Design the station power supply to meet the power demand of the ASPTC-L fan(s). The data acquisition system should have provisions to turn off the ASPTC-L fan(s) if the battery voltage falls below some threshold. Do not turn the fan(s) off at night during normal operation, however, because under clear sky conditions, the ASPTC-L shield emits long-wave radiation and cools to a temperature lower than ambient air temperature. Running the fan(s) ensures that the thermocouple is measuring ambient air temperature, rather than a reduced temperature caused by long-wave radiation cooling.