SGP/SIRS/E1 - Tracker failure

The tracker bypassed its limit switches and wound up the tracker instrument cables until 
it stalled and remained frozen.  It was unwound and reset during the site visit on 4/30.

Tracker instruments NIP and 8-48 (short_direct_normal, down_short_diffuse_hemisp) data are 
not recoverable.

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

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