Space Telescope Science Institute
STIS Instrument Handbook
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Table of Contents
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 Considerations for 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
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
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
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
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
13.4 Apertures
13.5 Spatial Profiles
13.6 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: Imaging Reference 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
14.4 NUV-MAMA
14.5 FUV-MAMA
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 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
Appendix A: Available-But-Unsupported
Spectroscopic Capabilities
A.1 Introduction
A.2 Full Aperture Complement
Glossary
Index

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