Our astronomy club site for our star parties was in an area that had a natural gas pipeline with a mercaptan injection system fairly close by. I never saw the thing in more than twilight. At night it was just pitch black and we could not see it but we could hear the valves and pumps making noises. Every once and a while it must need to burp because it would stink like crazy and then it would be less stinky. It was a super dark site.
