... The FOC suffers from various types of background, the most important of which are thermal electrons, Cerenkov radiation from high energy particles, geocoronal emission lines, zodiacal light, and light scattered within HST from the bright Earth or Moon. ... From on-orbit measurements using the f /96 camera, the former background has been found to vary with solar zenith distance (ZD); see Sections 6.4, 6.5, and 7.0 of the FOC Instrument Handbook , version 7.0, for more details. ...

... This task constructs the PPS product OM OSW FITS source timeseries from two rate files (source and background) produced by separate runs of EVSELECT on a tracking-shifted, QE-corrected OM fast-mode event-list. ... The counts measured in the source and `background` regions, together with the PSF function evaluated over the corresponding regions, are used to set up equations which are then solved to yield source and background rates evaluated for the nomimal coincidence-loss region (r=12 pixels). ...

Introduction This catalogue contains mainly the atomic data needed in the astrophysical investigations of low-density plasma. It is a revised and extended version of the "Catalogue of Atomic Data for the Rarefied Astrophysical Plasma" (Golovatyj et al. ... Low-density plasma. ... In the present study we represent only the atomic data for computation of sp ectra of low-density astrophysical plasma (most known kinds of it are gaseous nebulae), their thermal and ionization structure. ...

... Files in red?history) . ... Belts . ... 12a. Inner Belt . ... The artificial radiation belts from the Argus experiment were located in the "slot" between the two belts and their lifetimes of a few weeks underscored the temporary nature of trapping there (especially for electrons produced just above the atmosphere). ... Like surfers riding a wave, trapped electrons and ions rode this shock and within a minute or so created a new radiation belt just outside the inner belt (picture below). ...

... Files in red?history) . ... Belts . ... 12a. Inner Belt . ... The artificial radiation belts from the Argus experiment were located in the "slot" between the two belts and their lifetimes of a few weeks underscored the temporary nature of trapping there (especially for electrons produced just above the atmosphere). ... Like surfers riding a wave, trapped electrons and ions rode this shock and within a minute or so created a new radiation belt just outside the inner belt (picture below). ...

... Armagh Observatory, College Hill, Armagh BT61 9DG, +44 (0)28 3752 2928 . ... We present the numerical simulations for an electron-beam-driven and loss-cone-driven electron cyclotron maser (ECM) with different plasma parameters and different magnetic field strengths for a relatively small region and short time-scale in an attempt to interpret the recent discovered intense radio emission from ultracool dwarfs. ... A wide frequency band should therefore be covered by future radio observations. ...

The above process keeps the # of protons and the # of neutrons in the early Universe constant. ... Remember, a free neutron (one that is not bound in an atomic nucleus) will decay into a proton + electron (+ anti-neutrino) in about 900 seconds. AT t=0.01 seconds, none of the neutrons have decayed. ... During this epoch, the proton-to-neutron ratio is 1.0 . Epoch #2: . ... Now we have 62% protons and 38% neutrons where at 0.01 seconds we had 50% protons and 50% neutrons. ...

BACKGROUND . ... Electron bombarded silicon (EBS) gain makes the CCD interesting for keV electron detection. Ionizing particles absorbed in silicon create electron-hole pairs at the average rate of one per 3.64 eV incident energy. ... The variance in the number of electron-hole pairs created is given by the Fano factor for silicon (.1-.2) times the number of pairs created. When we use a CCD as a detector of ionizing particles, we would like to collect all of the electrons created. ...

... To address the problem of point-source photometry in restored images Lucy (1994) suggested a two-channel photometric restoration method in which the points are represented as functions in one channel and the background, constrained to be smooth by an additional entropy constraint, in the other. ... In the new CPLUCY implementation the stars can be at arbitrary x , y sub-pixel positions but the entropy constraint on the background, used by PLUCY, is retained. ...

Paths of the incident light and light scattered toward the observer for a single particle in an optically thin nebula. The scattering angle theta scat measures the amount by which the light the observer sees has been deflected from its incident path. ...

... In the three intervening decades there have been many observations of this diffuse emission over a wide range of x-ray energies. ... During the 1970's researchers at the University of Wisconsin, lead by Dr. William Kraushaar, used a series of sounding rocket flights to map the diffuse x-ray emission from the sky in several bands. ... University of Wisconsin Sky Survey map of the B-band (0.13-0.188 keV) x-ray intensity. ... University of Wisconsin Sky Survey map of the 2-6 keV band x-ray intensity. ...

... Duchamp | ... Top | Duchamp is a solution to this proble