Moment magnitude scale being constants. For instance, formula_23 depends on rupture speed; it is close to 1 for regular earthquakes but much smaller for slower earthquakes such as tsunami earthquakes and slow earthquakes. Two earthquakes with identical formula_17 but different formula_23 or formula_22 would have radiated different formula_27. Because formula_27 and formula_17 are fundamentally independent properties of an earthquake source, and since formula_27 can now be computed more directly and robustly than in the 1970s, introducing a separate magnitude associated to radiated energy was warranted. Choy and Boatwright defined in 1995 the "energy magnitude" where formula_27 is in J (N·m). Assuming the values
Apparent magnitude 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 "m" or often simply as "V", as in ""m" = 15" or ""V" = 15" to describe a 15th-magnitude object. The scale used to indicate magnitude originates in the Hellenistic practice of dividing stars visible to the naked eye into six "magnitudes". The brightest stars in the night sky were said to be