The photon torpedo is a powerful, long-range weapon that has been in use aboard Federation starships for over one hundred and fifty years. The weapon comprises an elongated elliptical body some 210cm long and 76cm x 45cm across. The warhead consists of a maximum of 1.5kg of antimatter and 1.5kg of matter. These are divided into many thousands of small pellets suspended in a magnetic field. Included in the torpedo are target acquisition, guidance, detonation assemblies and a warp sustainer unit. If launched during warp flight the torpedo will continue at warp until the sustainer is exhausted. Torpedo range can be extended although this causes a corresponding loss of warhead yield. The photon torpedo can be set to fly a ballistic trajectory, be steered by the launch vessel, or can home in via its own guidance systems. Recent advances in Federation weapons technology have allowed the standard photon torpedo to be upgraded with sophisticated targeting systems and sensor packages, giving them the ability to detect and, if required, target weakened shield areas in the heat of battle.