Glossary

The following terms and acronyms are used in this Handbook.

ADU	Analog-to-digital Unit
ADC	Analog-to-digital Converter
ABMAG	–2.5 log (F_ν) – 48.60 where F_ν is the flux from the source in erg cm^–2 sec^-1 Hz^-1
AB_ν	Correction to ABMAG to account for the fact that the source spectrum is not constant in F_ν (ABMAG=V+AB_ν)
ACS	Advanced Camera for Surveys
APT	Astronomer’s Proposal Tool
`aXe`	Spectroscopic data extraction software (deprecated and replaced by `hstaxe`)
BOP	Bright Object Protection
`calwf3`	WFC3 calibration pipeline software
CCD	Charge Coupled Device; a solid-state, photon counting device
CDS	Correlated Double Sampling
COS	Cosmic Origins Spectrograph
CfP	Call for Proposals
CR	Cosmic ray
CR-SPLIT	Division of a CCD exposure into shorter exposures to be used for cosmic ray rejection
CSM	Channel select mechanism
CTE	Charge Transfer Efficiency
CVZ	Continuous Viewing Zone
DCL	Detector Characterization Laboratory at NASA/GSFC
DN	Data Number
DQ	Data Quality
EE	Encircled energy
ETC	Exposure Time Calculator; ETCs are Web-based tools which can be accessed through the WFC3 ETC webpage
FET	Field-effect Transistor
FGS	Fine Guidance Sensors
FITS	Flexible Image Transport System, the standardized astronomical data format (see NASA/GSFC documentation)
FOV	Field of View
FPA	Focal-Plane Array
FSM	Filter select mechanism
FWHM	Full width at half maximum
GO	General Observer
GSC	Guide Star Catalog
GSFC	NASA’s Goddard Space Flight Center
Help Desk	Facility for getting help on HST related topics: http://hsthelp.stsci.edu or help@stsci.edu
HRC	High Resolution Channel of ACS (non-operational)
HST	Hubble Space Telescope
`hstaxe`	Grism exposure analysis software (replaced `aXe`)
IPT	Integrated Product Team
IR	Infrared
IRAF	Image Reduction and Analysis System, the environment in which STSDAS operated; deprecated in 2018 (see article in STScI Newsletter Volume 35, Issue 03)
ISR	Instrument Science Report
K	Degree Kelvin
MAST	Barbara A. Mikulski Archive for Space Telescopes, an online-accessible data archive hosting data from missions including HST
MBE	Molecular-beam Epitaxial
MPP	Multi Pinned Phased, a CCD mode that reduces dark current rate.
MTF	Modulation Transfer Function
MUX	Multiplexer
NICMOS	Near-Infrared Camera and Multi-Object Spectrograph
NUV	Near ultraviolet (~2000–4000 Å)
OTA	Optical Telescope Assembly
PASP	Publications of the Astronomical Society of the Pacific
Phase `I`	A proposal for observing time on HST.
Phase `II`	An approved HST proposal; includes precise detail of how program is to be executed
PI	Principal investigator
POM	Pick-off Mirror
PRF	Pixel Response Function
PSF	Point-spread function
PyRAF	IRAF version implemented in the Python language; deprecated as of 2018 (see note in IRAF entry)
QE	Quantum efficiency
ramp	A sequence of non-destructive readouts comprising a single IR exposure
rms	Root mean square
SAA	South Atlantic anomaly
SBC	Solar-Blind Channel of ACS
SDSS	Sloan Digital Sky Survey
SED	Spectral-energy Distribution
SIAF	Science Instrument Aperture File
SM4	Servicing Mission 4
SMOV	Servicing Mission Observatory Verification
SNR	Signal-to-noise ratio
SOFA	Selectable Optical Filter Assembly
SOC	Scientific Oversight Committee
*ST-ECF*	Space Telescope European Coordinating Facility
STIS	Space Telescope Imaging Spectrograph
STScI	Space Telescope Science Institute
STSDAS	Space Telescope Science Data Analysis System, IRAF software for data analysis and calibration formerly used to process HST data; unsupported as of 2018 (see note in IRAF entry)
`stsynphot`	HST-specific synthetic photometry software package (designed to complement `synphot`); see `stsynphot` User's Guide, Lim et al. (2016)
`synphot`	Synthetic photometry software package; see `synphot` User's Guide, Lim et al. (2016)
TAC	Telescope Allocation Committee
TEC	Thermal Electric Coolers
TV	Thermal Vacuum (ground tests done before WFC3 was installed on HST)
UV	Ultraviolet
UVIS	Ultraviolet and Visual (CCD channel of WFC3)
*WFC*	Wide-Field Channel of ACS
WFC3	Wide Field Camera 3
WF/PC-1	Wide Field Planetary Camera-1. Original on-axis HST camera
WFPC2	Wide Field Planetary Camera-2. Replacement for WF/PC installed during first servicing mission of December 1993

