Neptune is not visible to the unaided eye and is the only planet in the Solar System found by mathematical prediction rather than by empirical observation. Unexpected changes in the orbit of Uranus led Alexis Bouvard to deduce that its orbit was subject to gravitational perturbation by an unknown planet. Neptune was subsequently observed with a telescope on 23 September 1846 by Johann Galle within a degree of the position predicted by Urbain Le Verrier. Its largest moon, Triton, was discovered shortly thereafter, though none of the planet's remaining known 14 moons were located telescopically until the 20th century. The planet's distance from Earth gives it a very small apparent size, making it challenging to study with Earth-based telescopes. Neptune was visited by Voyager 2, when it flew by the planet on 25 August 1989. The advent of Hubble Space Telescope and large ground-based telescopes with adaptive optics has recently allowed for additional detailed observations from afar.
When was Neptune first observed?
23 September 1846

The most important source after Polybius is Diodorus Siculus who wrote his Bibliotheca historica between 60 and 30 BCE and reproduced some important earlier sources such as Hieronymus, but his account of the Hellenistic period breaks off after the battle of Ipsus (301). Another important source, Plutarch's (c.50c.120) Parallel Lives though more preoccupied with issues of personal character and morality, outlines the history of important Hellenistic figures. Appian of Alexandria (late first century CE-before 165 CE) wrote a history of the Roman empire that includes information of some Hellenistic kingdoms.
Where was Apprian from?
Alexandria

The lateral cut NAB curve was remarkably similar to the NBC Orthacoustic curve that evolved from practices within the National Broadcasting Company since the mid-1930s. Empirically, and not by any formula, it was learned that the bass end of the audio spectrum below 100 Hz could be boosted somewhat to override system hum and turntable rumble noises. Likewise at the treble end beginning at 1,000 Hz, if audio frequencies were boosted by 16 dB at 10,000 Hz the delicate sibilant sounds of speech and high overtones of musical instruments could survive the noise level of cellulose acetate, lacquer/aluminum, and vinyl disc media. When the record was played back using a complementary inverse curve, signal-to-noise ratio was improved and the programming sounded more lifelike.
How did the NBC Othacoustic curve relate to the NAB curve?
remarkably similar