Steve Kahn
Columbia University Astrophysics Laboratory

The XMM-Newton Observatory is a major facility-class X-ray space observatory developed by the European Space Agency. It was launched on an ARIANE V rocket in December of last year. The satellite carries three large grazing incidence telescopes and associated scientific instruments, including a Reflection Grating Spectrometer (RGS) partially designed and built at Columbia University. The RGS has provided some of the first high resolution spectra of cosmic sources in the soft X-ray band, which includes a wealth of atomic transitions of multiply charged ions of the abundant elements carbon through iron. Data have already been acquired on a diverse array of sources ranging from normal stars to distant quasars. I will review the details of the instrument and discuss a few examples where the newly acquired X-ray spectra have significantly challenged our conventional understanding of the sources involved.