derivative of the Navaho's NAA Autonetics Division N-6 inertial navigation system (INS), the N5G, was used in the Hound Dog. A Kollsman Instruments Co. star tracker located in the B-52's pylon was used to correct inertial navigation system orientation errors with celestial observations while the Hound Dog was being carried by the B-52. The INS could also be used to determine the bomber's position after the initial calibration and "leveling" process, which took about 90 minutes. The Hound Dog had a circular error probable (CEP) of , which was acceptable for a weapon equipped with a nuclear warhead. The thermonuclear warhead carried by the Hound Dog was the W28 Class D. The W28 warhead could be preset to yield an explosive power of between 70 kilotons and 1.45 megatons. Detonation of the Hound Dog's W28 warhead could be programmed to occur on impact (ground burst) or air burst at a preset altitude. An air burst would have been used against a large area, soft target. A surface impact would have been used against a hard target such as a missile site or command and control center. The Hound Dog could be launched from the B-52 Stratofortress at high altitudes or low altitudes, but not below in altitude. Initially, three different flight profiles for the Hound Dog were available for selection by the commander and the bombardier of the bomber (though other options were added later): High-altitude attack: The Hound Dog would have flown at a high altitude (up to depending on the amount of jet fuel on board the missile) all the way to the immediate area of its target, then diving to its nuclear warhead's preset detonation altitude. Low-altitude attack: The Hound Dog would have flown at a low altitude – below (air-pressure altitude) to its target where its nuclear warhead would have detonated. In this mode of operation, the Hound Dog had a shortened range of about when this flight profile was used. The missile would not carry out terrain following in this flight profile. No major terrain obstructions could exist at the preset altitude along the missile's flight path. Low-altitude attack: The GAM-77B (later AGM-28B) could fly a low radar altitude, from above the ground. As mentioned above in the GAM-77A model description, this shortened range. However, the improvement of "flying in the weeds", was such that the missile could be flown down in ground clutter (radar)