Next: Prior Models Up: Prior Models and the Previous: Bayesian Paradigm . The observed image differs from the true brightness distribution in having been blurred and encountering statistical noise in the recording process. ... Let us describe the noise models. ... This model can be approximated, at least for high brightness values, by the Gaussian distribution . ... The noise model we will use in this paper is Poissonian; see Molina and Ripley (1989) for the use of robust Gaussian noise models. ...

Peremennye Zvezdy", . ... Star Name: . GSC 3710-00312, USNO-A2.0 1425-04252279 . ... Variability type: . ... USNO-A2.0 1425-04252279 is located at the distance of 15?.7 from the X-ray source 1RXS J031707.9+572942, which is larger than the position error of the source (12?), but its hardness ratio HR1 = 0.03 0.29, typical of chromospherically active stars, and its character of variability allow us to assume that the star is related to the X-ray source. ... Eclipsing variability . Sine wave 1 . ...

... Radio emission at around 90 GHz from star-forming galaxies is expected to be strongly dominated by the free-free component due to ionising radiation from massive, short-lived, stars. We present high surface-brightness sensitivity observations at 90 GHz of the nearby star-forming galaxy Messier 66 with resolution of about 9 arcsec (corresponding to a physical scale of about 500 pc) and analyse these observations in combination with archival lower frequency radio and mid-infrared measurements. ...

... In collaborative work with David Garc?a Alvarez (an Observatory PhD student now at Harvard) and John Butler, an extensive study of the RS CVn binary HR1099 was completed leading to two papers; the first on Doppler imaging and the second on flare activity. Spectra for the Doppler imaging were taken at two different sites, Kitt Peak National Observatory (KPNO), Arizona, and Mount Stromlo Observatory (MSO), Australia, during the 1998 MUltiSIte COntinuous Spectroscopic (MUSICOS) campaign. ...

... We have made observations of the Perseus cluster with the Westerbork Telescope at 610 MHz. ... Several newly detected sources are identified with cluster galaxies. ... No evidence is found for the existence of the previously reported ~ 65'x25' cluster halo, 3C 84B. Key words: radio galaxies - clusters - tailed radio sources buoyancy The Perseus Cluster of galaxies is one of the most fascinating systems accessible to extragalactic astronomers. ...

Zero Point and Colour Transformation Zeropoint Definition ffl Throughput is stable (LBB227 25/02/00 r39 vs 25/08/00 r131) ffl Throughput fudged using LBB 227 and BPM16274 measurement ffl Vega observation simulated ffl Simbad literature survey, average brightness / colour : -- m V = 0.03 -- B­V=0.00 -- U­B=0.005 ffl zero points fixed based on simulated Vega observation (cts/sec) -- U, B, V ...

Next: Star Formation Rate and Up: No Title Previous: Calculation of Evolutionary Tracks . To start calculations, we choose the distributions of the initial binary parameters: the mass of the primary ZAMS component, , binary mass ratio, , orbital separation a . ... whereas the mass ratio distribution is not. ... The zero assumption often made is that the mass ratio distribution has a flat shape, that is binaries with a high mass ratio occur as frequently as those with equal masses. ...

... This allows us to create a model image of the sky at each desired timestep. ... -directories contains the following files (the large subdirectories are indicative listings only): ls -lh total 1.4G drwxrwxr-x 2 whi550 at-astro 4.0K 2010-10-21 22:17 Lightcurves / drwxrwxr-x 2 whi550 at-astro 20K 2010-10-25 11:15 ModelSnapshots/ - rw-r --r-- 1 whi550 at-astro 8.3K 2010-10-25 11:26 README - rw-r --r-- 1 whi550 at-astro 127K 2010-10-21 22:27 RefractivePowerSpectrum.pdf - rw-rw-r --...

... 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. ...

... Using a simple 2-D Gaussian Point Spread Function (PSF) on a constant (flat) sky background, I derive a theoretical photometric and astrometric performance model for analytical and digital PSF-fitting stellar photometry. ... The photometric performance is maximized when either the effective background area or the effective-background-level measurement error is minimized. ... An important, but frequently ignored, noise source is the uncertainty of the measurement of the effective background level ( )...

