A single 30 min high-resolution spectrum of the optical counterpart to the black hole candidate XTE J1817-330 (ATEL #714, #733) was acquired with the MIKE echelle spectrograph on the Magellan-Clay telescope at Las Campanas Observatory on Feb 20 2006 08:36 UT. In the blue (red), MIKE covered the wavelength range 3530-5070 (4830-9420) Angstrom with a

Recently, the Galactic center has been reported to be a source of very high energy (VHE) γ-rays by the CANGAROO, VERITAS, and HESS experiments. The energy spectra as measured by these experiments show substantial differences. In this Letter we present MAGIC observations of the Galactic center, resulting in the detection of a differential γ-ray flux

We present 64 photoelectric minima observations of 31 eclipsing binaries. We also report three new times of maxima of three SXPHE type pulsating stars.

We present the results of our long-term monitoring of BD +53°2790, the optical counterpart to the X-ray source 4U 2206+54. Unlike previous studies that classify the source as a Be/X-ray binary, we find that its optical and infrared properties differ from those of typical Be stars: the variability of the V/R ratio is not cyclical; there are

Each HDF image consists of a 2.5x2.5arcmin2 Wide Field Pla Camera 2 (WFPC2) pointing. The images were acquired through the broad-band F300W, F450W, F606W and F814W filters. For the present work we have used the publicly available reduced F606W and F814W Version 2 drizzled images with a sampling of 0.04arcsec/pix and a total exposure time of 109050s

The notion that gravitation might lead to a breakdown of standard space-time structure at small distances, and that this might affect the propagation of ordinary particles has led to a program to search for violations of Lorentz invariance as a probe of quantum gravity. Initially it was expected that observable macroscopic effects caused by