... The sky background can contribute significant Poisson noise in broad and medium band filters, and must be taken into account during noise calculations. The actual sky brightness depends on the heliocentric ecliptic coordinates (latitude and longitude) in a manner summarized in Table 6.3 . ... For many targets LOW-SKY will have minimal impact on the observing efficiency. ... Table 6.4 shows approximate sky count rates for the WFC and PC1 for filters with significant sky count rates. ...

... The first EGRET catalog ([ Fichtel et al. 1994b ]) used the galactic diffuse gamma radiation model of Bertsch et al. (1993b). ... For the results presented by Bertsch et al. (1993b), the HI and W radio data were deconvolved by integrating the radio data over a velocity interval determined by the endpoints of each distance interval ( ). ... The Galactic radius limit used in the model has been increased to 30 kpc. ... The CR electron spectrum of Fichtel et al. (1991) was used by Bertsch et al. ...

This diagram shows the six superimposed "layers" of the CSS table model. This diagram illustrates the algorithm for calculating a cell's final background. ... The diagram shows how, looking down on the six rectangles, one may compute the background color of each cell. ... A cell without a background color in the top layer is depicted as a "window" onto the lower layers, which give its final background color. ...

... Next: The PROS Big Up: Software Systems Previous: Data Reduction Software . ... The srcinten task provides PROS users with a tool to compute count rates for point sources in the ROSAT High Resolution Imager (HRI). ... Corrected upper limits are cited at locations where the count rate falls below the source detection threshold. ... Srcinten is a new PROS task that computes and applies the above correction factors to the net counts in a user-specified aperture. ...

Next: AXAF Recipes Up: ROSAT HRI Recipes Previous: Quantum Efficiency Correction (a.k.a. For some observations, a significant amount of data may have been rejected during SASS processing because the background level was higher than the calculated threshold for rejection. ... REJECTED EVENTS . ... The recipe will allow the user to include rejected events in the generation of a new qpoe file and filter on the background level. ... This creates a qpoe file with standard + rejected events. ...

... Galaxies 99 Cosmic background with model of cloudy interstellar medium Yu. ... Figure 1: Averaged spectrum of the cosmic background I f in frequency range 0.25 200 MHz for the Galactic poles. ... First interpretation of the cosmic noise background spectrum at broad band frequency range 0.25 200 MHz with a model of the cloudy interstellar medium ISM is presented here. ... Synthesized background spectra I f for regions of the Galactic poles at the frequency range 0.25 200 MHz is presented in Fig. ...

... SPAIN New calculations of the Galactic contribution to microwave back- ground radiation anisotropies are carried out and a probable Galactic predominance over cosmological signals at large scales is explored for these frequencies When we take into account a frequency-dependent contrast of molecular cloud with respect to the Galactic background of the di use interstellar medium, the anisotropic amplitude produced by Galactic dust is of the same order as that of the data from the observations. ...

... Science Activities > PhD Thesis Topics offered by ESO Faculty Members > Thesis Topic: Foreground emission and Cosmic Microwave background intrinsic anisotropies . ... Since its discovery the Cosmic Microwave Radiation (CMB) has been one of the pillars of modern Cosmology. ... Further development of this work is the application of already tested algorithms to disentangle the foreground emission from the CMB maps and the determination of the CMB intrinsic emission. ... Return to list of thesis topics ...

Next: ZODIACAL Up: DIFFUSEGALA Previous: Generation from Ground Calibration Contents . It is not expected to update these CCF files on the short term, neither is there a dedicated calibration activity. However on the longterm it will be possible to estimate the diffuse background components (DGL and Zodiacal light). ... The two background components can be disentangled in this 5-dimensional data-space. Michael Smith 2011-09-20 ...

T he Siding Spring Survey (SSS) is a Near-Earth Object search program that utilises the 0.5-m Uppsala Schmidt Telescope at Siding Spring Observatory, N.S.W., Australia. ... The mission of the Siding Spring Survey is to contribute to the inventory of near-earth objects (NEOs), or more specifically, the potentially hazardous asteroids (PHAs) and comets (PHOs) that may pose a threat of impact and thus harm to civilization. ... Based on the CSS Mission page . ... Siding Spring Survey Main Page . ...

