13.1 Introduction

The information in this chapter will help you select your grating configuration and observing slit and determine your observing plan (e.g., total required exposure time, and number of exposures). This chapter is basically organized by grating and slit (corresponding to Spectral Element and Aperture in the Phase II Proposal Instructions.)

For each grating mode the following are provided:

A brief description of the grating mode's specifications, including recommended uses and special considerations.
The central-wavelength settings and range of wavelength covered at each setting, together with the dispersions and plate scales.
Plots and tables of sensitivities and throughputs as a function of wavelength.
Plots of signal-to-noise as a function of V+STMAG_λ (the color-dependent correction from V magnitude to STMAG at wavelength λ), F_λ, and exposure time.

For each slit the following are provided:

A brief description of the slit's specifications, including recommended uses and special considerations.
Plots and tables of relative throughputs as a function of wavelength.

For representative grating-slit combinations we provide:

Tables of encircled energy for the flux in the default pipeline extraction aperture, and the percent flux contained in the peak pixel.
Plots of representative spatial (perpendicular to the dispersion) profiles at selected wavelengths.
Line spread functions and FWHM as a function of wavelength.

In addition,

Section 13.8 provides a summary of the screening brightness limits for the MAMA spectroscopic modes.

The sensitivities and dark currents adopted for calculating the figures and tables used in this chapter were projected before SM4 for a date of August 2008. Actual values for a given cycle will differ slightly. For the most up-to-date values, please consult the STIS ETC.

The next section explains the plots and tables found in the grating sections in this chapter.

