8.1 Introduction to STIS
HST observations with STIS are specified using the Astronomer's Proposal Tool (APT), and this article provides instructions for completing those observations. |
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Format definitions
Boldface type indicates the name of an APT parameter or a value for a parameter.
Black text indicates an important note.
Magenta text indicates available but unsupported parameters (requires prior approval from STScI).
Red text indicates restricted parameters (for STScI use only).
Brown text indicates text file parameters.
Items in brackets - <value> - are required values.
Items in square brackets - [<value>] - are optional.
Introduction
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 in table Table 8.7: Supported STIS Apertures. That table should be taken as definitive if any additional information in this chapter appears to conflict.
Table 8.1: Supported Optional Parameters for STIS Instrument Modes 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 Å.
- WAVE calibrations either for added wavelength precision or to replace auto WAVECALs to control when they execute. 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 8.1: 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, WAVECAL | ||
STIS/FUV– MAMA | ACCUM | MIRROR, G140L, G140M, E140M, E140H | BINAXIS1, BINAXIS2, WAVECAL |
TIME–TAG | BUFFER–TIME, WAVECAL | ||
STIS/NUV– MAMA | ACCUM | MIRROR, G230L, G230M, E230M, E230H | BINAXIS1, BINAXIS2, WAVECAL |
TIME–TAG | BUFFER–TIME, WAVECAL |
Table 8.1: For available but unsupported parameters
Table 8.1: For restricted parameters
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 or STIS Mode/Configuration is chosen.
Note: The AXIS1 and AXIS2 coordinate system is defined in Figure 8.1: STIS Coordinate System. 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.
Related Links
8.2 Target Acquisition Modes
8.3 Imaging and Spectroscopy
8.4 STIS Restricted Engineering Modes
8.5 STIS Reference Information