I was at work in a dark yard in errol, between perth and dundee in scotland. it was dark outside and noticed the stars. all of a sudden there was a bright white flash in the sky towards the south above the river tay. i noticed that this was from a small pin of light in the sky which was moving slowly to the south east. i noticed that it would slowly pulsate yellow/white light and then flash a bright blue/white light. immediately after one of the flashes the object had moved in the sky a considerable distance parallel to its previous line of travel. this happened immediately as there was the flash, then it was pulsating in a different direction. the pulsating and flashing happened at random. the object carried on its course then all of a sudden streaked in a “z” like shape to another area of the sky and carried on in the same direction whilst pulsating and flashing until it was out of sight and obscured by cloud cover. i would estimate that the object was too high to be a conventional aircraft. there was no noise from the object. it’s speed wasn’t terribly fast until it moved its position in the sky and then zig zagged.