TWP/GNDRAD/C3 - IRT failed

The IRT began to fail on 4/7/2006 and failed completely (apparently due to the internal 
power supply) on 4/27. It was replaced on 5/18.

• Surface infra-red temperature(sfc_ir_temp)
• Surface Infra-Red Temperature, Minima(sfc_ir_temp_min)
• Surface Infra-Red Temperature, Standard Deviation(sfc_ir_temp_std)
• Surface Infra-Red Temperature, Maxima(sfc_ir_temp_max)