Altair IIIedit this page

From Memory Alpha, the free Star Trek reference

Altair III is the third planet in the Altair system, orbiting the star named Altair.

When the USS Hood visited this system, Lieutenant Commander William T. Riker stopped Captain Robert DeSoto from transporting to the surface of Altair III with an away team, because he deemed the action as too dangerous, inappropriate for a commanding officer. (TNG: "Encounter at Farpoint", "The Pegasus")