We present optical and infrared observations of the soft X-ray transient (SXT) XTEJ2012+381 and identify the optical counterpart with a faint red star heavily blended with a brighter foreground star. The fainter star is coincident with the radio counterpart and appears to show weak Hα emission and to have faded between observations. The RXTE/ASM lightcurve of XTE J2012+381 is unusual for an SXT...

We have produced radio maps, using the ATCA, of the central regions of six southern Seyfert 2 galaxies (NGC 1365, 4945, 6221, 6810, 7582, and Circinus) with circumnuclear star formation, to estimate the relative contribution of star formation activity compared to activity from the active galactic nucleus (AGN). The radio morphologies range from extended diffuse structures to compact nuclear emi...

We present Be star candidates in the open cluster NGC663, identified by Hα imaging photometry with the Palomar Transient Factory Survey, as a pilot program to investigate how the Be star phenomena, the emission spectra, extended circumstellar envelopes, and fast rotation, correlate with massive stellar evolution. Stellar membership of the candidates was verified by 2MASS magnitudes and colors, ...

| The star-connected cycles (SCC) graph was recently proposed as an alternative to the cube-connected cycles (CCC) graph, using a star graph to connect cycles of nodes rather than a hypercube. This paper presents an analysis of broadcasting algorithms for SIMD and MIMD SCCs, covering both one-port and multiple-port versions. We show that O(n log n) one-port broadcasting algorithms that have bee...

Efficiency and reliability are key issues when a star sensor operates in tracking mode. In the case of high attitude dynamics, the performance of existing attitude tracking algorithms degenerates rapidly. In this paper an extended Kalman filtering-based attitude tracking algorithm is presented. The star sensor is modeled as a nonlinear stochastic system with the state estimate providing the thr...

If R is a ring with involution, and a† is the Moore-Penrose inverse of a ∈ R, then the element a is called: EP, if aa† = a†a; partial isometry, if a∗ = a†; star-dagger, if a∗a† = a†a∗. In this paper, characterizations of partial isometries, EP elements and star-dagger elements in rings with involution are given. Thus, some well-known results are extended to more general settings.

For the first time, the abundances of a large sample of subgiant and turn-off region stars in ω Centauri have been measured, the data base being medium resolution spectroscopy from FORS2 at the VLT. Absolute iron abundances were derived for ∼400 member stars from newly defined line indices with an accuracy of ±0.15 dex. The abundances range between −2.2 <[Fe/H]< −0.7 dex, resembling the large m...

We present a detailed reconstruction of the star-formation history of the Constellation III region in the Large Magellanic Cloud, to constrain the formation mechanism of this enigmatic feature. Star formation in Constellation III seems to have taken place during two distinct epochs: there is the 8-15 Myr epoch that had previously been recognized, but we also see strong evidence for a separate “...

In this paper our focus is to study certain covering properties in topological spaces by using semi-open covers. A part of this article deals with Rothberger-type covering properties. The notions of s-Rothberger, almost s-Rothberger, star s-Rothberger, almost star s-Rothberger, strongly star s-Rothberger spaces are defined and corresponding properties are investigated.