DAME: A distributed data mining and exploration framework within the virtual observatory

Nowadays, many scientific areas share the same broad requirements of being able to deal with massive and distributed datasets while, when possible, being integrated with services and applications. In order to solve the growing gap between the incremental generation of data and our understanding of it, it is required to know how to access, retrieve, analyze, mine and integrate data from disparate sources. One of the fundamental aspects of any new generation of data mining software tool or package which really wants to become a service for the community is the possibility to use it within complex workflows which each user can fine tune in order to match the specific demands of his scientific goal. These workflows need often to access different resources (data, providers, computing facilities and packages) and require a strict interoperability on (at least) the client side. The project DAME (DAta Mining & Exploration) arises from these requirements by providing a distributed WEB-based data mining infrastructure specialized on Massive Data Sets exploration with Soft Computing methods. Originally designed to deal with astrophysical use cases, where first scientific application examples have demonstrated its effectiveness, the DAME Suite results as a multi-disciplinary platformindependent tool perfectly compliant with modern KDD (Knowledge Discovery in Databases) requirements and Information & Communication Technology trends

Mining the SDSS archive. I. Photometric redshifts in the nearby universe

We present a supervised neural network approach to the determination of photometric redshifts. The method was tuned to match the characteristics of the Sloan Digital Sky Survey and it exploits the spectroscopic redshifts provided by this unique survey. In order to train, validate and test the networks we used two galaxy samples drawn from the SDSS spectroscopic dataset: the general galaxy sample (GG) and the luminous red galaxies subsample (LRG). The method consists of a two steps approach. In the first step, objects are classified in nearby (z<0.25) and distant (0.25<z<0.50). In the second step two different networks are separately trained on objects belonging to the two redshift ranges. Using a standard MLP operated in a Bayesian framework, the optimal architectures were found to require 1 hidden layer of 24 (24) and 24 (25) neurons for the GG (LRG) sample. The presence of systematic deviations was then corrected by interpolating the resulting redshifts. The final results on the GG dataset give a robust sigma_z = 0.0208 over the redshift range [0.01, 0.48] and sigma_z = 0.0197 and sigma_z = 0.0238 for the nearby and distant samples respectively. For the LRG subsample we find a robust sigma_z = 0.0164 over the whole range, and sigma_z = 0.0160, sigma_z = 0.0183 for the nearby and distant samples respectively. After training, the networks have been applied to all objects in the SDSS Table GALAXY matching the same selection criteria adopted to build the base of knowledge, and photometric redshifts for ca. 30 million galaxies having z<0.5 were derived. A catalogue containing photometric redshifts for the LRG subsample was also produced.Comment: 45 pages, 14 figures, accepted for publication is the Astrophysical Journa

Evaluating High Impact Papers: Are We Missing Something?

The bibliographic science papers with high citations rates are often used as an indication of the science impact of an observatory. These high impact papers are presented as examples of the best science being done with an observatory’s data. But, is the number of citations by itself a good indicator of the scientific impact of the paper, and is impact a good indicator of the scientific impact of the observatory? In this paper we will present results from a recent study of Chandra high impact papers and suggest some alternative methods for identifying such papers. This work has been supported by NASA under contract NAS 8-03060 to the Smithsonian Astrophysical Observatory for operation of the Chandra X-ray Center

Growing a Bibliography

The Chandra Data Archive (CDA) has been tracking publications based on Chandra observations in journals and on-line conference proceedings since early in the mission. Our goals are two-fold: 1) provide a means for Chandra users to search literature on Chandra-related papers to further their scientific research; and 2) provide a means for measuring the science produced from Chandra data. Over the years the database and its associated tools have expanded dramatically. In this paper I will give a history of the development of the bibliography with a focus on the human capital involved, along with the skill sets and management structures developed which allow us to maintain a very rich and extensive bibliography with a limited number of full time employees (FTEs). I will also cover how the diverse metadata collected has made the Chandra bibliography an essential resource in managing the Chandra X-ray Center. This work has been supported by NASA under contract NAS 8-03060 to the Smithsonian Astrophysical Observatory for operation of the Chandra X-ray Center. It depends critically on the services provided by the ADS

Growing a Bibliography

The Chandra Data Archive (CDA) has been tracking publications based on Chandra observations in journals and on-line conference proceedings since early in the mission. Our goals are two-fold: 1) provide a means for Chandra users to search literature on Chandra-related papers to further their scientific research; and 2) provide a means for measuring the science produced from Chandra data. Over the years the database and its associated tools have expanded dramatically. In this paper I will give a history of the development of the bibliography with a focus on the human capital involved, along with the skill sets and management structures developed which allow us to maintain a very rich and extensive bibliography with a limited number of full time employees (FTEs). I will also cover how the diverse metadata collected has made the Chandra bibliography an essential resource in managing the Chandra X-ray Center. This work has been supported by NASA under contract NAS 8-03060 to the Smithsonian Astrophysical Observatory for operation of the Chandra X-ray Center. It depends critically on the services provided by the ADS

Optical Spectroscopic Observations of Gamma-Ray Blazar Candidates. XII. Follow-up Observations from SOAR, Blanco, NTT, and OAN-SPM

Roughly one third of the sources in the Fermi-LAT catalogs are listed as unidentified/unassociated γ-ray sources (UGS), i.e., they lack a low-energy counterpart. In addition, there is a growing population of blazars of uncertain type (BCUs). Spectroscopic observations are crucial to confirm the blazar nature of the UGSs candidate counterparts and BCUs. Hence, in 2013 we started an optical spectroscopic campaign to carry out the identifications and classifications. In this paper, as a continuation of the campaign we report the spectra of 39 sources: the sample comprises 37 sources classified as BCUs, one source classified as a BL Lac in the Fourth Source Catalog of the Fermi-LAT (4FGL), and one source classified as UGS. We classify 19 of the sources in the sample as BL Lacs, 13 as blazars with nonnegligible host-galaxy emission, six as Flat Spectrum Radio Quasars, and one as a normal elliptical galaxy. The source listed as BL Lac in the 4FGL seems to be a blazar with nonnegligible host-galaxy emission in our observations, most likely due to an ongoing quiescent state. We classified the UGS source as a BL Lac. Six out of the 39 sources were previously reported in the campaign; in general, both the classifications and redshifts are in agreement, except for one of them with no redshift reported before. Altogether, we provided reliable redshift estimates to 21 out of the 39 sources. Finally, we describe the statistics of the data collected in our campaign so far

The Fornax Deep Survey (FDS) with VST

Not Availabl

Long term aspects of landfilling and surface disposal : Lessons learned from nuclear and non-nuclear decommissioning, remediation and waste management

The fields of landfilling of conventional waste and that of surface disposal of nuclear waste have developed quite independently and also partly out of phase with each other. The paper analyses what knowledge and experience might be mutually beneficial as well as what further knowledge may be needed.It is found that even though knowledge may exist, and information from lessons learned elsewhere be available, action may be subject to considerable initiation or incubation times. Legislation on financial reporting is summarized and its implications for early technical and financial planning are assessed. Prerequisites for long-term behaviour are analysed for the waste forms as well as for the seals and covers. The rationale for using natural and anthropogenic analogues is compiled, and alternative seals for landfills are analysed based on this information. Lessons learned from nuclear decommissioning are presented, and the difficulties encountered when the decommissioning takes place long times after commissioning and operation of a facility are illuminated. Comparison is made with contaminated soil in which area openly available domestic publications are lass abundant in some areas. The differences between end of license and end of responsibilities are clarified. Uranium-containing waste is presented as an example. Prerequisites are presented for natural uranium together with its progenies and for depleted uranium, initially without any daughters. It is found that both alternatives are associated with a number of issues to consider, and that both call for long-term containment for conventional chemical hazard and radiological hazard reasons.Validerad; 2013; 20130806 (laan)</p

The Fornax Deep Survey with VST:IX. Catalog of sources in the FDS area with an example study for globular clusters and background galaxies

Abstract Context: A possible pathway for understanding the events and the mechanisms involved in galaxy formation and evolution is an in-depth investigation of the galactic and inter-galactic fossil sub-structures with long dynamical timescales: stars in the field and in stellar clusters. Aims: This paper continues the Fornax Deep Survey (FDS) series. Following previous studies dedicated to extended Fornax cluster members, we present the catalogs of compact stellar systems in the Fornax cluster, as well as extended background sources and point-like sources. Methods: We derived ugri photometry of ∼1.7 million sources over the ∼21 square degree area of FDS centered on the bright central galaxy NGC 1399. For a wider area, of ∼27 square degrees extending in the direction of NGC 1316, we provided gri photometry for ∼3.1 million sources. To improve the morphological characterization of sources, we generated multi-band image stacks by coadding the best-seeing gri-band single exposures with a cut at full width at half maximum (FWHM) ≤ 0.″9. We used the multi-band stacks as master detection frames, with a FWHM improved by ∼15% and a FWHM variability from field to field reduced by a factor of ∼2.5 compared to the pass-band with the best FWHM, namely the r-band. The identification of compact sources, in particular, globular clusters (GC), was obtained from a combination of photometric (e.g., colors, magnitudes) and morphometric (e.g., concentration index, elongation, effective radius) selection criteria, also taking as reference the properties of sources with well-defined classifications from spectroscopic or high-resolution imaging data. Results: Using the FDS catalogs, we present a preliminary analysis of GC distributions in the Fornax area. The study confirms and extends further previous results that were limited to a smaller survey area. We observed the inter-galactic population of GCs, a population of mainly blue GCs centered on NGC 1399, extending over ∼0.9 Mpc, with an ellipticity ϵ ∼ 0.65 and a small tilt in the direction of NGC 1336. Several sub-structures extend over ∼0.5 Mpc along various directions. Two of these structures do not cross any bright galaxy; one of them appears to be connected to NGC 1404, a bright galaxy close to the cluster core and particularly poor in GCs. Using the gri catalogs, we analyze the GC distribution over the extended FDS area and do not find any obvious GC sub-structure bridging the two brightest cluster galaxies, namely, NGC 1316 and NGC 1399. Although NGC 1316 is more than twice as bright of NGC 1399 in optical bands, using gri data, we estimate a GC population that is richer by a factor of ∼3−4 around NGC 1399, as compared to NGC 1316, out to galactocentric distances of ∼40’ or ∼230 kpc