[en] The Gamma Ray Large Area Space Telescope (GLAST) is a high energy astronomy mission planned for launch in 2005. GLAST features two instruments; the Large Area Telescope (LAT) operating from 20 MeV-300 GeV and the Gamma-ray Burst Monitor (GBM) operating from 10 keV-25 MeV. GLAST observations will contribute to our understanding of active galactic nuclei and their jets, gamma-ray bursts, extragalactic and galactic diffuse emissions, dark matter, supernova remnants, pulsars, and the unidentified high energy gamma-ray sources. The LAT sensitivity is 4x10^-9 photons cm-2 s-1 (>100 MeV) for a one year all-sky survey, which is a factor of >20 better than CGRO/EGRET. GLAST spectral observations of gamma-ray bursts cover over 6 orders of magnitude in energy thanks to the context observations of the GBM. The upper end of the LAT energy range merges with the low energy end of ground-based observatories to provide a remarkable new perspective on particle acceleration in the Universe

[en] Since its launch on 20 November 2004, the Swift mission is detecting ∼100 gamma-ray bursts (GRBs) each year, and immediately (within ∼90 s) starting X-ray and UV/optical observations of the afterglow. It has already collected an impressive database including prompt emission to higher sensitivities than BATSE, uniform monitoring of afterglows, and rapid follow-up by other observatories notified through the GCN. The detection of X-ray afterglows have been found to have complex temporal shapes including tails emission from the prompt phase and bright flares. X-ray afterglows from short bursts has led to accurate localizations. It is found that they can occur in non-star forming galaxies or regions, whereas long GRBs are strongly concentrated within star forming regions. This is consistent with the NS merger model. Swift has greatly increased the redshift range of GRB detection. The highest redshift GRBs, at z∼5-6, are approaching the era of reionization. Ground-based deep optical spectroscopy of high redshift bursts is giving metallicity measurements and other information on the source environment to much greater distance than other techniques. The localization of GRB 060218 to a nearby galaxy, and association with SN 2006aj, added a valuable member to the class of GRBs with detected supernova. The prospects for future progress are excellent give the >10 year orbital lifetime of the Swift satellite

[en] The Compton Gamma Ray Observatory and its four experiment packages continue to function in a nearly flawless manner now well into the sixth year of mission operations. We discuss the status of the mission as of mid-1997, as well as the prospects of an extended mission lasting into the next century

[en] The Compton Gamma Ray Observatory and three of its four experiment packages continue to function in a nearly flawless manner now well into the eighth year of mission operations. Only the EGRET instrument is operating with reduced capability due mainly to the depleted spark-chamber gas, but it is nonetheless still expected to make significant contributions, notably in the area of Solar flares and AGN variability. We discuss the status of the mission as of mid-1999 as well as the prospects of an extended mission lasting well into the first decade of the next century

[en] Since its launch on 20 November 2004, the Swift mission has detected ∼100 gamma-ray bursts (GRBs) each year, and immediately (within ∼90 s) started x-ray and UV/optical observations of the afterglow. It has already collected an impressive database including prompt emission to higher sensitivities than BATSE, uniform monitoring of afterglows and rapid follow-up by other observatories notified through the GCN. The x-ray afterglows have been found to have complex temporal shapes including tail emission from the prompt phase and bright flares. X-ray and optical afterglow detections from short bursts have led to accurate localizations. It is found that short bursts can occur in non-star forming galaxies or regions, whereas long GRBs are strongly concentrated within star forming regions. The location of short bursts in regions of galaxies where late-type stars reside is consistent with the NS merger model. Concerning the connection of GRBs to supernovae, GRB 060218 associated with SN 2006aj adds a valuable member to the class of GRBs with detected supernova. The prospects for future progress are excellent given the >10 years orbital lifetime of the Swift satellite

[en] The last fifty years have witnessed the birth, development, and maturation to full potential of hard X-ray astrophysics. The primary force driving the history of the field has been the development of space-based instrumentation optimized for getting the maximum science out of observations of high-energy photons from astrophysical sources. Hard X-ray telescopes are leading research in areas such as galactic diffuse emission, galactic transients, and active galactic nuclei.

