March 19, 2018: Drs. Gregory Sivakoff (University of Alberta), Poshak Gandhi (University of Southampton), and Diego Altamirano (University of Southampton) have requested AAVSO observers' assistance in monitoring the new black hole X-ray binary candidate ASASSN-18ey = MAXI J1820+070.
black hole binary
Four AAVSO members listed as co-authors in Nature paper
V404 Cygni has been known as a variable star residing in the constellation Cygnus since the 18th century. It was believed to be a nova, a compact binary system containing a white dwarf primary and a sun-like secondary star, that undergoes unpredictable episodes of dramatic brightening - or 'outbursts' - before settling back down to quiescence for decades, until the next outburst.