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Paper: The LOFAR Global Sky Model: Some Design Challenges
Volume: 314, Astronomical Data Analysis Software and Systems XIII
Page: 18
Authors: Smirnov, O.M.; Noordam, J.E.
Abstract: 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 catalogs. 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).

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