Eckhard Sutorius

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 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.

The VISTA Science Archive

We describe the VISTA Science Archive (VSA) and itsfirst public release of data from five of the six VISTA public surveys. The VSA exists to support the VISTA surveys through their lifecycle: the VISTA Public Survey consortia can use it during their quality control assessment of survey data products before submission to the ESO Science Archive Facility (ESO SAF); it supports their exploitation of survey data prior to its publication through the ESO SAF; and, subsequently, it provides the wider community with survey science exploitation tools that complement the data product repository functionality of the ESO SAF. This paper has been written in conjunction with the first public release of public survey data through the VSA and is designed to help its users understand the data products available and how the functionality of the VSA supports their varied science goals. We describe the design of the database and outline the database-driven curation processes that take data from nightly pipeline-processed and calibrated FITS files to create science-ready survey datasets. Much of this design, and the codebase implementing it, derives from our earlier WFCAM Science Archive (WSA), so this paper concentrates on the VISTA-specific aspects and on improvements made to the system in the light of experience gained in operating the WSA.

VISTA data flow system: overview

Data from the two IR survey cameras WFCAM (at UKIRT in the northern hemisphere) and VISTA (at ESO in the southern hemisphere) can arrive at rates approaching 1.4 TB/night for of order 10 years. Handling the data rates on a nightly basis, and the volumes of survey data accumulated over time each present new challenges. The approach adopted by the UKs VISTA Data Flow System (for WFCAM & VISTA data) is outlined, emphasizing how the design will meet the end-to-end requirements of the system, from on-site monitoring of the quality of the data acquired, removal of instrumental artefacts, astrometric and photometric calibration, to accessibility of curated and user-specified data products in the context of the Virtual Observatory. Accompanying papers by Irwin et al and Hambly et al detail the design of the pipeline and science archive aspects of the project.

Archiving multi‐epoch data and the discovery of variables in the near‐infrared

We present a description of the design and usage of a new synoptic pipeline and data base model for time series photometry in the VISTA Data Flow System (VDFS). All UK Infra-Red Telescope Wide Field Camera (UKIRT) data and most of the VISTA main survey data will be processed and archived by the VDFS. Much of these data are multi-epoch, useful for finding moving and variable objects. Our new data base design allows the users to easily find rare objects of these types amongst the huge volume of data being produced by modern survey telescopes. Its effectiveness is demonstrated through examples using Data Release 5 of the UKIRT Deep Infrared Sky Survey (UKIDSS-Deep Extragalactic Survey (DXS) and the Wide Field Camera standard star data. The synoptic pipeline provides additional quality control and calibration to these data in the process of generating accurate light curves. We find that 0.6 ± 0.1 per cent of stars and 2.3 ± 0.6 per cent of galaxies in the UKIDSS-DXS with K 0.015 mag.

VISTA data flow system survey access and curation: the WFCAM science archive

VISTA Data Flow System (VDFS) survey data products are expected to reach of order one petabyte in volume. Fast and flexible user access to these data is pivotal for efficient science exploitation. In this paper, we describe the provision for survey products archive access and curation which is the final link in the data flow system from telescope to user. Science archive development at the Wide Field Astronomy Unit of the Institute for Astronomy within the University of Edinburgh is taking a phased approach. The first phase VDFS science archive is being implemented for WFCAM, a wide-field infrared imager that has similar output to, but at a lower data rate than the VISTA camera. We describe the WFCAM Science Archive, emphasising the design approach that is intended to lead to a scalable archive system that can handle the huge volume of VISTA data.

The UKIRT Hemisphere Survey: definition and J-band data release

This paper defines the UK Infra-red Telescope (UKIRT) Hemisphere Survey (UHS) and release of the complete J-band dataset. The UHS provides continuous coverage in the northern hemisphere from a declination of 0 deg to 60 deg by combining the existing Large Area Survey, Galactic Plane Survey and Galactic Clusters Survey conducted under the UKIRT Infra-red Deep Sky Survey (UKIDSS) programme with a new additional ~12,700 sq.deg area not covered by UKIDSS. This data release includes J-band imaging and source catalogues over the new area, which, together with UKIDSS, completes the J-band UHS coverage over the full ~17,900 sq.deg area. 98 per cent of the data in this release have passed quality control criteria, the remaining 2 per cent being scheduled for re-observation. The median 5-sigma point source sensitivity of the released data is 19.6 mag (Vega). The median full width at half-maximum of the point spread function across the dataset is 0.75 arcsec. In this paper, we outline the survey management, data acquisition, processing and calibration, quality control and archiving as well as summarising the characteristics of the released data products. The data are initially available to a limited consortium with a world-wide release scheduled for August 2018.

The VMC survey I. Strategy and first data

Context. The new VISual and Infrared Telescope for Astronomy (VISTA) has started operations. Over its first five years it will be col lecting data for six Public Surveys, one of which is the near-infrared Y JKs VISTA survey of the Magellanic Clouds system (VMC). This survey comprises the Large Magellanic Cloud (LMC), the Small Magellanic Cloud, the Magellanic Bridge connecting the two galaxies and two fields in the Magellanic Stream. Aims. This paper provides an overview of the VMC survey strategy and presents first science results. The main goals of the VMC sur vey are the determination of the spatially-resolved star-form ation history and the three-dimensional structure of the Magellanic system. The VMC survey is therefore designed to reach stars as faint as the ol dest main sequence turn-off point and to constrain the mean magnitude of pulsating variables such as RR Lyrae stars and Cepheids. This paper focuses on observations of VMC fields in the LMC obtained between November 2009 and March 2010. These observations correspond to a completeness of 7% of the planned LMC fields. Methods. The VMC data are comprised of multi-epoch observations which are executed following specific time constraints. The data were reduced using the VISTA Data Flow System pipeline with source catalogues, including astrometric and photometric corrections, produced and made available via the VISTA Science Archive. The VMC data will be released to the astronomical community following the European Southern Observatory’s Public Survey policy. The analysis of the data shows that the sensitivity in each wave band agrees with expectations. Uncertainties and completeness of the data are also derived. Results. The first science results, aimed at assessing the scientific q uality of the VMC data, include an overview of the distribution of stars in colour-magnitude and colour-colour diagrams, the detection of planetary nebulae and stellar clusters, and the Ks band light-curves of variable stars. Conclusions. The VMC survey represents a tremendous improvement, in spatial resolution and sensitivity, on previous panoramic observations of the Magellanic system in the near-infrared, providing a powerful complement to deep observations at other wavelengths.

Science Archives at the Wide Field Astronomy Unit

The Wide Field Astronomy Unit (WFAU) at the Royal Observatory, Edinburgh (ROE) has been producing archives of astronomy data for more than a decade. It houses a collection of over 80 billion individual detections spread across five major astronomical surveys dating back over 60 years. As well as these surveys, we also host copies of external surveys to allow the cross-referencing of sources in our surveys with those detected with other instruments. This article details the data held by WFAU and the services we provide to our users.