NASA/GSFC requires specific models of CIMEL CE318-T Sun-Sky-Lunar Spectral Photometers, along with repair, maintenance, and upgrade parts, to support the AERONET program for monitoring aerosol optical properties. The contract will be a sole-source, Firm Fixed Price, Indefinite Delivery/Indefinite Quantity (IDIQ) award to CIMEL ELECTRONIQUE, with a five-year period of performance. No other vendor can meet the government’s instrumentation schedule requirements due to the network’s 30-year standardization on CIMEL equipment. The location for performance of services is not specified. No budget amount is provided.