Algeron IV was the fourth planet of the Algeron planetary system. In 2364, this planet was the destination for the next mission assignment of the USS Enterprise-D after a brief layover at Relva VII. (TNG: "Coming of Age")
According to the Star Trek: Star Charts (pgs. 61, 66), the Algeron system was a single star system. Algeron was an A class star with a magnitude of +5, which was the same brightness as Sol. In the mid-22nd century, Algeron was located in or near Romulan space. After 2160, Algeron was located in or near the Romulan Neutral Zone.
According to the StarTrek.com web site, Algeron IV might have been located in proximity to the Romulan Neutral Zone and was the namesake for the Treaty of Algeron. [1]