An analysis of the long-term X-ray activity of the ultra-compact binary 4U 1820-30 within the years 1996-2002 is presented. Episodes of brief low states (BLS), lasting for several days, are superposed on the general course of the 172.780 day cycle.
An analysis of the long-term X-ray activity of the ultra-compact binary 4U 1820-30 within the years 1996-2002 is presented. Episodes of brief low states (BLS), lasting for several days, are superposed on the general course of the 172.780 day cycle. (en)