The fading superorbital clock of Hercules X-1 in its 2025--2026 extended low state

Zhenxuan Liao, Xinrui Tie, Yufeng Chi +1

We present two decades of X-ray monitoring of the eclipsing accreting pulsar Hercules X-1 with \textit{Fermi}/GBM, \textit{Swift}/BAT and \textit{MAXI}/GSC, centred on the extended…