An account in Essonne, France

On Monday, August 10, 2015 between 1 a.m. and 2 a.m., two people observe a colored luminous phenomenon in the sky that intrigues them. One of the two witnesses takes photographs. Only one testimony is collected. The long observation (about 1 hour) of a luminous point moving slowly in the sky suggests a celestial body. It is noted that the star Arcturus was at azimuth 283°, and 13° elevation, that is, exactly in the direction of observation indicated by the witness (intersection N104 / A10 at azimuth 282°, elevation estimated at 15°), therefore fairly close to the horizon; The witness observed the phenomenon on the following days, but sometimes with a different appearance, with fewer colors. On the evening of the first observation, the weather was disturbed with variations in pressure and wind (see the Météociel report). The twinkling of stars is very strong at low elevation, especially if the atmosphere is disturbed (wind, heat), which was the case that evening: one can frequently observe a slow multicolored blinking when observing stars or planets at low elevation with binoculars. The witness does not mention a star in his field of view, whereas he necessarily had to see Arcturus in that direction. The photos do not provide much information due to significant blur and low luminosity. The GEIPAN classifies this case "A": observation of the star Arcturus.