Chandra observations of the narrow-line Seyfert 1 galaxy RX J2217.9-5941

We report the results of two Chandra ACIS-S observations from 2003 February and August of the highly X-ray variable narrow-line Seyfert 1 galaxy RX J2217.9-5941. Observations spanning the time from the ROSAT All-Sky Survey (RASS) through an ASCA observation in 1998 indicate apparently monotonically decreasing flux by a factor of 30. The Chandra observations reveal increased emission over that seen with ASCA, supporting a persistent variability rather than an X-ray outburst event. However, the cause of the strong X-ray variability remains unclear. Our Chandra observations confirm the steep soft X-ray spectrum in the 0.2-2.0 keV band found during the RASS observation (alpha(X) = 2.7). The spectral shape of the source appears to be variable, with the spectrum becoming softer when the source becomes fainter. Best-fitting models to the data include an absorbed broken power law, a blackbody plus a power law, and a power law with partial covering absorption. The latter model suggests a variable partial covering absorber in the line of sight, which can explain in part the variability seen in RX J2217.9-5941. We suggest that there might be a population of narrow-line Seyfert 1 galaxies that are, at least at times, highly absorbed.