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February 24, 2005

A zero point calibration was performed on two of the production air temperature sensor units. A 0.00°C water bath was created, in a glass beaker, using de-ionized water and crushed ice (made from de-ionized water).

The beaker was placed on a piece of bubble wrap and some paper towels were wrapped around the side of the beaker to provide insulation.

Both of the units were connected to PC serial ports and the data was read with hyperterminal

The following units were used for this experiment:

          SN 1021 -- new unit built February 2005. 
          SN 1023 -- unit from air temperature #1 location (GBT Level 2) 

The thermistors were submerged in this well mixed bath. After a period of ~30 minutes of settling time, the zero point readings were taken:

          SN 1021 = -0.01°C 
          SN 1023 =  0.02°C 

A "room temperature" point was taken the next morning in a de-ionized water bath. The thermistors were submerged in the well mixed bath. Again, after ~30 minutes of settling time the two room temperature readings were taken:

          SN 1021 = 19.60°C 
          SN 1023 = 19.53°C 

-- JasonRay - 02 Mar 2005