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Twenty-one 1,000W tungsten-halogen FEL lamps were chosen to become part of the OSPREy lamp library. Nine lamps were calibrated by NIST, while the rest are uncalibrated, but seasoned lamps (by the supplier). These lamps were operated for periods ranging from 4-35 h to assess their stability. Changes in brightness were typically in the range of +/-0.02% per hour with a few lamps exhibiting slightly larger drifts. These lamps should be seasoned for an additional 8-30 h to improve their stability. The calibration laboratory at BSI was upgraded to operate lamps of the OSPREy lamp library at the highest level of accuracy achievable. Upgrades included a new system for powering the lamps, which allows regulation of the lamp current to within a precision of 50 microA (or 0.0006% for a target current of 8.2 A). Other facilities required for accurate lamp transfers were also upgraded to reduce uncertainties caused by stray light, misalignment, and temperature variations. Three radiometers are available for maintaining optical standards: an OXL instrument calibrated at BSI, an OXE instrument currently awaiting results of a NIST SIRCUS calibration (and not used for the results presented in this chapter), and a transfer radiometer based on the BSI ground-based UV (GUV) class of radiometers that is called an XGUV. A comprehensive uncertainty analysis showed the use of moderate-bandwidth radiometers, such as the XGUV and OXL, are suitable to transfer calibrations of FEL lamps. Uncertainties related to the relatively large bandwidth of these instruments are on the order of 0.3%. All NIST lamps were intercompared and agreed to within +/- 2%, which is a very good result considering that some lamps are rather old and were calibrated against different NIST scales. A protocol on the usage of the lamp library was developed with the goal of preserving the spectral irradiance scale over a timescale of 15 years or more.