STIS Instrument Handbook for Cycle 27
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Table of Contents

Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 27
Chapter 1: Introduction
1.1 Overview
1.2 Introduction to the Handbook
1.2.1 Document Conventions
1.2.2 Examples Used in this Handbook
1.3 Handbook Layout
1.4 Proposal Preparations and Observations with STIS
1.4.1 The STIS Team at STScI
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 Considerationsfor Cycle 27
2.1 STIS Repair and Return to Operations
2.2 Summary of STIS Performance Changes Since 2004
2.3 New Capabilities for Cycle 27
2.4 Use of Available-but-Unsupported Capabilities
2.5 Should I Use COS or 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
3.2.1 Detectors
3.2.2 STIS Physical Configuration
3.3 Basic Instrument Operations
3.3.1 Typical STIS Observing Sequence
3.4 Designing STIS Observations
3.4.1 Identify Science Requirements and Define STIS Configuration
3.4.2 Determine Exposure Time and Check Feasibility
3.4.3 Identify Need for Non-Science Exposures and Constraints
3.4.4 Determine Total Orbit Request
Chapter 4: Spectroscopy
4.1 Overview
4.1.1 Throughputs
4.1.2 Limiting Magnitudes
4.1.3 Saturation
4.1.4 MAMA Bright Object Limits
4.1.5 Scanned Gratings: Prime and Secondary (Tilt) Positions
4.1.6 Cross-Over Regions
4.1.7 Neutral Density Slits for Spectroscopy
4.2 First-Order Long-Slit Spectroscopy
4.2.1 Gratings for First-Order Spectroscopy
4.2.2 Slits for First-Order Spectroscopy
4.2.3 STIS Pseudo-Aperture Positions
4.2.4 Detailed First-Order Spectroscopic Information
4.3 Echelle Spectroscopy in the Ultraviolet
4.3.1 Echelle Gratings
4.3.2 Slits for Echelle Spectroscopy
4.3.3 Detailed Echelle Information
4.4 Objective Prism Spectroscopy
Chapter 5: Imaging
5.1 Imaging Overview
5.1.1 Caveats for STIS Imaging
5.1.2 Throughputs and Limiting Magnitudes
5.1.3 Signal-To-Noise Ratios
5.1.4 Saturation
5.2 Optical CCD Imaging
5.2.1 Effect of the Optical Baffles on STIS CCD Imaging
5.2.2 Unfiltered (Clear) CCD Imaging: 50CCD & 50CORON
5.2.3 Optical Longpass: F28X50LP
5.2.4 [O III]: F28X50OIII
5.2.5 [O II]: F28X50OII
5.3 Ultraviolet Imaging with the MAMA Detectors
5.3.1 Bright Object Limits
5.3.2 Optical Performance
5.3.3 Unfiltered (Clear) MAMA Imaging: 25MAMA
5.3.4 FUV Red Leak
5.3.5 Longpass-Filtered MAMA Imaging: F25SRF2 and F25QTZ
5.3.6 MAMA Narrow-Band-Filtered Imaging
5.4 Neutral Density Filters
Chapter 6: Exposure Time Calculations
6.1 Overview
6.1.1 The STIS Exposure Time Calculators
6.2 Determining Count Rates from Sensitivities
6.2.1 Spectroscopy
6.2.2 Imaging
6.3 Throughput and Sensitivity
6.4 Computing Exposure Times
6.4.1 Calculating Exposure Times for a Given Signal-to-Noise
6.5 Detector and Sky Backgrounds
6.5.1 Detector Backgrounds
6.5.2 Sky Background
6.6 Tabular Sky Backgrounds
6.7 Extinction Correction
6.8 Exposure Time Examples
6.8.1 Spectroscopy of Diffuse Source (M86)
6.8.2 Spectroscopy of Solar-Analog Star P041-C
6.8.3 Extended Source with Flux in cgs Units (NGC 6543): Imaging and Spectroscopy
6.8.4 Echelle Spectroscopy of a Bright Star, Reddened LMC Star
6.8.5 Imaging a Faint Stellar Source
6.8.6 Time-Tag Observations of a Flare Star (AU Mic)
