1. Steward Observatory, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721, USA
2. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
3. Department of Physics and Astronomy, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
4. National Optical Astronomy Observatory, Tucson, AZ 85719, USA
5. CCPP, New York University, 4 Washington Place, New York, NY 10003, USA
6. Center for Urban Science and Progress, New York University, 1 MetroTech Center, Brooklyn, NY 11201, USA
7. Núcleo de Astronomia de la Facultad de Ingenieria, Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile
8. Millennium Institute of Astrophysics, Santiago, Chile
9. Event Horizon Telescope, Smithsonian Astrophysical Observatory MS 42, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
10. Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Colina El Pino S/N, La Serena, Chile
11. Universidad de La Laguna, Tenerife, Spain