North-Georgia Educational Radio Telescope (NERT) Gain-Temperature Calibration

Abstract

NERT observations of a calibrated radio noise source are used to determine the receiver gain-temperature corrections necessary for accurate calibration of the output signal voltage. The output voltage of the SpectraCyber receiver at a constant gain is proportional to the radio intensity detected by the radio telescope. In previous observations of the second brightest discrete radio source in the sky, supernova remnant Cassiopeia A, the maximum output signal voltage was only 5 mV above the background. Preliminary determinations of the gain-temperature correlation have shown that an inverse relation exists such that variation of only 0.5^o Fahrenheit could hide this 5 mV detection peak. Calibrating this correlation is critical for accurate, repeatable radio observations of the sky with NERT. Installations of new control and recording software include LabPro for temperature observation and Radio SkyPipe for object observation. SkyPipe has an equation plot function which can be used to calibrate NERT observations as they are recorded, streamlining this data reduction process in the future.