... Minute Values of Geomagnetic Field Components . ... AA 1868 - Present (3 hourly and daily) (monthly) (yearly) (Lists and histograms of geomagnetic disturbance and Solar Sunspots) KP_AP 1932 - Present (3 hourly and daily) (Lists and histograms of geomagnetic disturbance and Solar Sunspots) AE_HV 1957-75, 78-88 (hourly) AE_MIN 1978-881-6;198903;1990-94 (minute) DST 1957 - Present (hourly) PC 1975 - Present (15-minute) AMANAS 1959 - Present (3 hourly and daily) KMKNKS 1983 - Present (3 hourly) . ...

... The hot component shows very spectacular activity: irregular outbursts accompanied by fast, massive outflows and jets. ... Diffraction-limited images for both components of CH Cyg binary system were reconstructed using visible speckle interferometry at BTA 6-m telescope (Fig.1). The orbital period 15.6 years and masses: 2.0 Msun and 0.7 Msun for red giant and white dwarf, respectively were derived from angular distance (0.042") and magnitude difference (2 m ) of the components. ... Fig.1. ...

In this gallery are many images of Low Surface Brightness Galaxies which have recently been discovered and analyzed. ... The central surface brightness of this galaxy is 24.28 . Malin 2 This galaxy is another huge disk galaxy with a scale length of 15 kpc and a redshift of 15000 km/a. The high surface brightness knot in one of its spiral arms actually has the same color, luminosity and H-alpha equivalent width as the entire Large Magellanic Cloud . ... Truly it is a Low Surface Brightness Galaxy. ...

NMW survey overview . Access image archive . ... The New Milky Way survey aims to detect bright (V<13.5) optical transients near the Galactic plane using an automated wide-field (8x6 deg.) system capable of surveying the whole Milky Way area visible from the observing site in one night. ... All images obtained during the transient search survey are available online (please use the image archive access form ). ... Images per field: . ... Images per night: . ... Milky Way imaging time: . ...

Physical and dynamical parameters of particles in outbursting Comet 17 P/Holmes . ... The time depending offset between the center of brightness and center of mass of the comet nucleus has been determined on the ground of positional observations of the comet. ... The motion of these particles allowed subsequent offset between the center of brightness and center of mass of the comet nucleus to be obtained from positional observations. ... comet, dynamical model, outburst, brightness. ...

... SB, Porb = 55.9212d. V0745 Cas| ... Component B of the double system observed brighter than in the Hipparcos Input Catalogue. ... The variability may be due to the fainter component. ... Type ELL: is also possible. pi Cas| ... Variability type and spectral type (F2/F3Ib/II) do not agree. ... Variability type and spectral type (F3/F5II) do not agree. ... Variability may be due to component B. VZ Pic| ... Variability may be due to component B. V1377 Ori| ... SB, Porb = 9.073d. V0421 Cep|105091| ...

Once students get the hang of it, they can find and measure the brightness of Delta Cephei in a few minutes. ... of Delta Cephei . ... Oct. ... The following table lists the measurements of Delta Cephei made by one amateur astronomer in autumn 1990. ... 4.0 . ... This activity is a simplified version of one that appeared in Hands-On Astrophysics, a series of activities prepared by the American Association of Variable Star Observers with support from the National Science Foundation. << previous page | ...

... The earliest X--ray observations were carried out in the mid--1970s. X--ray luminosities of order L erg/sec were detected in the 2-11 keV range in the direction of the Orion star forming region. ... These observations showed that the O and B stars were the brightest X--ray sources, and that TTs were also associated with emission. Feigelson and Kriss (1981) showed that some of the X--ray sources were associated with PMS stars which had not been previously detected which H surveys. ...

... Other Characteristics of the Sun: Variability of Rotation, Magnetism, Chemical Structure, Planetary System. ... Methods of Solar Magnetic Fields Measuring: Visual, Photografic, Photoelectric. ... Empiric Datas of Magnetic Fields in Photosphere, Chromosphere and Corona. ... Characteristics of Magnetic Field in Balanced Force Tubes by Potential and Forceless Field. ... Phenomenons in Active Region (Magnetic Field, Spots, Torches, Solar Prominences, Flares, Discharges. ... Magnetic Fields in Flares. ...

Hubble Observations Shed New Light on Jupiter Collision . Was it a comet or an asteroid? ... Their initial findings, combined with results from other space-borne and ground-based telescopes, shed new light on Jupiter's atmospheric winds, its immense magnetic field, the mysterious dark debris from the impacts, and the composition of the doomed comet itself. ... Hubble's ultraviolet observations show the motion of very fine impact debris particles now suspended high in Jupiter's atmosphere. ...