In response to the detection of the X-ray source Swift J0732.5-1331 (ATEL #697, #735, #757, #760), we observed its optical counterpart with the Mt. Hopkins 1.5m telescope equipped with the FAST spectrograph. A total of 22 spectra covering 3480-7410 A were acquired between Jan 22 and Mar 1. A 3" slit provided 6 A FWHM resolution. In addition, on

We present the optical identification and characterization of counterparts of four objects previously cataloged as ultraluminous X-ray (ULX) sources. The objects were selected from the E. Colbert & A. Ptak catalog. The optical counterparts are identified as pointlike objects with magnitudes in the range of ~17-19. The optical spectra of three of

We report optical and near-infrared (NIR) observations of the field containing the neutron star X-ray transient XTE J1739-285 (IAUC #7300, ATel #622). The recently reported Chandra localization (ATel #777) provides a significant improvement over the Swift XRT position reported in ATel #602, facilitating the identification of potential counterparts

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The MAGIC Cerenkov telescope has observed very high energy (VHE) γ-ray emission from the active galactic nucleus 1ES 1959+650 during 6 hr in 2004 September and October. The observations were carried out alternating with observations of the Crab Nebula, whose data were used as a reference source for optimizing γ -ray/hadron separation and for flux

By the time, in 1937, the Swiss astronomer Zwicky measured the velocity dispersion of the Coma cluster of galaxies, astronomers somehow got acquainted with the idea that the universe is filled by some kind of dark matter. After almost a century of investigations, we have learned two things about dark matter, (i) it has to be non-baryonic - that is