Chapter 7: Feasibility and Detector Performance
7.1 STIS Detectors
7.2 The CCD
7.2.1 Detector Properties
7.2.2 Effects of the Change to STIS Side-2 Electronics on CCD Performance
7.2.3 STIS CCD Performance After Repair During SM4
7.2.4 CCD Spectral Response
7.2.5 CCD Sensitivity
7.2.6 CCD Long Wavelength Fringing
7.2.7 Fringing Due to the Order Sorter Filters
7.2.8 Optical Performance
7.2.9 Readout Format
7.2.10 Analog-to-Digital Conversion: Selecting the CCDGAIN
7.3 CCD Operation and Feasibility Considerations
7.3.1 CCD Dark Current
7.3.2 CCD Saturation
7.3.3 CCD Shutter Effects
7.3.4 Cosmic Rays
7.3.5 Hot Pixels
7.3.6 CCD Bias Subtraction and Amplifier Non-Linearity
7.3.7 Charge Transfer Efficiency
7.3.8 Mitigation of CTE Loss for Long-Slit Spectroscopy
7.3.9 Pixel-Based CTI Corrections for the STIS CCD
7.3.10 Ultraviolet Light and the STIS CCD
7.4 The MAMA Detectors
7.4.1 MAMA Properties
7.4.2 MAMA Spectral Response
7.4.3 MAMA Sensitivity
7.4.4 Optical Performance
7.5 MAMA Operation and Feasibility Considerations
7.5.1 MAMA Saturation—Overflowing the 16 Bit Buffer
7.5.2 MAMA Darks
7.5.3 MAMA Signal-to-Noise Ratio Limitations
7.5.4 MAMA Non-linearity
7.6 MAMA Spectral Offsetting
7.6.1 FUV First-Order Spectral Offset to Avoid Repeller Wire
7.6.2 Monthly Spectral Offsetting of All MAMA Modes
7.7 MAMA Bright Object Limits
7.7.1 Overview
7.7.2 Observational Limits
7.7.3 How Do You Determine if You Violate a Bright Object Limit?
7.7.4 Policy and Observers’ Responsibility in Phase I and Phase II
7.7.5 Policy on Observations That Fail Because they Exceed Bright Object Limits
7.7.6 What To Do If Your Source is Too Bright for Your Chosen Configuration?
7.7.7 Bright Object Protection for Solar System Observations
Chapter 8: Target Acquisition
8.1 Introduction
8.1.1 Initial Pointing
8.1.2 Acquisitions
8.1.3 Peakups
8.1.4 Drift Rates
8.2 STIS Onboard CCD Target Acquisitions (ACQ)
8.2.1 How it Works
8.2.2 Target Location Algorithms
8.2.3 Selecting Target Acquisition Parameters
8.2.4 Specifying Acquisitions in Phase II
8.2.5 Solar System Acquisitions
8.3 Onboard Target Acquisition Peakups (ACQ/PEAK)
8.3.1 Selecting Peakup Parameters
8.3.2 Specifying Acquisition Peakups in Phase II
8.4 Determining Coordinates in the Guide Star Selection System (GSSS) Reference Frame
8.5 Acquisition Examples
8.5.1 Point Source Acquisition of an Isolated Object
8.5.2 Point Source Acquisition of Bright, Isolated Object with CCD Dispersed Light Peakup
8.5.3 Diffuse Source Acquisition of a Spiral Galaxy
8.5.4 Point Source Acquisition in a Crowded Field
8.5.5 Point Source Acquisition of a QSO with Fuzz Behind the Fiducial Bar
8.5.6 Point Source Acquisition of a Bright, Isolated Star Into the Wedge
8.6 STIS Post-Observation Target Acquisition Analysis
8.6.1 Did the Acquisition Succeed?
Chapter 9: Overheads and Orbit-Time Determination
9.1 Overview
9.2 STIS Exposure Overheads
9.3 Orbit Use Determination Examples
9.3.1 Sample Orbit Calculation 1: Long-Slit Spectroscopy of the Galaxy M86
9.3.2 Sample Orbit Calculation 2: Low Dispersion Spectroscopy of Solar Analog Star P041-C
9.3.3 Sample Orbit Calculation 3: Imaging and Spectroscopy of the Cat’s Eye Planetary Nebula, NGC 6543
9.3.4 Sample Orbit Calculation 4: MAMA Echelle Spectroscopic Exposures in the CVZ
