... 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 ( )...

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• Refining the Guide Star Catalog: Plate Evaluations
• A New PROS Task for Calculating HRI Source Intensities or Upper Limits

ESTIMATIONS OF EFFECTIVE HEIGHT, SIZE AND BRIGHTNESS TEMPERATURE OF SOLAR CYCLOTRON SOURCES A.N. Korzhavin, T.I. Kaltman Sp ecial Astrophysical Observatory of RAS, Saint-Petersburg, Russia arles@mail.ru The mo deling of microwave emission from a sp ot-asso ciated cyclotron source was done to refine the metho d of estimations of effective brightness temp erature, size and height ab ove photosphere in the pro cessing of RATAN-600 observations. ...

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• LEDA data base
• The ROSAT All-Sky Survey Bright Source Catalogue
• LEDA documentation: homogenisation

Smithsonian Astrophysical Observatory Memorandum To : From Date: Re: M. Cappi, Strong Gravity SDT/YB Team, XMS team : M. Garcia April 14, 2010 XMS high/mid/low resolution event rates for bright AGN mrg-2010-02v2 This memo arises out of the concern that the bright AGN that will be used to observed strong gravity effects ­ in particular those for which time-resolved measurements of test particle orbits will be made ­ may generate counting rates in the XMS that are sufficient to overwhelm it. ...

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• The AstroStat Slog effective area

The ESA/ESO Astronomy Exercise Series 2 . The Distance to Messier 100 as Determined by Cepheid Variable Stars . ... The small variations in distance to the individual Cepheid variable stars in the Cloud are negligible compared with the much larger distance to the SMC. ... In this way Cepheid variable stars can be used as one of the 'standard candles' in the Universe that act either as distance indicators themselves or can be used to calibrate (or set the zero point for) other distance indicators. ...

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• ASP: Star Science in the Autumn Sky
• ASP: Monster Comet Promises Big Show
• ASP: Accidental Astrophysics: The Devil's In the Magnitudes, Part II

In the PROJECT we are using the following peculiar . features of RATAN-600 . ... Brightness temperature sensitivity being equal to the antenna temperature sensitivity .. ... Receiver system .. ... Using aperture averaging effect. dual- beam and dual (multi-) frequency filtration, we demonstrated full filtration of the atmosphere noise down to the receiver noise at all scales of acoustics peaks ( Fig.1 , Fig 2 ). ... We select this frequency as the central one in our project. ... Antenna surface . ...

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• di_eks
• may_iss
• The ROSAT Bright Survey: II. Catalogue of all high-galactic latitude RASS

... They worked out that first magnitude was on average 100 times brighter than the 6th magnitude star. ... This formed an equation of apparent magnitude Mv which is: Mv = -2.5 log f + constant were f is the flux of that star f = ( counts/ exposure) The images that we worked on were taken by the Polar Bear Telescope. ... One of these being that it will be combined with standard stars, which will be used to identify the area of stars and to also help identify other stars within the image. ...

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• http://star.arm.ac.uk/~ambn/abstract208.ps
• Armagh Observatory

Measurement of Sky Brightness at the Iranian National Observatory Davoud Afshari1 and Sadollah Nasiri1,2 1Physics Department, Zanjan University, Zanjan 45195-313, Iran; Institute for Advanced studies in Basic Science (IASBS), Zanjan 45195-1159, Iran; Measurement of light pollution 2 Introduction Among 34 candidate sites at the central part of the country, 5 sites namely Garkesh (in Kashan ), Kolahbarfi(in Kashan ), Deynava (in ... One of these is light pollution. ...

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• http://site2010.sai.msu.ru/static/doc/SPotanin_site2010.pdf

... Effective use of large-scale surveys is dictated by the efficiency of detection of the objects of interest. ... It is a stand-alone software package, designed to work with spectral-line FITS cubes and produce source lists and graphical results showing detected objects. ... Figure 2: Example graphical output of Duchamp showing the zeroth moment of each detection, in its appropriate spatial location. ... Innovations in Searching A key aspect of source detection is the application of a threshold. ...

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• The HIPASS Bright Galaxy Survey
• Surface brightness measurements of extended galactic nebulae
• The ``HIPASS Bright Galaxy Catalog'' (version-4)

... References: %observed energy levels: Del Zanna and Mason, 2005, A , 433, 731 %theoretical energy levels (second column): Storey, Del Zanna, Mason, Zeippen, 2005, A , 433, 717 (scattering calculation) %theoretical energies (third column): Del Zanna and Mason, 2005, A , 433, 731 (SUPERSTRUCTURE calculation with term energy correction) %produced as part of the Arcetri/Cambridge/NRL 'CHIANTI' atomic data base collaboration % % Giulio Del Zanna - June 7 2005 . ...

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... Imagine that for every pixel in the color image, you take its luminance value (that's how bright it appears). ... In the end, you will have a histogram which counts how many times each luminance value appears in the image (that histogram can be used to analyze the distribution of the luminance values in the image). ... For the watermark effect, we want to use the same value that we used in the Stretch Contrast step, so that the lightest color will be in fact white (255), and nothing will get clamped...

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• SAI SN RESEARCH GROUP
• APOD: September 2, 1997 - Dark Sky, Bright Sun
• APOD: February 14, 1999 - Dark Sky, Bright Sun

... Since moonshine is really reflected sunlight, the full Moon is on the average slightly brighter in mid-winter, when Earth is closest to the Sun. In addition, the distance of the full Moon also varies, due to the ellipticity ("eccentricity") of the Moon's orbit. On 22 December, 1999, the two effects combined to produce the brightest full Moon of the century. ... This year will be the first full moon to occur on the winter solstice, Dec. 22nd, commonly called the first day of winter. ...

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... Luminosity (L) · · · · A source's luminosity is the power that it emits in radiation. ... NB Astronomers often say `flux' when they mean `flux density' · SI units are Wm-2Hz -1 -26 filter · Also used are Jy 10 Wm-2Hz -1 E= РРРF d dA dt Specific Intensity, Surface Brightness (I) · Specific intensity (or surface brightness) is the power received (or emitted) per unit area per unit frequency per unit solid angle. ч F at surface of a spherical source = I · · Specific intensity is independent of distance...