SGP/SWS/C1 - Spectrometer heater controller failed

A heater controller failed on the Shortwave Spectrometer instrument (SWS). The heater 
maintained the Silicon diode array spectrometer temperature at 27 +/-0.2 Celsius. Operatation 
of the instrument is not dependent on the proper operation of the heater, therefore the 
SWS was run during the 10 day period in which the problem was diagnosed and repaired.  
However, up to a 4 percent error in radiance values can be expected in the wavelength range 
from 900 nm to 981 nm. 

The SWS data spans a wavelength range of 350 nm to 2150 nm with a typical error in 
radiance value of 2 percent.  From our analysis, the data with errors outside of the typical, 
only spans a small portion of the total wavelength range.  An instrument calibration with 
the heater malfunctioning was performed on September 26, 2007, and a response function was 
generated by the SWS mentor. If necessary, data users can contact the mentor to obtain 
the response function which will improve but not eliminate completely the errors in 
absolute spectral radiance values measured.

• Calibrated spectrum(zen_spec_calib)

SGP/SWS/C1 - Instrument offline for annual calibration

SWS instrument was taken offline for an annual calibration.  

Comparision of the December 19, 2007 annual calibration with the previous annual 
calibration done on November 8, 2006 shows very little change in the instrument sensitivity over 
2007.  From our analysis, there is effectively no change in the silicon spectrometer 
sensitivity from 400 to 981 nanometers.  The InGaAs spectrometer shows a slight decrease in 
sensitivity of 1 to 2% over the wavelength range of 982 to 2150 nanometers, which is within 
our expected error range.  Characterization of the change in sensitivity from 350 to 400 
nanometers over the year is a bit more difficult to determine and maybe greater than our 
expected error of 2%.  The science team at the University of Colorado is currently 
working on this problem.

• Output of voltage converter to +12VDC(pc104_pos12v)
• base time(base_time)
• Internal Temperature(internal_temp)
• Output of voltage converter to -12VDC(pc104_neg12v)
• Silicon spectrometer temperature(SI_spect_temp)
• lat(lat)
• Time offset of tweaks from base_time(time_offset)
• lon(lon)
• Indium/Gallium/Arsenic spectrometer temperature(InGaAs_spect_temp)
• Dummy altitude for Zeb(alt)
• time(time)
• Output of voltage converter to +5VDC(pc104_5v)
• Output of voltage regulator at +5VDC(ps2_5v)
• Output of voltage regulator at +12VDC(ps2_12v)

• lon(lon)
• Wavelength(wavelength)
• lat(lat)
• time(time)
• Shutter state (1:closed, 0:open)(shutter_closed)
• Time offset of tweaks from base_time(time_offset)
• Calibrated spectrum(zen_spec_calib)
• Dummy altitude for Zeb(alt)
• base time(base_time)