First results show that the RGS instruments work as expected, and that the spectral resolution is precisely as specified before launch. Of particular interest are emission-line objects. The spectrum below shows a superposition of approximately 200 ksec of exposure time obtained with RGS1 in February 2000 from the active binary star HR1099, a particularly bright and variable X-ray source. Time-variable features will indicate rotational modulation and plasma dynamics during events of explosive energy release, elemental abundance changes, density changes, etc. RGS1 spectrum of HR1099.
Most visible features are real rather than being of statistical nature.
Background has been subtracted. Wavelength scale is preliminary. Example of a strong emission line. All error bars are 1 sigma derived from Poissonian counting statistics. This image shows the high quality of well-exposed RGS spectra.