The Imperial Research Ship was a ship used by the Empire in its experimental TIE starfighter program, presumably involved in the research and development of new designs. The ship's eight hangars undoubtedly held large numbers of experimental designs, though the exact number is unknown.
Though unarmed, the ship was well protected with shields as heavy as a Strike-class medium cruiser and much heavier armor. It had control towers on both the dorsal and ventral sides, each equipped with large communications arrays. The ship had only one main sublight engine, giving it acceleration comparable to a Victory I-class Star Destroyer. Later intelligence revealed that it was manufactured by Sienar Fleet Systems, and though it was not able to escape the Rebel attack it was apparently hyperdrive-capable.
The Rebel Alliance only ever encountered one of these craft, the Sardis, during their successful attempt to destroy the research station Obsidian. The research ship was designated a primary target and gave no apparent defensive fire as a squadron of B-wings led by Ace Azzameen destroyed it and the station, effectively ending the program.