Orateur
Description
The Vera C. Rubin Observatory’s LSST requires accurate photometric calibration to meet its science goals, particularly for cosmological measurements using Type Ia supernovae. The Collimated Beam Projector (CBP) has been developed to support this effort. By projecting an array of collimated beams onto the telescope pupil, the CBP enables direct measurements of the telescope’s photometric response and facilitates precise characterization of individual optical components, including filters. In addition to telescope response measurements without a filter, the CBP has proven effective for detailed filter throughput characterization. A critical aspect of this effort is the accurate mapping of filter bandpass edges, which can vary by several nanometers as a function of angle of incidence across the large LSSTCam field of view. We report initial measurements of the instrumental telescope response and of the spatially dependent wavelength shifts for the LSSTCam filters using the CBP. These early results demonstrate the capability of the CBP to deliver the high-precision calibration products required to meet LSST photometric performance goals and establish a foundation for ongoing system throughput monitoring.