The apparent magnitude (m) of a celestial object is a number that is a measure of its brightness as seen by an observer on Earth. The brighter an object appears, the lower its magnitude value (i.e. inverse relation). The Sun, at apparent magnitude of − 27, is the brightest object in the sky. It is adjusted to the value it would have in the absence of the atmosphere. Furthermore, the magnitude scale is logarithmic; a difference of one in magnitude corresponds to a change in brightness by a factor of √ 100, or about 2.512.

Based on this passage, the apparent visual magnitude of a star is a measure of the star's? Let's think fast. Stream of consciousness:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
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The relevant sentence in the passage is: The apparent magnitude (m) of a celestial object is a number that is a measure of its brightness as seen by an observer on Earth. So the final answer is brightness as seen by an observer on Earth.