  The Simons Observatory aims to field 70,000 Transition-Edge Sensor (TES)
bolometers to measure the Cosmic Microwave Background. With so many detectors,
rapid but accurate validation of their properties prior to their integration
into telescopes is of particular importance. This paper describes an
exploration of a new method to improve the simultaneous characterization of TES
thermal parameters and bolometer optical efficiencies without significantly
increasing the data collection time. The paper uses a special-purpose data set
comprising current-voltage (IV) curves collected from thousands of TES
bolometers with a variety of different average bath temperatures and different
cold load temperatures. A subset of the bolometers were masked so they received
no optical power. The new method fits data from the bath temperature ramp and
cold load temperature ramps together as one set instead of fitting each
independently. This enables thermal parameter assessment of the unmasked
detectors without performing additional cooldowns of the cryostat, halving the
time necessary to obtain thermal characterization of all detectors.
