A sentry satellite was a type of artificial satellite used by the Vaadwaur, equipped with sensors for surveillance. One such satellite was placed above the main city on the Vaadwaur homeworld, and survived the near-extinction of the Vaadwaur in 1484.
In 2376, the satellite was still operational and was accessed by Gedrin to provide targeting data to the USS Voyager on the surface, allowing them to launch a photon torpedo strike on a Turei vessel in orbit. After the remaining Vaadwaur attacked Voyager, Gedrin sent data from the satellite to the Turei, so that they could target the Vaadwaur assault fighters in the radioactive atmosphere and the underground chambers where the Vaadwaur had survived in stasis. (VOY: "Dragon's Teeth")