[en] A golden age of GRB astronomy will be upon us when GLAST launches in late 2007 and Swift continues its mission. The Swift NASA MIDEX launched in November 2004 and is detecting ∼100 gamma-ray bursts (GRBs) each year. For almost every burst there is a prompt (within ∼90 s) spacecraft repointing to give X-ray and UV/optical observations of the afterglow. Swift has already collected an impressive database, including prompt emission to higher sensitivities than BATSE, uniform monitoring of afterglows, and rapid follow-up by other observatories notified through the GCN. With the launch of GLAST, there will be the opportunity to combine the powers of Swift and GLAST to make tremendous progress in the study of GRBs. GRBs detected by either mission will trigger observation by the other to give multiwavelength data on prompt and afterglow emission from optical through GeV gamma rays. This paper summarizes scientific results from Swift and CGRO/EGRET and discusses the ways that Swift and GLAST can work together on GRB observations

[en] We are in a very active period in gamma-ray astronomy due primarily to new discoveries from the Compton Gamma Ray Observatory (CGRO). While the near future looks bright with the ESA INTEGRAL mission scheduled for launch in ∼2001, there are currently no major missions being planned beyond INTEGRAL and none being planned at all by NASA. This paper reviews current missions and then looks beyond INTEGRAL to see what mission concepts are being considered. Based on new technologies that are under development such as Si strip detectors for tracking electron-positron pairs in high-energy instruments, CdZnTe strip detectors for fine spatial resolution of hard x-rays, and grazing incidence mirrors with multilayer coatings that work in the 10-100 keV range, several exciting new concepts for future instruments and missions are under study. These include intermediate class high-energy gamma-ray missions (30 MeV-300 GeV) with two order-of-magnitude better point-source sensitivity than the current EGRET instrument on CGRO, intermediate class focusing-optics hard x-ray missions with micro-Crab sensitivities (two order-of-magnitude better than the Rossi X-ray Timing Explorer), MIDEX class hard x-ray (10-200 keV) all-sky survey missions with much better sensitivity and angular resolution than previous surveys, and SMEX and MIDEX class gamma-ray burst missions that can locate bursts to arcsecond accuracies to allow deep counterpart searches at other wavelengths

[en] The Swift Burst Alert Telescope (BAT) is a huge (5200 cm2) coded aperture imager that will detect gamma-ray bursts in real time and provide a location that the Swift satellite uses to slew the optical and x-ray telescopes. This huge size is a challenge for the on-board triggering: trends as small as 1% over af second is equivalent to a 1 σ statistical variation in 1 second. There will be 3 types of triggers, 2 based on rates and one based on images. The first type of trigger is for short time scales (4 msec to 64 msec). These will be traditional triggers (single background) and we check about 25,000 combinations of time-energy-focal plane subregions per second. The second type of trigger will be similar to HETE: fits to multiple background regions to remove trends for time scales between 64 msec and 64 seconds. About 500 combinations will be checked per second. For these rate triggers, false triggers and variable non-GRB sources will be rejected by requiring a new source to be present in an image. The third type of trigger works on longer time scales (minutes), and will be based on routine images that are made of the field of view

[en] We present the first results of Suzaku follow-up of new AGNs detected in the Swift/BAT survey. The Suzaku spectra of Swift J0601.9-8636 and Swift J0138.6-4001 reveal a heavily absorbed power law component with a column density of N_H≅10^23.5-24cm^-2 that dominates above 10 keV, and an intense reflection component with a solid angle > approx 2π from a cold, optically thick medium. We find that these AGNs have an extremely small fraction of scattered light from the nucleus (> approx 0.5%) with respect to the intrinsic power law component. This indicates that they are buried in a very geometrically-thick torus with a small opening angle and/or have unusually small amount of gas responsible for scattering. Our results imply that there must be a significant number of yet unrecognized, very Compton thick AGNs in the local universe, which are difficult to detect even in the currently most sensitive optical or hard X-ray surveys. (author)