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It includes all stars brighter than magnitude +2.50 in visible light, measured using a V-band filter in the UBV photometric system. Stars in binary systems (or other multiples) are listed by their total or combined brightness if they appear as a single star to the naked eye, or listed separately if they do not.
Other famous Arabic star catalogues include Alfraganus' A compendium of the science of stars (850) which corrected Ptolemy's Almagest; [26] and al-Sufi's Book of Fixed Stars (964) which described observations of the stars, their positions, magnitudes, brightness, and colour, drawings for each constellation, and the first known description of ...
2nd edition – Catalogue of Bright Stars (1940) [10] 3rd edition – Catalogue of Bright Stars (1964) [11] 4th edition – The Bright Star Catalogue (1982) [12] Supplement – A Supplement to the Bright Star Catalogue (1983) [7] 5th edition – The Bright Star Catalogue (1991), [13] which exists only in electronic form, not in book form.
The first list shows a few of the known stars with an estimated luminosity of 1 million L ☉ or greater, including the stars in open cluster, OB association and H II region. The majority of stars thought to be more than 1 million L ☉ are shown, but the list is incomplete. The second list gives some notable stars for the purpose of comparison.
minimum brightness −2.50: planet Earth: seen from Mars maximum brightness −2.48: planet Mercury: seen from Earth maximum brightness at superior conjunction (unlike Venus, Mercury is at its brightest when on the far side of the Sun, the reason being their different phase curves) [42] −2.20: planet Jupiter: seen from Earth mean brightness ...
These stars reside in reflection nebulae and show gradual increases in their luminosity in the order of 6 magnitudes followed by a lengthy phase of constant brightness. They then dim by 2 magnitudes (six times dimmer) or so over a period of many years. V1057 Cygni for example dimmed by 2.5 magnitude (ten times dimmer) during an eleven-year period.
(The S 10 unit is defined as the surface brightness of a star whose V-magnitude is 10 and whose light is smeared over one square degree, or 27.78 mag arcsec −2.) The total sky brightness in zenith is therefore ~220 S 10 or 21.9 mag/arcsec² in the V-band. Note that the contributions from Airglow and Zodiacal light vary with the time of year ...
The brightness of stars appears to fluctuate in a process known as scintillation or twinkling Atmospheric seeing causes the fringes in an astronomical interferometer to move rapidly The distribution of atmospheric seeing through the atmosphere (the C N 2 profile described below) causes the image quality in adaptive optics systems to degrade the ...