... Near Infrared Camera and Multi-Object Spectrometer Instrument Handbook for Cycle 17 > Appendix B: Flux Units andLine Lists > B.2 Formulae . B.2 Formulae . ... B.2.2 Conversion Between Fluxes and Magnitudes . ... One Jansky (Jy) is defined as 10 ?26 Wm -2 Hz -1 , so it is a unit of measurement of the spectral flux density, F ? ... The spectral flux density F ? ... We list the central wavelengths and zero-point fluxes for the more commonly encountered photometric bands below in Table B.2 . ...

The parameter brief (with its actual uncertainty sbrief) is the mean effective surface brightness in B-band , i.e. the mean surface brightness inside the effective aperture (the circular aperture enclosing one-half the total flux). It is expressed in mag arcsec -2 . ... 2) from the mean surface brightness "LV" inside the effective isophote (elliptical isophote enclosing one half the total flux) measured by Launberts&Valentijn (1989) . ... Effective radius . ... HyperLeda . ...

Two major reasons: the number of stars isn't really seven (it's many more), and they all have different brightnesses, so that you see more or fewer of them depending on viewing conditions. The brightness of stars is measured on the magnitude scale, where the most prominent stars in the sky are around 1st magnitude, and the faintest you can see with your eye are about 6th. ... I think this makes it quite likely that the list will be truncated at Taygeta, giving six visible stars. ...

... SEARCH ASP SITE: Match ALL words Match ANY word . ... ASP Conference Series . ... Accidental Astrophysics: The Devil's In the Magnitudes, Part II . ... The star second to the Sun in brilliance is Sirius. ... Recall the magnitude system, passed down to us through a hundred generations of sky watchers, as a means of quantifying stellar brightness ("Accidental Astrophysics," May/June, p. 9). ... Yes, it is a magnitude difference, but that difference is due to the distance between us and the star. ...

... A comparison of the computed and experimental relations F max ( H), as well as comparison of drift scans of point sources across different horizontal cross-sections of the BP with the corresponding computed cross-sections were made. ... The drift scans of the point source 3С84 (H=87 o ) at the wavelength 7.6 cm across the horizontal cross-sections of the BP (black lines) and the computed horizontal cross-sections of the BP corresponding to them (red lines). ...

Estimations of dome seeng by results of optics quality tests with Shack-Hartman wavefront sensor. ... Measurements on AZT-22 Telescope diameter: 1000 mm F/7.7 Effective subaperture: 37.5 mm Exposure time: 100 ms Time between exposures: 5 s Individual image with tilts in X direction AZT-22 tower The spatial spectrum evolution (top) and wind direction in measurements processes . AZT-22. ... ZTSH dome Zeiss-1000 dome The spatial spectrum evolution (up) end wind direction through time. ...

... It lists the coefficients defining the colour transformations, the zero points for the different filters and the aperture radii used in the photometric calibration analysis. ... The AB system zero point of the filter FilterID is stored in the keyword ABM0 FilterID , e.g. the AB zero point of the the U-filter is stored in ABM0U. The flux conversion factor derived from White Dwarfs of the filter FilterID is stored in the keyword FCF FilterID . ... description . ... AB Flux conversion factor of U . ...

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. ...

... Virtually all detectors and telesco pes are sensitive to only a particular range of frequencies or wavelengths. ... Flux per unit wavelength or frequency So in practice, when we measure how much radiation we receive from some object, we usually mean the energy at some particular frequency, not the integral of the energy over all frequencies (which would be the bolometric brightness). ... But imaging data at UV, optical and IR wavelengths often uses a different approach: broad-band imaging. ...

... Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. February 14, 1999 . Dark Sky, Bright Sun . Credit: STS-82 Crew , NASA . Explanation: In low Earth orbit there is not enough atmosphere to diffuse and scatter sunlight, so shadows are black and the sky is dark - even when the Sun shines. ... Tomorrow's picture: La Nina Earth . ... About APOD > . ... NASA Technical Rep.: ...

... 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. ...

To main of Laboratory . The research work and design of optical and optical-electronic devices are carries out by laboratory staff: . ... Lens: . ... In the layout 1 prism systems perform functions of dispersive element, corrector of aberrations, optical reducer. ... Spectral range 200 - 400 nm; . ... Back Forward . ... The main corrector's function are compensation of field aberrations of the main spherical mirror of a telescope (diameter of 600 mm, f'=1200 mm) and increase aperture ratio. ...

... col_hsb_slice_to_rgb_array . Generate a table of RGB values from a slice of HSB space. void col_hsb_slice_to_rgb_array (unsigned long rgb_array[65536], unsigned long red_mask, unsigned long green_mask, unsigned long blue_mask, float min_brightness, float max_brightness, float start_hue, float stop_hue, float saturation) . ... The HSB slice covers a range of hue and brightness at a fixed satutation. ... The valid range is 0.0 to 1.0 . ... The valid range is 0.0 to just under 6.0 . ...

... AstroCC is a coordinate conversion utility for astronomy. It accepts an object designation or the coordinates of an object and calculates coordinates in alternative systems, and at different dates, times, and locations. It also provides lunar and bright planet coordinates to aid in planning observations. ... BJD values may also be retrieved from http://astroutils.astronomy.ohio-state.edu/time/utc2bjd.html which is based on Eastman et al. ... Coordinate data are obtained from SIMBAD. ...

... Data may be optionally rescaled. copyheader copy header keywords from one FITS file to another ( see also FTOOL cphead ). copywcs copy just the World Coordinate System keywords from the header of one FITS image to others. fcolappend append a constant column to a FITS table fitsparsename Prints components of the extended FITS file name. fitspha convert ASCII files to FITS PHA ( See also listhead supplied with FITSIO. modifyheader modifies FITS header. ...

Each point in this graph represents one star in NGC 2808. The vertical axis represents the brightness (as measured through Hubble's near-infrared F814W filter) of the stars (the brightest stars near the top). The horizontal axis represents the colours of the stars, with bluer stars to the left and redder to the right (blue magnitude minus near-infrared magnitude). ...

... Colours of stars and galaxies hold information on intrinsic and extrinsic parameters, such as stellar temperatures and galaxy populations, selective absorption and colour changes due different dust contents and inclination angles of galaxies, as well as galaxy redshifts and evolution. ... The colour magnitude diagram of 65000 galaxies to which all above-mentioned quantities and others contribute can only be explained by comparison with simulations. ... Colours are also of technical help. ...

... 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 ( )...

Microsymposium 38, MS083, 2003 (A4 format) MERCURY: LOCAL VARIATIONS OF THE PHOTOMETRIC RELIEF. ... Because of trajectory and pointing angle constraints the planet could be observed from Mariner 10 only over a small range of phase angles between about 75o and 110o. Therefore the photometric investigations are restricted to measuring the distribution of brightness on the Mercurian disk. ... Raw versions of real-time processing pictures FDS 0000984 and FDS 0000986 were used (images 196 and 202). ...

... It is found that the correlation coefficients between these two parameters calculated separately inside and outside the sunspot formation zone ±30 have cyclic variation and occur in anti-phase. This suggests different mechanisms of formation of the corona in the fields of small, medium, and large scales. ... The relationship between the coronal green line brightness (CGLB) and the magnetic field strength (MFS) has been investigated by constructing the corresponding synoptic maps for the 1977-2001. ...