1. David A. Dunlap Department of Astronomy and Astrophysics, University of Toronto, 50 St. George St., Toronto ON M5S 3H4, Canada
2. Sapienza University of Rome, Physics Department, Piazzale Aldo Moro 5, I-00185 Rome, Italy
3. Green Bank Observatory, 155 Observatory Road, Green Bank, WV 24944, USA
4. Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104, USA
5. Centre for the Universe, Perimeter Institute, Waterloo ON N2L 2Y5, Canada
6. Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90007, USA
7. European Southern Observatory (ESO), Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany
8. Quantum Sensors Group, National Institute of Standards and Technology, Boulder, CO 80305, USA
9. Department of Astronomy, Cornell University, Ithaca, NY 14853, USA
10. Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George St., Toronto ON M5S 3H4, Canada
11. School of Physics and Astronomy, Cardiff University, The Parade, Cardiff CF24 3AA, UK
12. Joseph Henry Laboratories of Physics, Jadwin Hall, Princeton University, Princeton, NJ 08544, USA
13. Department of Astrophysical Sciences, Princeton University, Peyton Hall, Princeton, NJ 08544, USA
14. Instituto de Astrofísica and Centro de Astro-Ingeniería, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile
15. Department of Physics, Cornell University, Ithaca, NY 14850, USA
16. INAF – Osservatorio Astronomico di Cagliari, Via della Scienza 5, I-09047 Selargius (CA), Italy
17. Department of Physics, Columbia University, New York, NY 10027, USA
18. Center for Computational Astrophysics, Flatiron Institute, New York, NY 10010, USA
19. Astrophysics Research Centre, University of KwaZulu-Natal, Westville Campus, Durban 4041, South Africa
20. Department of Physics and Astronomy, Rutgers, the State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854-8019, USA
21. Dunlap Institute of Astronomy and Astrophysics, 50 St. George St., Toronto ON M5S 3H4, Canada
22. National Radio Astronomy Observatory, 520 Edgemont Rd., Charlottesville, VA 22903, USA
23. Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637, USA
24. Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637, USA
25. Department of Physics, University of Chicago, Chicago, IL 60637, USA
26. Enrico Fermi Institute, University of Chicago, Chicago, IL 60637, USA
27. School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal, Westville Campus, Durban 4041, South Africa
28. Physics Department, Stanford University, Stanford, CA 94305, USA
29. Kavli Institute for Particle Astrophysics and Cosmology, Stanford, CA 94305, USA
30. Department of Astronomy, University of Virginia, 530 McCormick Road, Charlottesville, VA 22904-4325, USA
31. Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
32. Department of Physics, McGill University, 3600 rue University, Montréal QC H3A 2T8, Canada
33. McGill Space Institute, McGill University, 3550 rue University, Montréal QC H3A 2A7, Canada
34. School of Chemistry and Physics, University of KwaZulu-Natal, Westville Campus, Durban 4000, South Africa
35. Instituto de Física, Pontificia Universidad Católica de Valparaíso, Casilla 4059, Valparaíso, Chile
36. School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA
37. NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
38. MIT Kavli Institute, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA