| prev toc next |
To cope with the rapidly increasing volume and complexity of data being generated by ESO's public optical/infrared imaging surveys a high-performance, integrated, end-to-end survey software system has been developed. The aim of the survey system is to provide a robust framework to efficiently monitor observations, transform raw data into science-grade survey products, monitor the progress of surveys and release survey data products, thereby enabling a small group to support survey work over long stretches of time. In this presentation the highlights of the system are presented.
The investigation of weak gravitational distortion produced gravitational lensing effects on Gigaparsec scales reveals the amount and the organisation of dark matter large scale structures in the Universe. The amplitude of the weak distortion is probed by the increase of ellipticity of galaxies that generates gravitational lensing on all distant galaxies, along any arbitrary line of sights selected in the sky. The field-to-field fluctuations of galaxy distortion then inform astronomers on the dark matter power spectrum and the cosmological parameters and provide as well an unbiased description of the cosmic scenario of structure formation over the past Giga-years. In this review, I will describe the scientific goals and will focus the challenging aspects regarding data processing and data handling these surveys demand. I will present the most recent results and their cosmological interpretation, and will show what is expected in the next 10 years, in particular with the CFHTLS that the Canadian and French cosmologists are going to carry out with the Megaprime instrument at CFHT.
The advent of wide-area multicolour synoptic sky surveys is leading to data sets unprecedented in size, complexity and data throughput. VO technology offers a way to exploit these to the full but requires changes in design philosophy.
The Palomar-QUEST survey is a major new survey being undertaken by Caltech, Yale, JPL and Indiana University to repeatedly observe 1/3 of the sky (˜ 15000 sq. deg. between -25 ≤ \delta ≤ 25) in eight passbands. Utilising the 48-inch Oschin Schmidt Telescope at the Palomar Observatory with the 112-CCD QUEST camera covering the full 4° x 4° field of view, it will generate ˜ 1Tb of data per month.
In this paper, we review the design of QUEST as a VO resource, a federated data set and employing VO standards.
The LOFAR Global Sky Model (GSM) will be an all-sky database of some 100 million objects, with flux \& polarization measurements in the 20--200 MHz range. The primary function of the GSM is to support LOFAR calibration and data reduction. The GSM is expected to provide a model of all sufficiently bright sources in any given field, having enough detail and precision to calibrate and subtract these sources and yield residual images of the faint background. The GSM is expected to be continuously updated and refined during LOFAR operation in a ``closed loop'' of sorts. The GSM is also a valuable stand-alone data product that can be made compatible with the VO.
The instrumental characteristics of LOFAR pose large challenges to GSM design, some of them unique even in the field of very large catalogues. Besides sheer size, this includes highly complex source models (thus making for a very non-uniform database structure), stringent performance requirements for operational use, the need to update source models operationally, and various data management issues. This paper will focus on some of these challenges, discuss our approaches to dealing with them, and present a prototype GSM being developed for the LOFAR Pilot Selfcal System (PSS).
| prev toc next |