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 . ... 22.4 . ... An average sky brightness of V=22.9 mag arcsec -2 is assumed. ... Values for other filters or sky brightnesses can be computed from Table 6.2 , Table 6.1 , Table 6.3 , and Equation 6.2. ...

... region (region-6.2.2) [xmmsas_20030110_1802-5.4.1] . ... The region task will automatically determine the optimal source and background extraction regions for a detected source in an XMM observation. ... The regions are defined in sky coordinates. region will attempt to maximise the area of the extraction region for each source, whilst ensuring that the extraction regions of neighbouring sources do not overlap, and that the background extraction region for a given source excludes neighbouring...

Pulkovo NEO Page . ... Instrumentation and Observations . ... This Windows application serves for determination of spherical coordinates and magnitudes of the objects. ... The objects coordinates are referred to the system of chosen star catalog. ... 2. choice of reference stars with mouse, . 3. measurement of rectangular frame coordinates of objects and reference stars taking account of predefined background parameters, . 4. calculation of the spherical coordinates of objects. ...

Subject of Celestial Mechanics. ... Differential Absolute Coordinates Equations of the Problem. ... General Integral of Non-Perturbed Motion. ... General Equation of Non-Perturbed Orbit. ... Other Integration Methods of Non-Perturbed Motion Differential Equations; Bine Equation for Case of Non-Perturbed Motion. ... Ellipsical Motion, Kepler Equation. ... Motion Differential Equations in Absolute Coordinates. ... Equation of System of Bodies Motion in Barycentric Coordinates, in Relative Coordinates. ...

... 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. ...

... Up: Data Analysis and Processing Techniques . ... Also, a method for quality control of CCD observations is suggested. ... Everyone who observes a celestial object using a CCD detects moving celestial objects as a ``by product''. ... We hope that our investigations may be useful for near-Earth space control and also for searches of the moving celestial objects through analysis of old and new CCD frames obtained at any amateur or professional astronomical observatory. ...

... The J, H and K bands are characterized by a bright background, such a background is mainly due to the emission of atmospheric lines and of thermal radiation. ... If the source cover a large fraction of the slit, spectra off-source must be observed to adequately sample the sky background. ... The on chip integration time (time spent in each position of the slit) must not exceed 40 seconds in J and H bands and 60 seconds in K band. ... We suggest a sequence of 10 for each elementary integration time. ...

... In most astronomical observations the image intensity consists of contributions from both object and sky background. Depending on the complexity of the field and the type of object, different methods are used to estimate and subtract the background intensity. ... Non--linear filters are often used to remove stellar images and other sharp features (see Section ) while extended objects are very difficult to eliminate automatically. ...

The FITS "World Coordinate System" (WCS) standard defines keywords and usage that provide for the description of astronomical coordinate systems in a FITS image header. ... I: "Representations of world coordinates in FITS" , Greisen, E.W. & Calabretta, M.R. (2002), Astronomy & Astrophysics , 395 , 1061-1075. ... This diagram illustrating Bonne's projection with conformal latitude +35 was produced by WCSLIB , a C implementation of the coordinate transformations defined in the FITS WCS papers. ...

... Copyrightї1997 Bob Yen (byen@ix.netcom.com) (http://www.comet-track.com/hb/hb.html) . ... Information on Comet Hale-Bopp for the Non-Astronomer Hale-Bopp rotates about twice a day (3/14/97) . ... The Comet Observation Home Page was been selected to receive the Griffith Observatory Star Award for the week of February 2 - 8, 1997 for excellence in promoting astronomy to the public through the World Wide Web. ... Typically, about 1,000 individual users/computers access this page every day. ...

... For a pulsar search observation, with the two polarizations averaged, a useful rule of thumb can be given for calculating the expected rms noise. If the rms noise, , is expressed in terms of the flux density of the target pulsar, then; . ... Robert Minchin 2012-02-22 ...

... The experience of determination of the link between radio sources and dynamical reference frames is presented. To obtain this connection we used a series of very long baseline interferometry (VLBI) observations of the spacecraft Phobos-2 and angularly nearby quasars. ... The dynamical reference frame is determined by equator and equinox of these ephemerides. ... References . ... The relative orientation of the radio and dynamical reference frames can be described by a sequence of three rotations . ...