White paper on science operations

Major changes are taking place in the way astronomy gets done. There are continuing advances in observational capabilities across the frequency spectrum, involving both ground-based and space-based facilities. There is also very rapid evolution of relevant computing and data management technologies. However, although the new technologies are filtering in to the astronomy community, and astronomers are looking at their computing needs in new ways, there is little coordination or coherent policy. Furthermore, although there is great awareness of the evolving technologies in the arena of operations, much of the existing operations infrastructure is ill-suited to take advantage of them. Astronomy, especially space astronomy, has often been at the cutting edge of computer use in data reduction and image analysis, but has been somewhat removed from advanced applications in operations, which have tended to be implemented by industry rather than by the end-user scientists. The purpose of this paper is threefold. First, we briefly review the background and general status of astronomy-related computing. Second, we make recommendations in three areas: data analysis; operations (directed primarily to NASA-related activities); and issues of management and policy, believing that these must be addressed to enable technological progress and to proceed through the next decade. Finally, we recommend specific NASA-related work as part of the Astrotech-21 plans, to enable better science operations in the operations of the Great Observatories and in the lunar outpost era

Einstein observations of active galaxies and quasars

The radio galaxies Centaurus A and Signus B are discussed. In both these sources, a comparison of the radio and imaged X-ray flux is allowed for the measurement of the magnetic fields. Einstein observations of quasars are discussed. The number of known X-ray emitting QSO's was increased from 3 to 22 and the distances where these QSO's were seen to correspond to an age of 15 billion years. It was shown that these quasars contributed significantly to the X-ray background

Canonical correlation analysis of high-dimensional data with very small sample support

This paper is concerned with the analysis of correlation between two high-dimensional data sets when there are only few correlated signal components but the number of samples is very small, possibly much smaller than the dimensions of the data. In such a scenario, a principal component analysis (PCA) rank-reduction preprocessing step is commonly performed before applying canonical correlation analysis (CCA). We present simple, yet very effective approaches to the joint model-order selection of the number of dimensions that should be retained through the PCA step and the number of correlated signals. These approaches are based on reduced-rank versions of the Bartlett-Lawley hypothesis test and the minimum description length information-theoretic criterion. Simulation results show that the techniques perform well for very small sample sizes even in colored noise

Three-dimensional simulations of the orientation and structure of reconnection X-lines

This work employs Hall magnetohydrodynamic (MHD) simulations to study the X-lines formed during the reconnection of magnetic fields with differing strengths and orientations embedded in plasmas of differing densities. Although random initial perturbations trigger the growth of X-lines with many orientations, at late time a few robust X-lines sharing an orientation reasonably consistent with the direction that maximizes the outflow speed, as predicted by Swisdak and Drake [Geophys. Res. Lett., 34, L11106, (2007)], dominate the system. The existence of reconnection in the geometry examined here contradicts the suggestion of Sonnerup [J. Geophys. Res., 79, 1546 (1974)] that reconnection occurs in a plane normal to the equilibrium current. At late time the growth of the X-lines stagnates, leaving them shorter than the simulation domain.Comment: Accepted by Physics of Plasma