The National Institute of Standards and Technology (NIST) is seeking sources for an aberration-free imaging spectrograph to support a new single photon spectroradiometer calibration capability. The spectrograph must meet 20 detailed minimum specifications, including compatibility with Hamamatsu’s Orca-Quest 2 camera, zero astigmatism at any wavelength, and a spectral resolution of 0.065 nm or better. This is a combined sources sought notice and notice of intent to award a sole source contract, but NIST may pursue a competitive acquisition if alternative capable sources are identified. No budget amount or performance location is specified in the description. Interested parties should respond by the closing date to help NIST determine its acquisition strategy.