Calibrating and Testing EUSO-SPB in Flight using a Laser and LEDs on an Aircraft

The EUSO-SPB (EUSO super pressure balloon) experiment is designed to make observations of fluorescence light from Extreme Energy Cosmic Ray (EECR) Extensive Air Showers (EASs) by looking down on the atmosphere from above. The flight lasted for 13 days with a total of more than 30 hours of observations on dark nights. The balloon was launched on April 24, 2017, from Wanaka New Zealand. A navigation system consists of MATLAB GUI software together with tracker beacon and Ham radio was designed to track the location of tracking the instrument's field of view. This navigation system was tested prior to the flight in Huntsville, Al. An airplane carrying calibrated UV light emitting diodes (LEDs) and a UV laser was planned to fly under the balloon on a moonless night when it is at its float altitude. This under flight was to calibrate EUSO-SPB using these light sources to produce EECR-like signals. The laser pulses were to calibrate the trigger efficiency and track reconstruction accuracy of the experiment. The flashers will to determine the sensitivity of EUSO-SPB to fluorescent light near the maxima of EASs. Unfortunately, the balloon flight had to be terminated before there was an opportunity for the under flight. This paper describes preparations for the under flight including the design of tracking system and the calibration light sources that were to be carried on the airplane.