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00:01:18 1 History
00:01:35 2 Calculations
00:02:00 2.1 Example: Sun and Moon
00:06:48 2.2 Magnitude addition
00:10:14 2.3 Absolute magnitude
00:12:23 3 Standard reference values
00:15:06 4 Table of notable celestial objects
00:16:28 5 See also
00:20:05 6 References
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Speaking Rate: 0.7853098246194354
Voice name: en-GB-Wavenet-A
"I cannot teach anybody anything, I can only make them think."
- Socrates
SUMMARY
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The apparent magnitude (m) of an astronomical object is a number that is a measure of its brightness as seen by an observer on Earth. The magnitude scale is logarithmic. A difference of 1 in magnitude corresponds to a change in brightness by a factor of 5√100, or about 2.512. The brighter an object appears, the lower its magnitude value (i.e. inverse relation), with the brightest astronomical objects having negative apparent magnitudes: for example Sirius at −1.46.
The measurement of apparent magnitudes or brightnesses of celestial objects is known as photometry. Apparent magnitudes are used to quantify the brightness of sources at ultraviolet, visible, and infrared wavelengths. An apparent magnitude is usually measured in a specific passband corresponding to some photometric system such as the UBV system. In standard astronomical notation, an apparent magnitude in the V ("visual") filter band would be denoted either as mV or often simply as V, as in "mV = 15" or "V = 15" to describe a 15th-magnitude object.
