Space Telescope Science Institute
STIS Instrument Handbook
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Table of Contents

Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 22
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 22
2.1 STIS Repair and Return to Operations
2.2 Summary of STIS Performance Changes Since 2004
2.3 Use of Available-but-Unsupported Capabilities
2.4 Should I Use COS or STIS?
2.5 Scheduling Efficiency and Visit Orbit Limits
2.6 MAMA Scheduling Policies
2.7 Prime and Parallel Observing: MAMA Bright Object Constraints
2.8 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
Slit and Grating Wheels
Calibration Lamp Systems
3.3 Basic Instrument Operations
Target Acquisitions and Peakups
Target Acquisitions and Peakups
Routine Wavecals
Data Storage and Transfer
Parallel Operations
3.3.1 Typical STIS Observing Sequence
3.4 Designing STIS Observations
3.4.1 Identify Science Requirements and Define STIS Configuration
Special Uses
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
4.2 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
E1 Aperture Positions to Decrease CTE Loss
E2 Aperture Positions for Better Fringe Flats
D1 Aperture Positions for Low FUV Dark Current
Sensitivity Differences at the 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
Limiting Magnitudes
5.1.3 Signal-To-Noise Ratios
5.1.4 Saturation
5.2 Optical CCD Imaging
Effect of the Optical Baffles on STIS CCD Imaging
5.2.1 Unfiltered (Clear) CCD Imaging: 50CCD & 50CORON
5.2.2 Optical Longpass: F28X50LP
5.2.3 [O III]: F28X50OIII
5.2.4 [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
2700 Continuum: F25CN270
1800 Continuum: F25CN182
Lyman Alpha: F25LYA and Clear-Minus-SRF2
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
Sensitivity Units and Conversions
Point Source
Diffuse Source
6.2.2 Imaging
Sensitivity Units and Conversions
Point Source
Diffuse Source
6.3 Throughput and Sensitivity
6.4 Computing Exposure Times
6.4.1 Calculating Exposure Times for a Given Signal-to-Noise
Special Case: Spectroscopic CCD Observations at λ < 2500
6.5 Detector and Sky Backgrounds
6.5.1 Detector Backgrounds
6.5.2 Sky Background
Background Variations and LOW-SKY
Geocoronal Emission and Shadow
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
G750L and G430L
6.8.3 Extended Source with Flux in cgs Units (NGC 6543): Imaging and Spectroscopy
Diffuse Source Spectroscopy in the Visible and Ultraviolet Regions
Visible Region
Ultraviolet Region
6.8.4 Echelle Spectroscopy of a Bright Star with Large Extinction (Sk –69 215)
Dereddened Magnitude and Prediction of 2500 Flux
Exposure Time Calculation
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
Changes in CCD Read Noise
Increasing Effects of Radiation Damage
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 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
NUV-MAMA Dark Current Before SM4
NUV-MAMA Dark Current after SM4
FUV-MAMA Dark Current
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
Pointings Close To Objects Violating Safety Limits
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
Jupiter and Saturn
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
Point Source Acquisition
Diffuse Acquisition
8.2.3 Selecting Target Acquisition Parameters
Selecting the Acquisition Object
Selecting the Acquisition Type
Selecting the Imaging Aperture
Determining Exposure Time for the ACQ Exposure
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
Selecting the Optical Element
Selecting the Aperture
Determining the Peakup Exposure Time
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?
Contents of ACQ and ACQ/PEAK image files
Target Acquisition Simulator
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
CCD Subarrays
11.1.2 MAMA ACCUM Mode
11.1.3 MAMA TIME-TAG Mode
Event Processing in TIME-TAG Mode
Buffer Management in TIME-TAG Mode
11.2 Exposure Sequences and Contemporaneous Calibrations
11.2.1 Auto-Wavecals
GO Wavecals
11.2.2 CR-SPLIT
11.2.3 Fringe Flat Fields
Designing Your Fringe Flat-Field Observations
Inserting Fringe Flat-Field Exposures in Phase II
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
Obtaining the Highest S/N Ratio with the FP-SPLIT Slits
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
Barred Spectroscopy
Specifying ORIENT with the 52X0.2F1 Aperture
Correcting Fringing for the 52X0.2F1 Aperture
12.11 Coronagraphic Imaging—50CORON
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)
How to Use The STMAGλ Tables
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
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
PSF Re-Imaging
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
STIS-01: Modes and Data Interface Checks
STIS-02: Memory Load and Dump
STIS-03: Science Data Buffer Check with Self-Test
STIS-04: Mechanism Mini-Functional
STIS-05: CCD Anneal
STIS-06: CCD Functional
STIS-07: CCD Bias and Dark Monitor
STIS-08: Aperture Wheel and Lamp Functional Tests
STIS-09: STIS to FGS Alignment
STIS-10: CCD Optical Format Verification
STIS-11: External Focus Check
STIS-12: Corrector and Focus Alignment
STIS-13: CCD Spectroscopic Image Quality and ACQ Tests
STIS-14: CCD CTE Check
STIS-15: CCD Spectroscopic Throughputs
STIS-16: CCD Image and Pointing Stability
STIS-17: FUV-MAMA HV Recovery
STIS-18: NUV-MAMA HV Recovery
STIS-19: FUV-MAMA Dark Measure
STIS-20: NUV Dark Monitor
STIS-21: FUV-MAMA Optical Format Verification
STIS-22: NUV-MAMA Optical Format Verification
STIS-23: FUV-MAMA Image Quality
STIS-24: NUV-MAMA Image Quality
STIS-25: MAMA Spectroscopic Throughputs
STIS-26: MAMA Image Stability
17.11 Cycle 17 Calibration Plan
17.12 Cycle 18 Calibration Plan
17.13 Cycle 19 Calibration Plan
Appendix A: Available-But-Unsupported Spectroscopic Capabilities
A.1 Introduction
A.2 Full Aperture Complement

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