Recently, Buta et al. examined the question "Do Bars Drive Spiral Density Waves?", an idea supported by theoretical studies and also from a preliminary observational analysis. They estimated maximum bar strengths Qb , maximum spiral strengths Qs , and maximum m = 2 arm contrasts A 2s for 23 galaxies with deep Anglo-Australian Telescope (AAT) Ks

Using the k-means cluster analysis algorithm, we carry out an unsupervised classification of all galaxy spectra in the seventh and final Sloan Digital Sky Survey data release (SDSS/DR7). Except for the shift to rest-frame wavelengths and the normalization to the g-band flux, no manipulation is applied to the original spectra. The algorithm

A population of small main-belt asteroid pairs (MBAs) residing on very similar heliocentric orbits have been found and studied recently (Vokrouhlicky and Nesvorny, Astron. J. 136: 280 2008 and Astron. J. 137: 111 2009, Pravec and Vokrouhlicky, Icarus 204: 580 2009). These asteroid pairs show some common properties: they are ubiquitous with pairs

We present new results from SEPPCoN, a Survey of Ensemble Physical Properties of Cometary Nuclei. This project is currently surveying 100 Jupiter-family comets (JFCs) to measure the mid-infrared thermal emission and visible reflected sunlight of the nuclei. The scientific goal is to determine the distributions of radius, geometric albedo, thermal

Available from the Minor Planet Center.

Available from the Minor Planet Center.