... Method A simple radiative transfer model representing a HISA cloud with fore­ ground and background H i emission and background continuum emission is described by the expression T ON - T OFF =  T S - T C - p T OFF   1 - e -#  , (1) where T ON and T OFF are observed brightnesses on and o# the HISA feature, T S is the spin or excitation temperature of the HISA gas, # is its optical depth, T C is the continuum intensity, and p is the fraction of H i emission lying behind the HISA feature. ...

... 6.02.2002 . ... Credit: A. Kashlinsky ( SSAI ) S. Odenwald ( Raytheon ), 2MASS , NSF , NASA Explanation: What cosmic wallpaper is on the sky? ... Recently, however, the background in near infrared light was imaged at high resolution by the 2MASS telescope , and confirmed earlier estimates that it is over twice as bright as originally expected. ... Visible is light emitted from the very first stars and galaxies in the universe , emitted when the universe was less than half its current age. ...

... BOX= Area which needs to be flat fielded [whole map] OUTSET= Output Set/Subset(s) ORDER= Order of polynomial to be fitted to the map [1] highest allowed order is 21 ** RANGE= Give range of levels to include in fit: [all levels] Input consists of two values. ... Examples for the use of the RANGE= keyword: RANGE=2, 5 (IF 2<value<5 THEN include in fit ELSE value==>blank) RANGE=5, 2 (IF 2<value<5 THEN value==>blank ELSE include in fit) At the RANGE= keyword, the values -INF and INF can be input also. ...

Milky Way X-ray background emission « »: , . ... RXTE , . ... Using near-infrared Galaxy intensity measured with COBE/DIRBE experiment and X-ray data from RXTE and INTEGRAL it was shown that X-ray brightness of the Galactic background emission closely follows its stellar density and can be explained by a cumulative emission of a large number of weak Galactic X-ray sources. ... Map of Galactic background emission in hard X-ray energy band obtained with INTEGRAL observatory. ... 2006, &, 452, 169 ., ...

. Cosmology . Very Early Universe . Cosmic Microwave Background Anisotropy . Dark Matter Models . Large Scale Structure . High Energy Astrophysics . Active Galactic Nuclei . Astrophysics of Compact Objects . Accretion Disks . Scientific Staff:

... Fitting the observed dependence includes calculations of the polarization cross-sections averaged over particles orientation and size distribution, their normalization and the comparison of obtained dependencies with Serkowski's curve representing observational data for a chosen star. ... Variations of the polarization factors with wavelength are shown in Fig. 16 for homogeneous spheroidal particles with PF orientation. ... The distinction between prolate and oblate spheroids is also clearly seen. ...

... Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2002 February 6 . The Cosmic Infrared Background . Credit: A. Kashlinsky ( SSAI ) S. Odenwald ( Raytheon ), 2MASS , NSF , NASA . ... Visible is light emitted from the very first stars and galaxies in the universe , emitted when the universe was less than half its current age. ... About APOD | ... NASA Technical Rep.: ...

... 12c. Venus transit (1) . 12d. Venus transit (2) . 12e. Venus transit (3) . ... 1 The 2004 Venus transit . ... Kepler's third law allows one to evaluate the dimensions of the solar system in relative units, e.g. in " astronomical units " (AUs), where 1 AU is the mean Sun-Earth distance. ... Edmond Halley suggested using the transit of Venus across the Sun's disk, when it appears as a dark round spot --or to quote one observer of the 2004 transit, "like a blueberry in front of an orange." ...

Chromospheric line blanketing and the Hydrogen spectrum in M dwarfs C. I. Short J. G. Doyle We present non-LTE calculations of the H I spectrum in a grid of chromospheric models that represents a dM0 star in which the activity level ranges from quiescent to very active. ... We show that the predicted EW of Ly alpha in all models is reduced by as much as a factor of ~4, and that of H alpha in very active (dMe) stars is enhanced by a factor of about two by the inclusion of background line opacity. ...

... Tonight's Sky . ... The Magazine . ... Observing . ... Magazine . ... Gravitational wave search provides insights into galaxy evolution and mergers . ... The double star 54 Leonis, spiral galaxy NGC 3198, and emission nebula NGC 3199 . ... Open cluster NGC 2818, spiral galaxy NGC 2964, and spiral galaxy NGC 2976 . ... Astronomy for Kids . ... Cosmic Adventures . ... cosmic microwave background . ... Receive news, sky-event information, observing tips, and more from Astronomy's weekly email...