[A0] The central pixel of the A-telescope carried by BBXRT.
[Accretion column] The magnetically-channeled flow of matter to a neutron star's magnetic pole. The accretion column can be either a thin slab or a tall column depending on whether the infalling matter is decelerated close to the neutron star's surface or in a shock high above the surface, respectively.
[ADC] Accretion disk corona.
[Alfvén radius] The radius at which the pressure due to the pulsar's magnetic field equals the ram pressure of infalling material.
[Alfvén Shell] The Alfvén shell is the hollow shell formed by accreting material as it follows magnetic field lines at the surface of the magnetosphere (see Figure 5.4).
[ASCA] The Advanced Satellite for Cosmology and Astrophysics. This is the fourth Japanese X-ray satellite, launched on February 20, 1993.
[ASM] All Sky Monitor -- a telescope carried by RXTE which provides continuous monitoring of the visible sky in the 2-10 keV band.
[Astro-E] The fifth Japanese X-ray satellite. Due to be launched in the year 2000.
[AXAF] The Advanced X-Ray Astrophysics Facility due to be launched in 1998.
[AXP] Accreting X-ray pulsar.
[B0] The central pixel of the B-telescope carried by BBXRT.
[Barycentric time] Time referred to the solar system's barycenter or center of mass.
[BATSE] The Burst and Transient Explorer. An all-sky monitoring gamma ray telescope carried by CGRO. It can be used to make observations of pulsed sources using earth occultations.
[BBXRT] The Broad-band X-Ray Telescope (see Section 1).
[CCD] Charge-coupled device.
[CGRO] The Compton Gamma Ray Observatory, launched in 1991.
[CSRF] Cyclotron Scattering Resonance Feature (see Section 4.2).
[EXOSAT] The European X-Ray Observatory Satellite (see Section 2). It operated from May 26, 1983 to April 9, 1986.
[Fan beam] A broad radiation emission pattern expected from an accretion column whose height is large compared to its width (see Figure 4.3). In this case the observed intensity will be greatest when the line of sight is perpendicular to the pulsar's magnetic field.
[Ginga] The third Japanese X-ray satellite. It was launched on 5 February 1987 and re-entered the earth's atmosphere on 1 November 1991.
[GSFC] Goddard Space Flight Center.
[GSPC] Gas Scintillation Proportional Counter (see Section 2.1).
[HEXE] High Energy X-ray Experiment -- a phoswich detector in the Kvant 1 module of the Mir space station. It covers the energy band 15-200 keV.
[HMXB] High-mass X-ray binary.
[HXD] The Hard X-ray Detector to be carried by Astro-E.
[JFET] Junction field effect transistor.
[LAC] Large Area Collector -- a proportional counter X-ray telescope
carried by Ginga. The LAC covered the energy range
1-37 keV.
[Light-cylinder radius] The radius at which a test particle would have to move at the speed of light in order to co-rotate with the pulsar.
[Line-driven wind] A stellar wind which is driven by the absorption of UV photons with bound-state atomic transitions.
[LMXB] Low-mass X-ray binary.
[Magnetosphere] The region surrounding the neutron star where the motion of the accreting matter is dominated by the neutron star's magnetic field. The magnetosphere's radius is approximately the Alfvén radius.
[ME] The Medium Energy telescope carried by EXOSAT.
[MOS capacitor] Metal-oxide-semiconductor capacitor -- a capacitor where one electrode (the gate) is metal, the other (the substrate) is a semiconductor, and the dielectric is formed from an oxide layer and a depletion region. The depth of the depletion layer, and hence the capacitance, depend on the gate voltage.
[OSO 8] The Orbiting Solar Observatory-I. It was launched on 21 June 1975 and operated until late September 1978. It carried GSFC's Cosmic X-ray Spectrometer which was used to observe X-ray sources in the 2-60 keV band.
[OSSE] The Oriented Scintillation Spectrometer Experiment -- a gamma ray scintillation telescope carried by CGRO. It covers the energy range 50 keV--10 MeV.
[PCA] Proportional Counter Array -- an X-ray telescope carried by RXTE.
[Pencil beam] A narrow radiation emission pattern expected from an accretion column whose height is small compared to its area. In this case the observed intensity will be greatest when the line of sight is along the pulsar's magnetic field.
[phoswich] Short for phosphor sandwich -- a scintillation detector with a guard scintillator for rejecting charged-particle events.
[Population I] Population I stars have high abundances (> 1%) of elements elements heavier than helium. They are believed to have formed after the interstellar medium was enriched by heavy elements from supernovae. They are thus younger than population II stars and can have large masses.
[Population II] Population II stars are stars with low abundances of elements elements heavier than helium. They are believed to have formed before the interstellar medium was enriched by heavy elements from supernovae. They are thus the oldest stars in the Galaxy. Because heavier stars have shorter lives, population II stars have low masses.
[Propeller effect] The propeller effect refers to the centrifugal barrier encountered by accreting matter which is orbiting more slowly than the magnetosphere. This centrifugal barrier can cause the accreting matter to be ejected.
[QPO] Quasi-periodic oscillation.
[ROSAT] Röntgen Satellite -- a German-U.S.-U.K. X-ray satellite launched on June 1 1990.
[RXTE] The Rossi X-Ray Timing Explorer.
[SAA] The South Atlantic Anomaly -- a region of low geomagnetic rigidity off the east coast of Brazil which has a high charged-particle flux.
[Si(Li) detector] An X-ray detector consisting of a reverse-biased silicon diode in which a depletion layer has been created by drifting in lithium.
[SQUID] Superconducting quantum interference device -- a sensitive magnetometer.
[TTM/COMIS] COded Mask Imaging Spectrometer -- a wide-angle
coded-aperture camera in the Kvant 1
module of the Mir space station. It covers the 20-30 keV energy band
with a spatial resolution of
2$
$.
[UV] Ultraviolet.
[Wolter geometry] A scheme for focussing X-rays with grazing-incidence mirrors. Paraxial X-rays are reflected first by a paraboloidal surface and then by a hyperboloid to form an image.
[XIS] X-ray Imaging Spectrometers. These are telescopes with conical foil mirrors and CCD detectors that will be carried by Astro-E.
[XMM] The X-Ray Multi-Mirror Mission.
[XQC] The X-Ray Quantum Calorimeter -- a sounding rocket payload comprising an array of X-ray microcalorimeters. It was successfully flown in June 1996.
[XRS] The X-Ray Spectrometer. An array of microcalorimeters to be carried by Astro-E.