... Tonight's Sky . ... Observing . ... Star Atlas . ... Behemoth black hole found in an unlikely place . ... First gamma-ray clock found . ... The gamma-ray signal is strongest when the compact object (thought to be a black hole) is in front of the star as seen from Earth and weakest when it is behind the star. ... Only registered members of Astronomy.com are allowed to comment on this article. ... Receive news, sky-event information, observing tips, and more from Astronomy's weekly email newsletter. ...