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  2. Limiting magnitude - Wikipedia

    en.wikipedia.org/wiki/Limiting_magnitude

    The limiting magnitude for naked eye visibility refers to the faintest stars that can be seen with the unaided eye near the zenith on clear moonless nights. The quantity is most often used as an overall indicator of sky brightness, in that light polluted and humid areas generally have brighter limiting magnitudes than remote desert or high altitude areas.

  3. Bortle scale - Wikipedia

    en.wikipedia.org/wiki/Bortle_scale

    through a telescope, the brightest Messier objects are pale ghosts of their true selves; when it is full moon in a dark location the sky appears like this, but with the difference that the sky appears blue; limiting magnitude with 12.5" reflector is 14; 8 City sky 4.1–4.5 <18.00 the sky is light gray or orange – one can easily read

  4. List of astronomical interferometers at visible and infrared ...

    en.wikipedia.org/wiki/List_of_astronomical...

    Columns 2-5 determine the range of targets that can be observed and the range of science which can be done. Higher limiting magnitude means that the array can observe fainter sources. The limiting magnitude is determined by the atmospheric seeing, the diameters of the telescopes and the light lost in the system. A larger range of baselines ...

  5. Apparent magnitude - Wikipedia

    en.wikipedia.org/wiki/Apparent_magnitude

    The brightest stars in the night sky were said to be of first magnitude (m = 1), whereas the faintest were of sixth magnitude (m = 6), which is the limit of human visual perception (without the aid of a telescope). Each grade of magnitude was considered twice the brightness of the following grade (a logarithmic scale), although that ratio was ...

  6. Celestial cartography - Wikipedia

    en.wikipedia.org/wiki/Celestial_cartography

    A determining fact source for drawing star charts is naturally a star table. This is apparent when comparing the imaginative "star maps" of Poeticon Astronomicon – illustrations beside a narrative text from the antiquity – to the star maps of Johann Bayer , based on precise star-position measurements from the Rudolphine Tables by Tycho Brahe .

  7. Magnitude (astronomy) - Wikipedia

    en.wikipedia.org/wiki/Magnitude_(astronomy)

    An illustration of light sources from magnitude 1 to 3.5, in 0.5 increments. In astronomy, magnitude is a measure of the brightness of an object, usually in a defined passband. An imprecise but systematic determination of the magnitude of objects was introduced in ancient times by Hipparchus. Magnitude values do not have a unit.

  8. Millennium Star Atlas - Wikipedia

    en.wikipedia.org/wiki/Millennium_Star_Atlas

    The non-stellar objects in the atlas are identified by type and designation. The chart scale is 100 arcsec/mm, matching that at the focus of an 8-inch f/10 Schmidt-Cassegrain. Star magnitudes are essentially Johnson V. Distance labels are given for stars within 200 light-years of the Sun. Proper motion arrows are given for stars with motions ...

  9. Surface brightness - Wikipedia

    en.wikipedia.org/wiki/Surface_brightness

    The total magnitude of a comet is the combined magnitude of the coma and nucleus. The apparent magnitude of an astronomical object is generally given as an integrated value—if a galaxy is quoted as having a magnitude of 12.5, it means we see the same total amount of light from the galaxy as we would from a star with magnitude 12.5.