Hello fellow amateur and professional astronomers,
On July July 17, 2017, I was at an observing session in Avrig, Sibiu county, Romania (45.7288° N, 24.3784° E). At approx 11:30 pm I pointed my green laser pointer (class III, wavelength 532 nm +/-10, YL-Laser 303) towards Arcturus in order to help my colleague align the SW AZEQ 5 mount within the 3-star procedure.
While the laser beam was on, at approx 1 arcminute beneath and to the left from Arcturus, with my naked eye, I observed a point of light (white/blueish) lighting up to the point which I estimate to be close to the visual magnitude of Jupiter or slightly higher for appprox 5 seconds, and then the "flare" faded out to black. As there was no "regular" star-like remanant, I was left to conclude that the initial flare did not originate from a star.
I ruled out a reflection of the laser beam from a satelite (as too far for my laser's power), a plane or a bird (due to the white/blueish light I saw, its fixed position and apparent distance to my eye), as well the possibility of a meteorite burst (as it had no apparent trajectory, but it appeared as a fixed point).
I am so intrigued and curious as to what possible optics or physics could have been involved and explanations or ideas you may have to explain the phenomenon?
I searched online for others' possible similar observations without success.