Absolute Magnitude

Magnitude is a measure of the brightness of an object. The scale is logrithmic and the brighter the object the lower the number. Magnitude is usually one of two types Apparent Magnitude (m) and Absolute Magnitude (M). On ancient Terra the stars of the sky were divided into 6 magnitudes, with 1 being the brightest and 6 the faintest with each division being approximately 2 times difference, this was later revised so that a 1^st magnitude star was 100 times brighter than a 6^th magnitude star. First Polaris then Vega were taken to be the 0 point on the scale. So each step is the fifth root of 100 different (2.512).

Magnitude is not limited to the 0-6 scale, most primary stars will be highly negative (Sol from Terra is −26.73). The faintest magnitude visible with a Humaniti eye is 6.5. Binoculars give 9.5, and an 8m ground telescope can resolve to 27.

Apparent Magnitude

a measure of its brightness as seen by an observer on the ground, normalized to the value it would have in the absence of the atmosphere

Absolute Magnitude

the apparent magnitude, an object would have if it were at a standard luminosity distance away from us, in the absence of interstellar extinction

Absolute Magnitude is the apparent magnitude at 10 parsecs. Given the absolute magnitude and the distance to a star, the apparent magnitude can be caclulated by: <math>m = M + 5((\log_{10}D)-1)</math> where D is the distance in Parsecs (must be adjusted for extra galactic objects). Thus Antares at M -5.28 as seen from Capital (distance of ~38 parsecs) would be:
<math>m = -5.28 + 5((\log_{10}38)-1)</math>
<math>m = -5.28 + 5(1.58-1)</math>
<math>m = -5.28 + 5(0.58)</math>
<math>m=-5.28 + 2.9</math>
<math>m=-2.38</math>

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Absolute/Apparent Magnitudes for comparison:

Object	Absoulte Magnitude	Apparent Magnitude (Terra)	Apparent Magnitude (Capital)
Sun	4.83	−26.73	10.38
Moon (full)	n/a	−12.6	n/a
Visible during Daylight	n/a	−3.9	-3.9
Moon (new)	n/a	–2.5	n/a
Sirius Brightest Star	1.42	−1.47	6.97
Canopus 2nd Brightest star	−5.53	-0.7 (-2.04)	(0.73)
Vega 5th Brightest star	0.58	0.03	5.96
Antares 16th Brightest star	−5.28	1.09 (0.83)	-1.35 (-2.38)
Deneb 19th Brightest star	−8.73	1.25 (-2.2)	0.96 (-3.09)
LBV 1806-20	−14.2	8.4	8.4
Quasar 3C 273	−26.7	12.8	12.8

• Note the numbers in () above are for adjusted locations of stars on the maps.

This list of sources was used by the Traveller Wiki Editorial Team and individual contributors to compose this article. Copyrighted material is used under license from Far Future Enterprises or by permission of the author. The page history lists all of the contributions.

• Wikipedia (various)