===== FM =====
=== Focused Moon Observation ===

FM results in an O3 observation to be taken with the moon as the radiation source. The Brewer Zenith Prism and Azimuth Tracker are oriented to the moon, the Iris is opened, FW#1 is rotated to the position 3, and FW#2 is adjusted for maximum intensity, starting at position 2.\\
 
An FM observation consists of five sets of 80 cycles of the slit mask (a measurement), each cycle taking a reading for 2*0.14 seconds on each wavelength. 
Intensity data for six wavelengths, and the dark count, from the five measurements is recorded. The Azimuth and Zenith positions are updated after each measurement. After each measurement O3 is calculated, and after the final measurement all data is processed, resulting in a single summary set for the total observation. \\

An FM measurement takes approximately 15 minutes to complete. Note that FM observations are not valid for ZA>75° and the message ”Waiting for the Moon to Rise above ZA=75” may appear prior to this angle condition being met.