Talos star group
Talos V was the fifth planet in the Talosian planetary system. The planet had one moon. This system was located within the Talos star group, which was located in the Alpha Quadrant. This planet was located 3.2 astronomical units from the binary stars of Talos A and Talos B. (TOS: "The Cage", "The Menagerie, Part I"; Star Trek VI: The Undiscovered Country, production art)
The planet was never mentioned in dialog; this name came from a map of the Talosian system.
"The Explored Galaxy"
"The Explored Galaxy" was a map of charted space in the Alpha Quadrant. Talos 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 this 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".