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STIS Instrument Handbook
- • Acknowledgments
- Chapter 1: Introduction
  - • 1.1 Overview
  - • 1.2 Introduction to the Handbook
  - • 1.3 Handbook Layout
  - • 1.4 Proposal Preparations and Observations with STIS
  - • 1.5 The Help Desk at STScI
  - • 1.6 The STIS Web Pages and Support Information
  - • 1.7 Non-proprietary STIS Data
- Chapter 2: Special Considerations for Cycle 32
  - • 2.1 STIS Repair and Return to Operations
  - • 2.2 Summary of STIS Performance Changes Since 2004
  - • 2.3 New Capabilities for Cycle 32
  - • 2.4 Use of Available-but-Unsupported Capabilities
  - • 2.5 Choosing Between COS and STIS
  - • 2.6 Scheduling Efficiency and Visit Orbit Limits
  - • 2.7 MAMA Scheduling Policies
  - • 2.8 Prime and Parallel Observing: MAMA Bright-Object Constraints
  - • 2.9 STIS Snapshot Program Policies
- Chapter 3: STIS Capabilities, Design, Operations, and Observations
  - • 3.1 Instrument Capabilities
  - • 3.2 Instrument Design
  - • 3.3 Basic Instrument Operations
  - • 3.4 Designing STIS Observations
- Chapter 4: Spectroscopy
  - • 4.1 Overview
  - • 4.2 First-Order Long-Slit Spectroscopy
  - • 4.3 Echelle Spectroscopy in the Ultraviolet
  - • 4.4 Objective Prism Spectroscopy
- Chapter 5: Imaging
  - • 5.1 Imaging Overview
  - • 5.2 Optical CCD Imaging
  - • 5.3 Ultraviolet Imaging with the MAMA Detectors
  - • 5.4 Neutral Density Filters
- Chapter 6: Exposure Time Calculations
  - • 6.1 Overview
  - • 6.2 Determining Count Rates from Sensitivities
  - • 6.3 Throughput and Sensitivity
  - • 6.4 Computing Exposure Times
  - • 6.5 Detector and Sky Backgrounds
  - • 6.6 Tabular Sky Backgrounds
  - • 6.7 Extinction Correction
  - • 6.8 Exposure Time Examples
- Chapter 7: Feasibility and Detector Performance
  - • 7.1 STIS Detectors
  - • 7.2 The CCD
  - • 7.3 CCD Operation and Feasibility Considerations
  - • 7.4 The MAMA Detectors
  - • 7.5 MAMA Operation and Feasibility Considerations
  - • 7.6 MAMA Spectral and Spatial Offsetting
  - • 7.7 MAMA Bright Object Limits
- Chapter 8: Target Acquisition
  - • 8.1 Introduction
  - • 8.2 STIS Onboard CCD Target Acquisitions - ACQ
  - • 8.3 Onboard Target Acquisition Peakups - ACQ PEAK
  - • 8.4 Determining Coordinates in the International Celestial Reference System (ICRS) Reference Frame
  - • 8.5 Acquisition Examples
  - • 8.6 STIS Post-Observation Target Acquisition Analysis
- Chapter 9: Overheads and Orbit-Time Determination
  - • 9.1 Overview
  - • 9.2 STIS Exposure Overheads
  - • 9.3 Orbit Use Determination Examples
- Chapter 10: Summary and Checklist
  - • 10.1 Phase I Proposing
  - • 10.2 Phase II - Scheduling Approved Observations
- Chapter 11: Data Taking
  - • 11.1 Basic Operating Modes
  - • 11.2 Exposure Sequences and Contemporaneous Calibrations
  - • 11.3 Patterns and Dithering
  - • 11.4 Fixing Orientation on the Sky
  - • 11.5 Target Positioning
- Chapter 12: Special Uses of STIS
  - • 12.1 Slitless First-Order Spectroscopy
  - • 12.2 Long-Slit Echelle Spectroscopy
  - • 12.3 Time-Resolved Observations
  - • 12.4 Observing Too-Bright Objects with STIS
  - • 12.5 High Signal-to-Noise Ratio Observations
  - • 12.6 Improving the Sampling of the Line Spread Function
  - • 12.7 Considerations for Observing Planetary Targets
  - • 12.8 Special Considerations for Extended Targets
  - • 12.9 Parallel Observing with STIS
  - • 12.10 Coronagraphic Spectroscopy
  - • 12.11 Coronagraphic Imaging - 50CORON
  - • 12.12 Spatial Scans with the STIS CCD
- Chapter 13: Spectroscopic Reference Material
  - • 13.1 Introduction
  - • 13.2 Using the Information in this Chapter
  - 13.3 Gratings
    - • First-Order Grating G750L
    - • First-Order Grating G750M
    - • First-Order Grating G430L
    - • First-Order Grating G430M
    - • First-Order Grating G230LB
    - • Comparison of G230LB and G230L
    - • First-Order Grating G230MB
    - • Comparison of G230MB and G230M
