X-ray intensity-hardness correlation in Cyg X-1

Linqing Wen, Wei Cui, Hale V. Bradt

Using data from the All-Sky Monitor aboard the Rossi X-ray Timing Explorer (RXTE), we found that the 1.5-12 keV X-ray count rate of Cyg X-1 is, on time scales from 90 seconds to at…