X-ray Luminosity and Absorption Column Fluctuations in the H2O Maser Galaxy NGC 4258 from Weeks to Years

Antonella Fruscione, Lincoln J. Greenhill, Alexei V. Filippenko +3

We report monitoring of the 0.3-10 keV spectrum of NGC4258 with XMM over 1.5 years.We als o report reprocessing of an overlapping series of archival Chandra observations. By includ…