Table of Contents Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 20 Acknowledgments 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 20 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 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 4.2 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 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 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 with Large Extinction (Sk –69° 215) 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 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 FUV First-Order Spectral Offset to Avoid Repeller Wire 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 Long-Slit Spectroscopy 12.8 Parallel Observing with STIS 12.8.1 Coordinated Parallels: Using STIS in Parallel with Other Instruments 12.9 Coronagraphic Spectroscopy 12.10 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) 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 52X0.1E1and 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 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 F28X50OIII—CCD F28X50OII—CCD 50CORON—Clear CCD 14.26 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 14.70 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-α 14.99 Image Mode Geometric Distortion 14.100 Spatial Dependence of the STIS PSF 14.101 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 Appendix A: Available-But-Unsupported Spectroscopic Capabilities A.1 Introduction A.2 Full Aperture Complement A.3 Central Wavelength Settings Glossary
