Radiosonde thermistor measurement errors are basically caused by an imbalance in the radiative heat exchange between the thermistor and its environment. The Accurate Temperature Measuring (ATM) radiosonde instrument, developed at the Wallops Flight Facility of the Goddard Space Flight Center compensates for the radiative error through the use of three (or more) thermistors having coatings with different emissivity and absorptivity characteristics. When the radiative properties of the thermistors' coatings are accurately known in the relevant spectral regions true ambient temperatures can be reliably estimated. A theoretical method for obtaining the radiative error of a single thermistor is possible, but requires knowledge of cloud cover at all levels, surface (skin) temperature, balloon rise rate, and a number of other parameters not typically available. The ATM radiosonde does not require this information to obtain the thermistor error. Using the ATM for routine observations provides corrected temperature profiles for upper air chart analysis and for validating remote sensor measurements.