The PANTER X-ray Test Facility was originally designed to support the development and construction of the
ROSAT mirror system. A large instrument chamber (length 12 m, diameter 3.5m) accommodates the optics
to be analysed. The X-ray sources covering an 0.2 - 50 keV energy range are located at a distance of 123m
from the entrance to the chamber to provide an almost parallel X-ray beam. Both are connected by a vacuum
tube of 1m diameter. In addition to ROSAT a large number of astronomical systems like telescopes for Exosat,
BeppoSAX, JET-X, ABRIXAS, XMM-Newton and Swift - but also gratings (e.g., LETG on Chandra), filters,
and focal plane detectors have been measured at the facility. As a "growing facility" we are currently planning to
apply changes to the facility layout to support measurements of instrumentation for future missions like XEUS.
Currently a parallel beam is set up using a spare CDS mirror ("Coronal Diagnostic Spectrometer", for the SOHO
mission) as condensor. Moreover, extensions to vacuum tube and instrument chamber are under consideration,
both to allow calibration of systems with focal lengths significantly longer than XMM-Newton. A new focal plane
camera using a CCD developed for the eROSITA mission will improve spatial and spectral resolution. Finally,
the energy coverage shall be extended to lower and to higher energies. Already with the present configuration
important issues like performance under low temperatures could be investigated.