TCal
As part of the Munnelyn Instrumentation Lab at Texas A&M, I developed a calibration instrument TCal, similar to DeCal. This instrument will be used to characterize relative throughput as a function of wavelength of imaging systems at observatories around the world. This calibration will improve the science return from large scale surveys such as the LSST at the Vera Rubin Observatory, by placing survey follow-up resources on a common photometric baseline, thus reducing the systematic error due to combining observations from multiple telescopes. To characterize a system we use a 2nm wide monochromater based tunable light source to illuminate the target system to be calibrated and our monitor CCD. The monitor CCD is calibrated in the lab using a NIST photodiode. So, the ratio between the signal in the target and monitor is a measurement of throughput of the target system at a given wavelength. By repeating this measurement at different wavelengths ranging from 300-1000 nm we are able to fully characterize the throughput of an instrument + telescope system as a function of wavelength.