SGP/BRS/C1 - SW Direct Normal incorrect

Apparent lightning strike in the instrument cluster area resulted in a failed NIP. Data 
are missing or incorrect.  

The SIRS was due for calibration change outs so the US, DS, DD and NIP were replaced. The 
updated program was loaded at approximately 06/14/2011 1739 GMT.

An estimate of direct normal values can be derived using the following formula:

short_direct_normal = (down_short_hemisp - down_short_diffuse_hemisp)/cos(zenith angle)

• Instantaneous direct normal shortwave irradiance, pyrheliometer thermopile
  voltage(inst_direct_normal)

• Shortwave Direct Normal Irradiance, Pyrgeometer, Standard Deviation(short_direct_normal_std)
• Shortwave direct normal irradiance, pyrheliometer, minima(short_direct_normal_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• Shortwave direct normal irradiance, pyrheliometer(short_direct_normal)