Data challenges of time domain astronomy

Astronomy has been at the forefront of the development of the techniques and methodologies of data intensive science for over a decade with large sky surveys and distributed efforts such as the Virtual Observatory. However, it faces a new data deluge with the next generation of synoptic sky surveys which are opening up the time domain for discovery and exploration. This brings both new scientific opportunities and fresh challenges, in terms of data rates from robotic telescopes and exponential complexity in linked data, but also for data mining algorithms used in classification and decision making. In this paper, we describe how an informatics-based approach-part of the so-called "fourth paradigm" of scientific discovery-is emerging to deal with these. We review our experiences with the Palomar-Quest and Catalina Real-Time Transient Sky Surveys; in particular, addressing the issue of the heterogeneity of data associated with transient astronomical events (and other sensor networks) and how to manage and analyze it.Comment: 15 pages, 3 figures, to appear in special issue of Distributed and Parallel Databases on Data Intensive eScienc

TRY plant trait database – enhanced coverage and open access

Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

A single fast radio burst localized to a massive galaxy at cosmological distance

Fast radio bursts (FRBs) are brief radio emissions from distant astronomical sources. Some are known to repeat, but most are single bursts. Nonrepeating FRB observations have had insufficient positional accuracy to localize them to an individual host galaxy. We report the interferometric localization of the single-pulse FRB 180924 to a position 4 kiloparsecs from the center of a luminous galaxy at redshift 0.3214. The burst has not been observed to repeat. The properties of the burst and its host are markedly different from those of the only other accurately localized FRB source. The integrated electron column density along the line of sight closely matches models of the intergalactic medium, indicating that some FRBs are clean probes of the baryonic component of the cosmic web

Mineral exploration in the Harlech Dome, North Wales

This report presents the results of an airborne geophysical (electromagnetic, magnetic and radiometric) survey of the eastern part of the Harlech Dome, North Wales, and the consequent geological, geochemical and geophysical investigations carried out on the ground and in the laboratory. e The report is divided into two parts. In Part 1 are the regional and general investigations including an account of the airborne geophysical surveys, an investigation into the causes of electromagnetic (EM) anomalies, Curie temperature determinations, the geochemistry and relationships to mineralisation of some igneous rocks in the Harlech Dome, a description of intrusion-breccias in the Harlech Dome, and fluid inclusion studies. In Part 2 are the details of 26 ground investigations carried out to explain the airborne geophysical anomalies. These investigations were of a reconnaissance nature aimed at detecting metal enrichments and explaining the causes of the anomalies rather than at delineating ore bodies. The eastern side of the Harlech Dome contains a folded succession of Cambrian and Ordovician 8 sedimentary, volcanic and intrusive rocks metamorphosed to a low grade. The area has long been a centre of mining activity containing the Dolgellau Gold-belt, in which quartz veins were mined for gold and silver with copper, lead and zinc sulphides, and the porphyry-style copper deposit at Coed-y- Brenin. As reported in Part 1 the airborne magnetic and EM results showed a complex pattern of anomalies, whereas the aeroradiometric data showed little variation. Ground studies of aeromagnetic anomalies demonstrated that they were related either to magnetite present in some sandstones and igneous rocks, I or, more importantly, to pyrrhotite enrichments in several lithologies. Mineralogical studies showed that whilst some enrichments in siltstones and mudstones were probably syngenetic in origin, others were possibly related to epigenetic concentrations produced during vein mineralisation. A study of the I EM anomalies showed that many of them were related to relatively low concentrations ( c 3%) of carbonaceous material or non-commercial quantities of sulphides in the dark mudstones of the Dolgellau Member and Clogau Formation. An interpretation of the radiometric data confirmed that the only indications of uraniferous enrichment occur in the black mudstones of the upper Cambrian Dolgellau I Member. The rock geochemistry study indicated that statistical treatment of rock analyses could be used to distinguish intrusions associated with porphyry-style mineralisation. It also showed that the porphyry- I style mineralisation at Coed-y-Brenin was probably co-genetic with the end-Tremadoc magmatism which gave rise to both the volcanic pile on Rhobell Fawr and intermediate intrusions in the Cambrian, and therefore was quite distinct from the end-Silurian quartz-sulphide vein mineralisation. Intrusion breccias which are also linked to the Rhobell Fawr volcanism were recognised in the area for the first I time. One of them contains the worked-out Glasdir copper deposit. The fluid inclusion study showed differences between quartz veins associated with the vein and disseminated styles of mineralisation, which may be useful in exploration. The ground follow-up work reported in detail in Part 2 showed indications of mineralisation in many of the areas examined. Among these, the possibility of vein and stratabound lead and zinc mineralisation was found at Hengwrt Uchaf and Benglog. At Bryn Coch, Tyddyn Gwladys and Hafod Fraith possible I associated but separate bodies or extensions to the proved porphyry-type copper deposit at Coed-y- Brenin were identified in addition to modest vein mineralisation. In three areas, Mynydd Foe1 Uchaf, Hafod-y-fedw and Y-Gors, dispersed epigenetic sulphide 0 mineralisation in bedrock, mainly pyrrhotite with sub-economic base-metal sulphides, were found. Similar metalliferous concentrations were tentatively identified in a number of other areas including Garth Gel1 where pilot studies were carried out on coincident EM and magnetic anomalies. At Mynydd 1 Bach, Craiglaseithin and Do1 Haidd there are indications of either new veins or extensions to known veins containing copper, lead and zinc as well as feeble disseminated copper mineralisation at the last two localities; again the metal concentrations are considered sub-economic. Ffridd Dol-y-moth and Waun Hir are both drift covered areas which may conceal mineralisation but exploration is hampered by 1 contamination problems. At Nannau, slight copper enrichment was found in volcanic rocks which are believed to be cogenetic with the Coed-y-Brenin porphyry copper deposit. Recommendations are made for further work at Glasdir, in the Coed-y-Brenin area, at Hengwrt 1 Uchaf and Benglog, at Ffridd Dol-y-moth and Nannau and, pending the results of the drainage survey, on the nature and extent of the sulphide concentrations in the Clogau Formation

Cores in Extended Quasars

Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe

Deep Australia Telescope Large Area Survey Radio Observations of the European Large Area ISO Survey S1/Spitzer Wide-Area Infrared Extragalactic Field

We have conducted sensitive (1 σ < 30 μJy) 1.4 GHz radio observations with the Australia Telescope Compact Array of a field largely coincident with infrared observations of the Spitzer Wide-Area Extragalactic Survey. The field is centered on the European Large Area ISO Survey S1 region and has a total area of 3.9°. We describe the observations and calibration, source extraction, and cross-matching to infrared sources. Two catalogs are presented: one of the radio components found in the image and another of radio sources with counterparts in the infrared and extracted from the literature. 1366 radio components were grouped into 1276 sources, 1183 of which were matched to infrared sources. We discover 31 radio sources with no infrared counterpart at all, adding to the class of Infrared-Faint Radio Sources