|STIS Instrument Handbook for Cycle 25|
The STIS Instrument Handbook is the basic reference manual for the Space Telescope Imaging Spectrograph; it describes the instrument’s properties, performance, operations, and calibration. The Handbook is maintained by the STIS team at STScI. Wherever possible, the most recent operational data have been incorporated into this revised edition.
• This Handbook is not meant to serve as a manual for the reduction and analysis of data taken with STIS. The STIS Data Handbook (available from the STScI Help Desk or the STIS website) describes how to work with STIS data.1.2.1 Document ConventionsThis document follows the usual STScI convention in which terms, words, and phrases which are to be entered by the user in a literal way on an HST proposal are shown in a typewriter font (e.g., STIS/CCD, SHADOW). Names of software packages or commands (e.g., calstis) are given in boldface.Wavelengths in this Handbook and in STIS data products are always measured in vacuum conditions. Wavelength units in this Handbook are in Angstroms (Å).The Handbook uses six observational examples to illustrate various scenarios such as calculation of exposure times, estimation of overheads, etc. throughout the text. The examples are:
• In addition, we use stellar spectra throughout the Handbook to illustrate signal-to-noise ratio calculations and derive limiting magnitudes. Figure 1.1 shows the normalized spectra of O, A, G, and M stars from an observed catalog of stars (for details, see Buser, 1978, A&A, 62, 411) which are used in the Handbook examples.Many of the performance characteristics of STIS change over time. These changes include gradual decreases in optical throughput, increases in detector dark currents, and decreasing charge transfer efficiencies. Most of the figures and tables illustrating throughputs, signal-to-noise calculations, bright object limits, and limiting magnitudes had been recalculated for the Cycle 17 version of this Handbook based on the best available performance estimates for Cycle 17. Except where otherwise noted these tables and figures have not been updated for the additional changes expected for Cycle 25. In most cases the differences will be modest. For more up-to-date performance estimates, it is suggested that users consult the STIS ETCs available at:The sensitivities and other instrument parameters adopted for use with the Cycle 25 ETCs are our best estimates for April 2018 (i.e. mid-Cycle 25).Figure 1.1: Spectra of O5V, A0V, G0V, and M0V Stars.