9.1 Introduction to STIS

The Instrument Configurations and Operating Modes described here are used for the Visit and Exposure Specifications. The legal Specifications are discussed in a summary fashion in the following sections. More complete descriptions of Instrument Configurations, Modes, Apertures, Spectral Elements, etc. are available in the STIS Instrument Handbook.

Note that many of the Optional Parameters have default values; in such cases, an entry for an Optional Parameter in the Visit and Exposure Specifications is necessary only if it is desired to override the default value. In the STScI proposal system, the physical units of Optional Parameter quantities are always implicit and should never be entered by the observer.

STIS has a large number of apertures. A complete list of supported apertures is provided at the end of this chapter (see Table 9.5 on page 180). That table should be taken as definitive if any additional information in this chapter appears to conflict.

Table 9.1 lists the permitted Instrument Configurations, Operating Modes, Spectral Elements, and Optional Parameters for the STIS.

Note also that in addition to the automatic wavelength calibrations added by the system, the following observer-added contemporaneous calibrations may also be made:

•	CCDFLAT (fringe flats) for G750L and G750M observations longward of 7000 е.

•	WAVE calibrations for added wavelength precision.

See the STIS Instrument Handbook for more information.

Some STIS modes will work without an initial ACQuisition (such as slitless spectroscopy and imaging), but in general the user must ensure that ACQuisitions are included where needed. An ACQ/PEAK should always be preceded by an ACQuisition.

STIS Optional Parameters

Table 9.1: Supported Optional Parameters for STIS Instrument Modes

Config.	Mode	Spectral Elements	Optional Parameters
STIS/CCD	ACQ	MIRROR	ACQTYPE, DIFFUSE–CENTER, CHECKBOX
	ACQ/PEAK	MIRROR, G230LB, G230MB, G430L, G430M, G750L, G750M	SIZEAXIS2
	ACCUM		CR–SPLIT, GAIN, BINAXIS1, BINAXIS2, SIZEAXIS2
STIS/FUV– MAMA	ACCUM	MIRROR, G140L, G140M, E140M, E140H	BINAXIS1, BINAXIS2
	TIME–TAG		BUFFER–TIME
STIS/NUV– MAMA	ACCUM	MIRROR, G230L, G230M, E230M, E230H, PRISM	BINAXIS1, BINAXIS2
	TIME–TAG		BUFFER–TIME

 

The following sections provide further details of the entries to be made on the Visit and Exposure Specifications when a particular STIS/CCD, STIS/FUV–MAMA, or STIS/NUV–MAMA Mode/Configuration is chosen.

Note: The AXIS1 and AXIS2 coordinate system is defined in Section 3.1 of the STIS Instrument Handbook. Array sizes are given as AXIS1 x AXIS2. For CCD and MAMA first-order grating and MAMA echelle spectroscopic modes, AXIS1 is in the dispersion direction, and AXIS2 is in the "cross-dispersion" (or spatial) direction.