The thread https://www.physicsforums.com/threads/how-close-is-earth-to-the-closest-black-hole.939912/reached a conclusion that there is a 65% confidence level that there is one black hole within 50 ly of Earth. The link http://www.solstation.com/stars/s20ly.htmsays there are 25 stars bigger than red dwarfs within 20 ly. Extrapolating to a sphere centered on Earth with a 100 ly radius, this sphere should contain about 625 stars bigger than red dwarfs and 8 black holes, of which about 4 would be in binary systems. Systematically observing the Doppler shifts for these 625 stars over a period of time should detect any invisible massive companions. Is such a search currently happening or planned?