Altair IV was an inhabited planet. It was the fourth planet of the Altair planetary system. The Altair system was located in the Alpha Quadrant. This was one of three inhabited planets in this system; the others were Altair III and Altair VI. (TOS: "Wolf in the Fold"; Star Trek VI: The Undiscovered Country, production art; TNG: "Encounter at Farpoint")
In the mid-24th century, on stardate 40001.1, Lieutenant Darien Wallace was born on Altair IV. This lieutenant's personnel file appeared in a hallucination of Deanna Troi's. (TNG: "Eye of the Beholder", display graphic)
In 2371, a resident of this world, one Doctor Henri Roget of the Central Hospital of Altair IV, was awarded the prestigious Carrington Award for his work in the field of medicine. (DS9: "Prophet Motive")
Altair IV was also the name of the alien world featured in the film Forbidden Planet.
"The Explored Galaxy" was a map of charted space in the Alpha Quadrant. The Altair system, represented by Altair VI, was located between the Tholian Assembly and Romulus. Both locations were identified in DS9: "The Search, Part II", "Call to Arms" as being located in the Alpha Quadrant.This chart was also seen in several Star Trek: The Next Generation and Star Trek: Deep Space Nine episodes set in the 24th century, from the year 2364 to 2370. These were TNG: "Conspiracy", "The Measure Of A Man", "The Emissary", "The Mind's Eye", "The Game", and DS9: "In the Hands of the Prophets", "Cardassians".
According to the Star Trek: Star Charts (page 44) and on the chart "United Federation of Planets I", the Altair system was located in the Alpha Quadrant. This system, also known as Alpha Aquilae, was a single star system. Primary was a Class A star with a magnitude of +3, which was ten times brighter than Sol. Altair IV was listed as a member planet of the Federation in 2378.