As we are now in the period when Perseid meteors are likely to appear I've decided to use my wider 28mm lens to stand more chance of picking one up. No luck so far with meteors but another mystery single flash was detected (visible lower right).
I have found that sometimes the camera itself can occasionally generate a bit of random noise (other than hot pixels) but such noise is quite easy to identify on enlargement. My 28mm lens suffers some CA around the edges when wide open which shows as offset spots of red. This particular object has an associated red spot so confirms it came via the lens.
animated gif. 1.49mb
Lens 28mm. 30 second exposures
(click thumbnail for large version)