9.3.5 Sample Orbit Calculation 5: Faint CCD Imaging
Chapter 10: Summary and Checklist
10.1 Phase I Proposing
10.1.1 Phase I Orbit Allocation Examples
10.2 Phase II—Scheduling Approved Observations
Chapter 11: Data Taking
11.1 Basic Operating Modes
11.1.1 CCD ACCUM Mode
11.1.2 MAMA ACCUM Mode
11.1.3 MAMA TIME-TAG Mode
11.2 Exposure Sequences and Contemporaneous Calibrations
11.2.1 Auto-Wavecals
11.2.2 CR-SPLIT
11.2.3 Fringe Flat Fields
11.2.4 Repeat Exposures
11.3 Patterns and Dithering
11.3.1 STIS Imaging Patterns
11.3.2 STIS Spectroscopic Patterns
11.3.3 Generic Patterns
11.3.4 Combining Patterns
11.3.5 Dither Strategies
11.4 Fixing Orientation on the Sky
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
12.5.1 Dithering
12.5.2 FP-SPLIT Slits for Echelle Observations
12.6 Improving the Sampling of the Line Spread Function
12.7 Considerations for Observing Planetary Targets
12.7.1 Slit Orientation
12.8 Special Considerations for Extended Targets
12.9 Parallel Observing with STIS
12.9.1 Coordinated Parallels: Using STIS in Parallel with Other Instruments
12.10 Coronagraphic Spectroscopy
12.11 Coronagraphic Imaging—50CORON
12.12 Spatial Scans with the STIS CCD
12.12.1 Why use spatial scans with STIS?
12.12.2 Possible STIS Spatial Scan Use Cases
12.12.3 Using STIS spatial scans
Chapter 13: Spectroscopic Reference Material
13.1 Introduction
13.2 Using the Information in this Chapter
13.2.1 Wavelength Ranges
13.2.2 Grating Sensitivities and Throughputs
13.2.3 Signal-To-Noise Plots
13.2.4 Plate Scales
13.2.5 Apertures
13.2.6 Fiducials on Bars
13.2.7 Spatial Profiles
13.2.8 Line Spread Functions (Instrumental Profiles)
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 Wavelength Relationship
13.4 Apertures
52X0.05 Aperture
52X0.05E1 and 52X0.05D1 Pseudo-Apertures
52X0.1 Aperture
52X0.1E1and 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 Slits0.2X0.06FP(A-E) Apertures
FP-SPLIT Slits0.2X0.2FP(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
13.7.1 Recommendations for Stellar Observations with Narrow Slits
13.7.2 Order Overlap and Scattered Light for Echelle Gratings
13.7.3 Spectroscopic Mode Peculiarities
13.7.4 Railroad Tracks
13.8 MAMA Spectroscopic Bright Object Limits
Chapter 14: ImagingReference Material
14.1 Introduction
14.2 Using the Information in this Chapter
14.2.1 Sensitivity Units and Conversions
14.2.2 Signal-To-Noise
14.2.3 Point Spread Functions
14.3 CCD
CCD Clear Imaging—50CCD
CCD Long-Pass Imaging F28X50LP
F25QTZ—NUV-MAMA, Longpass
F25SRF2—NUV-MAMA, Longpass
25MAMAD1—FUV-MAMA Pseudo-Aperture
F25QTZ—FUV-MAMA, Longpass
F25QTZD1—FUV-MAMA, Longpass Pseudo-Aperture
F25SRF2—FUV-MAMA, Longpass
F25SRF2D1—FUV-MAMA, Longpass Pseudo-Aperture
F25LYA—FUV-MAMA, Lyman-α
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 Statusand Plans
17.1 Introduction
17.2 Ground Testing and Calibration
17.3 SMOV2 Testing and Calibration
17.4 Cycle 7 Calibration
17.4.1 Calibration Priorities
17.4.2 Calibration Status
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
Appendix A: Available-But-Unsupported Spectroscopic Capabilities
A.1 Introduction
A.2 Full Aperture Complement

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