X-ray spectral variability of 3C273.

3C273 has been monitored by EXOSAT over the period December 1983 to June 1984 in 4 observations. In the December observation the flux was high and the spectrum showed a power law index of 1.5 changing to 0.9 at∼8 keV. In subsequent observations the flux dropped to∼40% of its original value and the hard tail disappeared. In the last observation the LE flux increased by a factor of 2 with no accompanying ME flux increase. [ABSTRACT FROM AUTHOR]