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WFC3 Instrument Handbook
- • Acknowledgments
- Chapter 1: Introduction to WFC3
  - • 1.1 New for Cycle 31
  - • 1.2. Overview
  - • 1.3 Key Features of WFC3
  - • 1.4 WFC3 Quick Reference Guide
  - • 1.5 Special Considerations for Cycle 31
  - • 1.6 Sources of Further Information
  - • 1.7 The WFC3 Instrument Team at STScI
- Chapter 2: WFC3 Instrument Description
- Chapter 3: Choosing the Optimum HST Instrument
- Chapter 4: Designing a Phase I WFC3 Proposal
  - • 4.1 Phase I and Phase II Proposals
  - • 4.2 Preparing a Phase I Proposal
- Chapter 5: WFC3 Detector Characteristics and Performance
- Chapter 6: UVIS Imaging with WFC3
  - • 6.1 WFC3 UVIS Imaging
  - • 6.2 Specifying a UVIS Observation
  - • 6.3 UVIS Channel Characteristics
  - • 6.4 UVIS Field Geometry
  - • 6.5 UVIS Spectral Elements
  - • 6.6 UVIS Optical Performance
  - • 6.7 UVIS Exposure and Readout
  - • 6.8 UVIS Sensitivity
  - • 6.9 Charge Transfer Efficiency
  - • 6.10 Other Considerations for UVIS Imaging
  - • 6.11 UVIS Observing Strategies
- Chapter 7: IR Imaging with WFC3
  - • 7.1 WFC3 IR Imaging
  - • 7.2 Specifying an IR Observation
  - • 7.3 IR Channel Characteristics
  - • 7.4 IR Field Geometry
  - • 7.5 IR Spectral Elements
  - • 7.6 IR Optical Performance
  - • 7.7 IR Exposure and Readout
  - • 7.8 IR Sensitivity
  - • 7.9 Other Considerations for IR Imaging
  - • 7.10 IR Observing Strategies
- Chapter 8: Slitless Spectroscopy with WFC3
- Chapter 9: WFC3 Exposure-Time Calculation
  - • 9.1 Overview
  - • 9.2 The WFC3 Exposure Time Calculator - ETC
  - • 9.3 Calculating Sensitivities from Tabulated Data
  - • 9.4 Count Rates: Imaging
  - • 9.5 Count Rates: Slitless Spectroscopy
  - • 9.6 Estimating Exposure Times
  - • 9.7 Sky Background
  - • 9.8 Interstellar Extinction
  - • 9.9 Exposure-Time Calculation Examples
- Chapter 10: Overheads and Orbit Time Determinations
  - • 10.1 Overview
  - • 10.2 Observatory Overheads
  - • 10.3 Instrument Overheads
  - • 10.4 Orbit Use Examples
- Appendix A: WFC3 Filter Throughputs
  - • A.1 Introduction
  - A.2 Throughputs and Signal-to-Noise Ratio Data
    - • UVIS F200LP
    - • UVIS F218W
    - • UVIS F225W
    - • UVIS F275W
    - • UVIS F280N
    - • UVIS F300X
    - • UVIS F336W
    - • UVIS F343N
    - • UVIS F350LP
    - • UVIS F373N
    - • UVIS F390M
    - • UVIS F390W
    - • UVIS F395N
    - • UVIS F410M
    - • UVIS F438W
    - • UVIS F467M
    - • UVIS F469N
    - • UVIS F475W
    - • UVIS F475X
    - • UVIS F487N
    - • UVIS F502N
    - • UVIS F547M
    - • UVIS F555W
    - • UVIS F600LP
    - • UVIS F606W
    - • UVIS F621M
    - • UVIS F625W
    - • UVIS F631N
    - • UVIS F645N
    - • UVIS F656N
    - • UVIS F657N
    - • UVIS F658N
    - • UVIS F665N
    - • UVIS F673N
    - • UVIS F680N
    - • UVIS F689M
    - • UVIS F763M
    - • UVIS F775W
    - • UVIS F814W
    - • UVIS F845M
    - • UVIS F850LP
    - • UVIS F953N
    - • UVIS FQ232N
    - • UVIS FQ243N
    - • UVIS FQ378N
    - • UVIS FQ387N
    - • UVIS FQ422M
    - • UVIS FQ436N
    - • UVIS FQ437N
    - • UVIS FQ492N
    - • UVIS FQ508N
    - • UVIS FQ575N
    - • UVIS FQ619N
    - • UVIS FQ634N
    - • UVIS FQ672N
    - • UVIS FQ674N
    - • UVIS FQ727N
    - • UVIS FQ750N
    - • UVIS FQ889N
    - • UVIS FQ906N
    - • UVIS FQ924N
    - • UVIS FQ937N
    - • IR F098M
    - • IR F105W
    - • IR F110W
    - • IR F125W
    - • IR F126N
    - • IR F127M
    - • IR F128N
    - • IR F130N
    - • IR F132N
    - • IR F139M
    - • IR F140W
    - • IR F153M
    - • IR F160W
    - • IR F164N
    - • IR F167N
- Appendix B: Geometric Distortion
  - • B.1 Overview
  - • B.2 UVIS Channel
  - • B.3 IR Channel
- Appendix C: Dithering and Mosaicking
  - • C.1 Why Mosaicking and Dithering are Needed
  - • C.2 WFC3 Patterns
- Appendix D: Bright-Object Constraints and Image Persistence
  - • D.1 UVIS Channel
  - • D.2 IR Channel
- Appendix E: Reduction and Calibration of WFC3 Data
- • Glossary

Glossary

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