SGP/IRT/E12 - Contamination causing high bias

The IRT measured sky temperatures ~20 K higher than other sites. The problem was corrected 
when the IRT mirror and lens were cleaned.

Do not use data

• Sky Infra-Red Temperature Minima(sky_ir_temp_min)
• Sky infrared temperature, standard deviation(sky_ir_temp_std)
• Sky Infra-Red Temperature(sky_ir_temp)
• Sky Infra Red Temperature Maxima(sky_ir_temp_max)