AAS 197, January 2001
Session 87. Innovations in Teaching Astronomy II
Joint Display, Wednesday, January 10, 2001, 9:30am-7:00pm, Exhibit Hall

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[87.03] Research Experience for Teachers at NRAO - Green Bank: Measuring the Opacity of the Sky at 86 GHz

J. N. Ford (Spencer Middle School), J. A. Braatz (NRAO)

An important factor in making decisions about when to observe at millimeter wavelengths is the opacity of the sky to high frequency radiation. NRAO at Green Bank has developed a tipper to measure the atmospheric opacity at 86 GHz. The tipper uses a rotating mirror which reflects radiation from the blank sky onto a radiometer. By plotting the voltage reading from the radiometer against the angle of inclination and then fitting these points to a curve, we find tau, the opacity.

My RET project was to update the curve-fitting algorithm and compute tau from the archived tipper data. These tau values, along with weather data from the Green Bank site, are used to characterize the site for high-frequency observing and will be used to help predict when favorable observing conditions exist.

My 7th and 8th grade math classes continued this research by receiving data in real time from Green Bank, plotting the voltages vs. the angles of inclination and drawing a best-fit line through the data points. The students estimated the atmospheric opacity by measuring the slope of the line. With the tau values they computed they attempt to answer, "When is it a good time to observe on the GBT at high frequencies?" The students are actively involved in real scientific research while learning how to analyze data.

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