Near Infrared Camera and Multi-Object Spectrometer Instrument Handbook for Cycle 17

Table of Contents

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Table of Contents

Acknowledgments

Chapter 1: Introduction and General Considerations

1.1 Purpose

Document Conventions

1.2 Layout

1.3 NICMOS Proposal Preparation

1.4 The Help Desk at STScI

1.5 The NICMOS Instrument Team at STScI

1.6 Supporting Information and the NICMOS Web Site

1.7 NICMOS History in Brief

1.8 Three-Gyro Guiding

1.9 Recommendations for Proposers

1.10 Supported and Unsupported NICMOS Capabilities

Chapter 2: Overview of NICMOS

2.1 Instrument Capabilities

2.2 Heating, Cooling and Focus

2.3 NICMOS Instrument Design

2.3.1 Physical Layout

2.3.2 Imaging Layout

2.3.3 Camera NIC1

2.3.4 Camera NIC2

2.3.5 Camera NIC3

2.3.6 Location and Orientation of Cameras

2.4 Basic Operations

2.4.1 Detectors' Characteristics and Operations

2.4.2 Comparison to CCDs

2.4.3 Target Acquisition Modes

2.4.4 Attached Parallels

Chapter 3: Designing NICMOS Observations

3.1 Overview of Design Process

3.2 APT and Aladin

Chapter 4: Imaging

4.1 Filters and Optical Elements

4.1.1 Nomenclature

4.1.2 Out-of-Band Leaks in NICMOS Filters

4.2 Photometry

4.2.1 Solar Analog Absolute Standards

4.2.2 White Dwarf Absolute Standards

4.2.3 Photometric Throughput and Stability

4.2.4 Count Rate Dependent Non-linearity

4.2.5 Intrapixel Sensitivity Variations

4.2.6 Special Situations

4.3 Focus History

4.4 Image Quality

4.4.1 Strehl Ratios

4.4.2 NIC1 and NIC2

4.4.3 NIC3

4.4.4 PSF Structure

4.4.5 Optical Aberrations: Coma and Astigmatism

4.4.6 Field Dependence of the PSF

4.4.7 Temporal Dependence of the PSF: HST Breathing and Cold Mask Shifts

4.5 Cosmic Rays

4.6 Photon and Cosmic Ray Persistence

4.7 The Infrared Background

4.8 The "Pedestal Effect"

Chapter 5: Coronagraphy, Polarimetry and Grism Spectroscopy

5.1 Coronagraphy

5.1.1 Coronagraphic Acquisitions

5.1.2 PSF Centering

5.1.3 Temporal Variations of the PSF

5.1.4 FGS Guiding

5.1.5 Cosmic Ray Persistence

5.1.6 Contemporary Flat Fields

5.1.7 Coronagraphic Polarimetry

5.1.8 Coronagraphic Decision Chart

5.2 Polarimetry

5.2.1 NIC 1 and NIC2 Polarimetric Characteristics and Sensitivity

5.2.2 Ghost images

5.2.3 Observing Strategy Considerations

5.2.4 Limiting Factors

5.2.5 Polarimetry Decision Chart

5.3 Grism Spectroscopy

5.3.1 Observing Strategy

5.3.2 Grism Calibration

5.3.3 Relationship Between Wavelength and Pixel

5.3.4 Sensitivity

5.3.5 Intrapixel Sensitivity

5.3.6 Grism Decision Chart

Chapter 6: NICMOS Apertures and Orientation

6.1 NICMOS Aperture Definitions

6.2 NICMOS Coordinate System Conventions

6.3 Orients

Chapter 7: NICMOS Detectors

7.1 Detector basics

7.2 Detector Characteristics

7.2.1 Overview

7.2.2 Dark Current

7.2.3 Flat Fields and the DQE

7.2.4 Read Noise

7.2.5 Linearity and Saturation

7.2.6 Count Rate Non-Linearity

7.3 Detector Artifacts

7.3.1 Shading

7.3.2 Amplifier Glow

7.3.3 Overexposure of NICMOS Detectors

7.3.4 Electronic Bars and Bands

7.3.5 Detector Cosmetics

7.3.6 "Grot"

Chapter 8: Detector Readout Modes

8.1 Introduction

Detector Resetting as a Shutter

8.2 Multiple-Accumulate Mode

8.3 MULTIACCUM Predefined Sample Sequences (SAMP-SEQ)

8.4 Accumulate Mode

8.5 Read Times and Dark Current Calibration in ACCUM Mode

8.6 Trade-offs Between MULTIACCUM and ACCUM

8.7 Acquisition Mode

Chapter 9: Exposure Time Calculations

9.1 Overview: Web based NICMOS APT-ETC

9.1.1 Instrumental Factors

9.2 Calculating NICMOS Imaging Sensitivities

9.2.1 Calculation of Signal-to-Noise Ratio

9.2.2 Saturation and Detector Limitations

9.2.3 Exposure Time Calculation

Chapter 10: Overheads and Orbit Time Determination

10.1 Overview

10.2 NICMOS Exposure Overheads

10.3 Orbit Use Determination

10.3.1 Observations in the Thermal Regime Using a Chop Pattern and MULTIACCUM

Appendix A: Imaging Reference Material

Appendix B: Flux Units and Line Lists

B.1 Infrared Flux Units

B.1.1 Some History

B.2 Formulae

B.2.1 Converting Between Fn and Fl

B.2.2 Conversion Between Fluxes and Magnitudes

B.2.3 Conversion Between Surface Brightness Units

B.3 Look-up Tables

B.4 Examples

B.5 Infrared Line Lists

Appendix C: Bright Object Mode

C.1 Bright Object Mode

Appendix D: Techniques for Dithering, Background Measurement and Mapping

D.1 Introduction

D.2 Strategies For Background Subtraction

D.2.1 Compact Objects

D.2.2 Extended Objects

D.3 Chopping and Dithering Patterns

D.3.1 Dither Patterns

D.3.2 Chop Patterns

D.3.3 Combined Patterns

D.3.4 Map Patterns

D.3.5 Combining Patterns and POS-TARGs

D.3.6 Generic Patterns

D.4 Examples

D.5 Types of Motions

Appendix E: The NICMOS Cooling System

E.1 The NICMOS Cooling System

Glossary and Acronym List

Index