Glossary

ARD - Ascii Region Description. A method of describing a spatial region in a text file.
GUI - Graphical User Interface.
HRI - High Resolution Imager.
LEDAS - Leicester Database and Archive Service.
MPE - Max-Planck institute at Garching bei Munchen.
PSF - Point spread function. The scattering of photons from a source due to mirror irregularities and detector response.
PSPC - Position Sensitive Proportional Counter.
RDAC - ROSAT Data Archive Centre.
ROD - ROSAT Observation Dataset.
US - United States of America.
Vignetting - The decline in detection efficiency with increasing off-axis angle. Primarily due to XRT mirror reflectivity.