This sequence was captured with a Raspberry Pi, an 8mp Pi NoIR camera, and a Quantaray R2 filter. The unusual feature is the red flashes that begin occurring between 3 and 4 minutes into the time-lapse video. The evening was clear and I've been wondering what causes the bright red flashes. There is an atmospheric phenomenon called Green Flash that sometimes occurs shortly after sunset. It may be that Red Flash and IR Flash can follow Green Flash if the conditions are favorable. Since eyes are more sensitive to green than red, the former may have been noticed by more observers. It is also possible that this is an artifact of the camera firmware. It has also been suggested that car headlights are responsible, but I would not expect headlights to light up the entire sky. The top center of the image is very near the zenith and the evening sky was rather clear.