A.1 Introduction

STIS provides additional Available-but-Unsupported capabilities beyond those which will be routinely supportedSection 2.4 describes the distinctions between supported and available-but-unsupported modes and the policies regarding use of the latter.  A mode is a combination of aperture, optical element (and central wavelength setting), and detector.

This appendix to the STIS Instrument Handbook indicates which modes are supported and gives information about the additional Available-but-Unsupported modes of STIS. Since all of the imaging capabilities are supported (apart from special use case of coronagraphic imaging, see Section 12.11), it contains information relevant to spectroscopic observations only. As detailed in Section A.2, numerous entrance slits or apertures are supported for a limited set of optical elements and available for others, or are used in available mode only. A small number of central wavelength settings have been removed from the set of supported settings due to difficulties with them (e.g., order overlap).  Section A.3 lists several additional available-but-unsupported capabilities that have been used in some recent programs.