SGP/SIRS/E21 - Failed Tracker

During the time ranges specified the SIRS solar tracker had failed for unspecified 
reasons.  Measurements of short_direct_normal (NIP) and down_short_diffuse_hemisp (8-48) will be 
incorrect and not recoverable.  Longwave data are unaffected.

• Instantaneous direct normal shortwave irradiance, pyrheliometer thermopile
  voltage(inst_direct_normal)
• Instantaneous uncorrected downwelling shortwave diffuse, shaded pyranometer
  thermopile voltage(inst_diffuse)

• Downwelling shortwave diffuse hemispheric irradiance, pyranometer, maxima(down_short_diffuse_hemisp_max)
• Shortwave direct normal irradiance, pyrheliometer(short_direct_normal)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)
• Shortwave Direct Normal Irradiance, Pyrgeometer, Standard Deviation(short_direct_normal_std)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Pyrgeometer, Minima(down_short_diffuse_hemisp_min)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Pyranometer, Standard
  Deviation(down_short_diffuse_hemisp_std)
• Shortwave direct normal irradiance, pyrheliometer, minima(short_direct_normal_min)