NSA/GNDRAD/C1 - IRT removed for testing

The IRT instrument was at PNNL for cold temperature modifications and testing. Instruments 
returned for the summer season. Data collected after the instrument return looks 
reasonable. 

IRT data recorded during the period the instrument was removed is bad.

• IRT1 mean(irt1_mean)
• IRT1 maximum(irt1_max)
• IRT1 standard deviation(irt1_sd)
• IRT1 minimum(irt1_min)