK, in regions of low extinction, the photometric uniformity of the calibration is better than 0.02mag. in each band. The accuracy of the calibration in ZY remains to be quantified, and the same is true of JHK in regions of high extinction. The median image FWHM across the dataset is 0.82. We describe changes since the Early Data Release in the implementation, pipeline and calibration, quality control, and archive procedures. We provide maps of the areas surveyed, and summarise the contents of each of the five surveys in terms of filters, areas, and depths. DR1 marks completion of 7 per cent of the UKIDSS 7-year goals.