We report on recent progress with development of astronomical X-ray optics based on bent Si wafers. Recent efforts with Si wafers have been focused on new forming technologies such as method of deposition of thin layers. The role of substrates quality in performance of final mirror arrays, as required by large future space X-ray astronomy experiments was also studied.

We report on the Chandra X-ray Observatory and Hubble Space Telescope observation of two low core density globular clusters, NGC6144 and E3. By comparing the number of X-ray sources inside the half-mass radius to those outside, we found 6 X-ray sources within the half-mass radius of NGC6144, among which 4 are expected to be background sources; 3 X-ray sources are also found within the half-mass...

A high fraction of the Low Mass X-ray Binaries (LMXBs) in early-type galaxies are associated with globular clusters (GCs). Here, we discuss the correlations between LMXBs and GCs in a sample of four early-type galaxies with X-ray source lists determined from Chandra observations. There is some evidence that the fraction of LMXBs associated with globular clusters (fX−GC) increases along the Hubb...

The selection of clusters of galaxies through their X-ray emission has proved to be an extremely powerful technique over the past four decades. The growth of X-ray astronomy has provided the community with a steadily more detailed view of the intracluster medium in clusters. In this review I will assess how far X-ray surveys of clusters have progressed and how far they still have to travel. 1.

The 17 m MAGIC Cherenkov telescope for gamma ray astronomy between 30 and 300 GeV started operations in its final configuration in October 2003 and is currently well into its calibration phase. Here I report on its present status and its first gamma ray source detections.

Since several years pnCCDs are well known as radiation detectors for spectroscopic imaging in many fields of science: X-Ray Fluorescence analysis (XRF), X-ray astronomy, X-ray Free Electron Laser science, synchrotrons and in the visible range as wave front sensors in adaptive optics systems. For direct electron detection in the focal plane of (S)TEMs they have delivered remarkable results in an...

The nature of the unidentified gamma-ray point sources in the galactic plane is a long standing puzzle of gamma-ray astronomy. Kaaret and Cottam (1996) showed that 16 of the 25 unidentified gamma-ray point sources near the galactic plane lie in or near associations of massive stars, likely sites of pulsar formation, and that the intrinsic luminosity distribution of the sources is consistent wit...

We present the X-ray catalog and basic results from our Chandra Large Area Synoptic X-ray Survey (CLASXS) of the Lockman Hole-Northwest field. Our 9 ACIS-I fields cover a contiguous solid angle of ∼ 0.4 deg and reach fluxes of 5×10−16 ergs cm s (0.4−2 keV) and 3×10−15 ergs cm s (2−8 keV). Our survey bridges the gap between ultradeep pencil-beam surveys, such as the Chandra Deep Fields (CDFs), a...

We report on a multiwavelength campaign on the TeV γ-ray blazar Markarian (Mrk) 421 performed during December 2002 and January 2003. These target of opportunity observations were initiated by the detection of X-ray and TeV Department of Physics, Washington University, St. Louis, MO 63130, USA Physics Department, Tanta University, Tanta, Egypt Department of Physics, University of Massachussetts,...

Although gamma ray showers are muon-poor, they still produce a number of muons suucient to make the sources observed by GeV and TeV telescopes observable also in muons. For sources with hard gamma ray spectra there is a relativèenhancement' of muons from gamma ray primaries as compared to that from nucleon primaries. All shower gamma rays above the photo-production threshold contribute to the n...