It could cover a range of -50°C to +220°C. The accuracy was 16°C at a temperature of 50°C and 18°C at 0°C. External temperature gauge no. 3 was mounted at the top of the nose cone and measured the stagnation-point temperature. It covered from -50°C to +450°C with an accuracy of approximately 20°C. The internal temperature gauge was mounted in the high powered transmitter at the base of the instrumentation section. It could cover a range of -60°C to +110°C. The accuracy was 2°C at temperatures from 0°C to +30°C and fell off to an accuracy of 20°C at a temperature of 90°C. External temperature gauges no. 2 and no. 3 transmitted on the low-powered (10 mW, 108.00-MHz) transmitter, and the other two gauges transmitted on the high-powered (60 mW, 108.03-MHz) transmitter. Additionally, the nose cone internal temperature could be indirectly estimated by measuring the frequency of the cosmic ray channel. Calibrations of the oscillator indicate the internal nose cone temperature could be known within 12°C from 0 to +25°C, and to 6°C for 25 to 50°C. Telemetry The telemetry was broadcast continuously. There were no recorders or data storage devices on board, so temperature data could only be received in real time covering periods when Explorer 1 was over a receiving station. There were 5 receiving stations: Patrick Air Force Base (Cape Canaveral), Earthquake Valley (near San Diego), San Gabriel, California, Singapore (Malaya), and Ibadan (Nigeria). All 5 could receive data from the low-power transmitter, only Patrick AFB and San Gabriel could receive from the high-power transmitter. There were typically 4 passes per day over Patrick AFB, Earthquake Valley, and San Gabriel, and 7 passes per day over Nigeria and Singapore. Thermal control The exterior temperature control was achieved by coating a fraction of the stainless steel satellite casing with an aluminum oxide ceramic (Rokide A). Approximately 30% of the nose cone (upper 30 cm of the satellite) and 25% of the upper of the cylindrical body were coated in longitudinal stripes. There was insulation between the nose cone and instrument compartment, and between the instrument compartment and rocket motor section. An internal temperature range of -5°C to +45°C was required for proper operation of the equipment in the satellite. The batteries would not operate below -5°C, but low temperatures would not damage the batteries or equipment. Permanent damage to the equipment would not occur unless the temperature rose