A monitoring system that includes an infrared detector comprising a field of view that detects temperature data from the field of view and provides a signal indicative of at least a detected temperature of a subject. The system includes a tab comprising a tab temperature that is positioned within the field of view such that the infrared detector detects the tab and emits a signal indicative of a detected temperature of the tab. The system includes a temperature sensor secured to the tab that detects the tab temperature and provides a signal indicative of a reference temperature. A control unit is communicatively coupled to the infrared detector and the temperature sensor and computes a net value between the detected temperature of the subject and the detected temperature of the tab. The control unit calculates a core temperature of the subject by combining the net value with the reference temperature.
