Contemporary long wavelength infrared (LWIR) technology offers potential improvements in Ballistic Missile Defense (BMD) systems. The Designating Optical Tracker (DOT) program being developed for the BMD Advanced Technology Center (BMDATC) is the latest sensor in a series of development and flight test programs. A DOT flight consists of an exoatmospheric probe launched from Kwajalein Missile Range (KMR) engaging a reentry vehicle train in the downrange portion of its flight from the Western Test Range (WTR). An essential step in preparing for each flight is calibration of the LWIR sensor sub-system. Basic performance and functional tests are performed by the supplier, Hughes Air-craft Company, and by Boeing during integration and vehicle-level tests. Detailed radio-metric calibration was performed at the McDonnell Douglas Advanced Sensor Evaluation and Test (ASET) facility. Tests were performed to determine the DOT sensor subsystem performance parameters, typical of those required by other LWIR sensors, to investigate sensor/ detector phenomenology, and to evaluate the proposed sensor timeline to be used during the mission. This paper describes the specific sensor parameter under investigation/calibration during each ASET test, the type of data collected, and the results of the data analysis.