    - • First-Order Grating G230L
    - • First-Order Grating G230M
    - • First-Order Grating G140L
    - • First-Order Grating G140M
    - • Echelle Grating E230M
    - • Echelle Grating E230H
    - • Echelle Grating E140M
    - • Echelle Grating E140H
    - • PRISM
    - • PRISM Wavelength Relationship
  - 13.4 Apertures
    - • 52X0.05 Aperture
    - • 52X0.05E1 and 52X0.05D1 Pseudo-Apertures
    - • 52X0.1 Aperture
    - • 52X0.1E1 and 52X0.1D1 Pseudo-Apertures
    - • 52X0.2 Aperture
    - • 52X0.2E1, 52X0.2E2, and 52X0.2D1 Pseudo-Apertures
    - • 52X0.5 Aperture
    - • 52X0.5E1, 52X0.5E2, and 52X0.5D1 Pseudo-Apertures
    - • 52X2 Aperture
    - • 52X2E1, 52X2E2, and 52X2D1 Pseudo-Apertures
    - • 52X0.2F1 Aperture
    - • 0.2X0.06 Aperture
    - • 0.2X0.2 Aperture
    - • 0.2X0.09 Aperture
    - • 6X0.2 Aperture
    - • 0.1X0.03 Aperture
    - • FP-SPLIT Slits 0.2X0.06FP(A-E) Apertures
    - • FP-SPLIT Slits 0.2X0.2FP(A-E) Apertures
    - • 31X0.05ND(A-C) Apertures
    - • 0.2X0.05ND Aperture
    - • 0.3X0.05ND Aperture
    - • F25NDQ Aperture
  - 13.5 Spatial Profiles
    - • First-Order Spatial Profiles
    - • Echelle Spatial Profiles
  - 13.6 Line Spread Functions
    - • First-Order Line Spread Functions
    - • Echelle Line Spread Functions
  - • 13.7 Spectral Purity, Order Confusion, and Peculiarities
  - • 13.8 MAMA Spectroscopic Bright Object Limits
- Chapter 14: Imaging Reference Material
  - • 14.1 Introduction
  - • 14.2 Using the Information in this Chapter
  - 14.3 CCD
    - • CCD Clear Imaging - 50CCD
    - • CCD Long-Pass Imaging F28X50LP
    - • F28X50OIII - CCD
    - • F28X50OII - CCD
    - • 50CORON - Clear CCD
  - 14.4 NUV-MAMA
    - • 25MAMA - NUV-MAMA, Clear
    - • F25ND3 - NUV-MAMA
    - • F25ND5 - NUV-MAMA
    - • F25NDQ - NUV-MAMA
    - • F25QTZ - NUV-MAMA, Longpass
    - • F25SRF2 - NUV-MAMA, Longpass
    - • F25MGII - NUV-MAMA
    - • F25CN270 - NUV-MAMA
    - • F25CIII - NUV-MAMA
    - • F25CN182 - NUV-MAMA
  - 14.5 FUV-MAMA
    - • 25MAMA - FUV-MAMA, Clear
    - • 25MAMAD1 - FUV-MAMA Pseudo-Aperture
    - • F25ND3 - FUV-MAMA
    - • F25ND5 - FUV-MAMA
    - • F25NDQ - FUV-MAMA
    - • F25QTZ - FUV-MAMA, Longpass
    - • F25QTZD1 - FUV-MAMA, Longpass Pseudo-Aperture
    - • F25SRF2 - FUV-MAMA, Longpass
    - • F25SRF2D1 - FUV-MAMA, Longpass Pseudo-Aperture
    - • F25LYA - FUV-MAMA, Lyman-alpha
  - • 14.6 Image Mode Geometric Distortion
  - • 14.7 Spatial Dependence of the STIS PSF
  - • 14.8 MAMA Imaging Bright Object Limits
- Chapter 15: Overview of Pipeline Calibration
  - • 15.1 Pipeline Processing Overview
  - • 15.2 How Phase II Parameter Choices Affect Calibration
  - • 15.3 More Detailed Information
- Chapter 16: Accuracies
  - • 16.1 Summary of Accuracies
- Chapter 17: Calibration Status and Plans
  - • 17.1 Introduction
  - • 17.2 Ground Testing and Calibration
  - • 17.3 STIS Installation and Verification (SMOV2)
  - • 17.4 Cycle 7 Calibration
  - • 17.5 Cycle 8 Calibration
  - • 17.6 Cycle 9 Calibration
  - • 17.7 Cycle 10 Calibration
  - • 17.8 Cycle 11 Calibration
  - • 17.9 Cycle 12 Calibration
  - • 17.10 SM4 and SMOV4 Calibration
  - • 17.11 Cycle 17 Calibration Plan
  - • 17.12 Cycle 18 Calibration Plan
  - • 17.13 Cycle 19 Calibration Plan
  - • 17.14 Cycle 20 Calibration Plan
  - • 17.15 Cycle 21 Calibration Plan
  - • 17.16 Cycle 22 Calibration Plan
  - • 17.17 Cycle 23 Calibration Plan
  - • 17.18 Cycle 24 Calibration Plan
  - • 17.19 Cycle 25 Calibration Plan
  - • 17.20 Cycle 26 Calibration Plan
  - • 17.21 Cycle 27 Calibration Plan
  - • 17.22 Cycle 28 Calibration Plan
  - • 17.23 Cycle 29 Calibration Plan
  - • 17.24 Cycle 30 Calibration Plan
  - • 17.25 Cycle 31 Calibration Plan
- Appendix A: Available-But-Unsupported Spectroscopic Capabilities
  - • A.1 Introduction
  - • A.2 Full Aperture Complement
  - • A.3: Additional Available-but-Unsupported Options
- • Glossary

13.1 Introduction

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