The authors have worked in the past year on integration, characterization, and calibration of The Johns Hopkins University Applied Physics Laboratory's (JHU/APL's) Infrared Seeker Space Calibration and Test facility, a cryogenic-vacuum chamber designed to test infrared seekers that detect targets against low-radiance backgrounds. The facility includes target-like infrared sources with well-known and controllable radiometric attributes and well-known and
controllable size, position, and motion. This paper summarizes the basic facility design, capabilities, concept of operations, current and projected uses, challenges, and lessons learned. It describes the chamber calibration and characterization activities conducted jointly by JHU/APL and the National Institute of Standards and Technology (NIST). In particular, this includes a description of the calibration and characterization methodology, modeling of the chamber optical path from the chamber target source module to the unit-under-test entrance aperture, ongoing calibration of the target source module at NIST with an absolute cryogenic radiometer, and planned end-to-end calibration of the chamber at JHU/APL using NIST's transfer radiometer and JHU/APL's field spectroradiometer.