We 1 summarize previous VLBI observations of Sgr A* at millimeter wavelengths and present new results from VLBI observations at 86 GHz and at 215 GHz. At 86 GHz the measured closure phase is close to zero, consistent with a point-like or symmetric structure of 190±30 µas size. At 215 GHz we have (for the first time) detected Sgr A* with a signal-to-noise ratio of 6. This yields a tentative size...

The spectra of the quiescent counterparts to the Soft Gamma-Ray Repeaters SGR 1900+14 and SGR 1806–20 peak in the infrared. Their infrared spectra appear to contain several components: the photospheric emission from star(s) dominates at shorter wavelengths, a bright point source dominates at 25 μm, while an extended source dominates at 60 μm. However, we show here that these counterparts were n...

ROSAT observations found no convincing evidence for X-ray sources located in local dwarf spheroidal galaxies (dSph). Now with more sensitive instruments on board Chandra and XMM-Newton we can reach fainter luminosity levels. We report on an observation of the Sagittarius (Sgr) dSph made using Chandra and an observation of the Carina (Car) dSph made using XMM-Newton. Our observations are sensiti...

We report the first detection of interstellar hydrogen fluoride. Using the Long Wavelength Spectrometer (LWS) of the Infrared Space Observatory (ISO), we have detected the 121.6973 μm J = 2 − 1 line of HF in absorption toward the far-infrared continuum source Sagittarius B2. The detection is statistically significant at the 13σ level. On the basis of our model for the excitation of HF in Sgr B2...

We present evidence for burst emission from SGR 1900+14 with a power-law high-energy spectrum extending beyond 500 keV. Unlike previous detections of high-energy photons during bursts from soft gamma repeaters (SGRs), these emissions are not associated with extraordinarily bright flares. Not only is the emission hard, but the spectra are better fitted by D. Band's gamma-ray burst (GRB) function...

We have obtained infrared spectra of the star suggested to be the counterpart of the soft γ-ray repeater (SGR) 1806−20. We found strong emission lines similar to those seen in the spectra of the rare Luminous Blue Variables and B[e] stars. A He I absorption line is also seen, from which we infer a spectral type O9–B2. This classification, in combination with the minimum distance of ∼ > 6 kpc in...

We discuss the density and radial velocity distributions of over 3000 candidate RR Lyrae stars selected by various methods using Sloan Digital Sky Survey data for about 1000 deg of sky. This is more than 20 times larger sample than previously reported by SDSS (Ivezić et al. 2000), and includes candidate RR Lyrae stars out to the sample limit of 100 kpc. A cutoff in the radial distribution of ha...

We discuss observations of the soft gamma repeater SGR 1806–20 during the RXTE Target of Opportunity observations made in November 1996. During the ∼ 50 ksec RXTE observation, HEXTE (15− 250 keV) detected 17 bursts from the source, with fluxes ranging from 3× 10 to 2.2× 10 ergs cm s (20− 100 keV). We obtained spectra for the brighter HEXTE by fitting thermal bremsstrahlung and power law functio...

The fourth unambiguously identified Soft Gamma Repeater (SGR), SGR 1627–41, was discovered with the BATSE instrument on 1998 June 15 (Kouveliotou et al. 1998). Interplanetary Network (IPN) measurements and BATSE data constrained the location of this new SGR to a 6 segment of a narrow (19) annulus (Hurley et al. 1999a; Woods et al. 1998). We present two bursts from this source observed by the Al...

The discovery of the Sgr dwarf galaxy shows that the Galactic halo contains large clumps which are not full viralized. This may change implications of observed microlensing events towards the LMC. If more than one such systems are hidden in the Galactic halo, then given their enormous angular size, there is a significant chance for any line of sight, say the LMC direction, to intersect one of t...