This list is a superset of acronyms  and abbreviations used in this
document.
 - 2MASS
-      2 Micron All-Sky Survey
- ACA
-       Aspect Camera Assembly
- ACIS
-      Advanced CCD Imaging Spectrometer
- ACIS-I
-    ACIS Imaging array
- ACIS-S
-    ACIS Spectroscopic array
- ADU
-       Analog-to-Digital Unit
- AGASC
-     AXAF Guide and Aspect Star Catalog
- AGN
-        Active Galactic Nucleus or Nuclei
- ARF
- 	Ancillary Response File
- ASC
-       AXAF Science Center
- ASCA
-       Advanced Satellite for Cosmology and Astrophysics
- AXAF
-      Advanced X-Ray Astrophysics Facility
- BI
-        Back-illuminated
- CALDB
-     Calibration Data Base
- CAP
-       Central Aperture Plate
- CC
-        Continuous Clocking
- CCD
-       Charge Coupled Device
- CCDM
-      Communication, Command, and Data Management
- CCT
-        Chandra Cool Targets
- CDO
- 	CXC Director's Office
- CfP
- 	Call for Proposals
- CGCD
-      Crossed Grid Charge Detector
- CGRO
-    Compton Gamma-Ray Observatory
- CHaRT
- 	Chandra Ray Tracer
- CIAO
-    	Chandra Interactive Analysis of Observations
- COLDEN
-    Calculate Neutral Hydrogen Column Density
- COUP
-        Chandra Orion Ultradeep Project
- CPS
-        Chandra Proposal System or Chandra Proposal Software
- CSS
-       Coarse Sun Sensor
- CTI
-       Charge Transfer Inefficiency
- CXC
- 	Chandra X-ray Center
- CXCDS
- 	Chandra X-ray Center Data Systems
- CXO
- 	Chandra X-ray Observatory
- DEA
- 	Detector Electronics Assembly
- DPA
-        Digital Processing Assembly
- DSN
-       Deep Space Network
- EA
-        Effective Area
- ECS
-    External Calibration Source
- EDT
-       Eastern Daylight Time
- EPHIN
-     Electron Proton Helium Instrument
- ESA
-       Earth Sensor Assembly
- ESC
- 	Engineering Support Center
- EUV
-        Extreme Ultraviolet
- EXOSAT
-     European X-ray Observatory Satellite
- FI
-        Front-Illuminated
- FITS
-      Flexible Image Transport System
- FLA
-       Fiducial Light Assemblies
- FOT
- 	Flight Operations Team
- FOV
-       Field of View
- FP
-        Focal Plane
- FPC
-        Flow Proportional Counter
- FSS
-       Fine Sun Sensor
- FTS
-       Fiducial Transfer System
- FUV
-       Far-UV
- FWHM
-      Full Width at Half Maximum
- GESS
-      Grating Element Support Structure
- GO
-        General Observer
- GSFC
-      Goddard Space Flight Center
- GTO
-       Guaranteed Time Observer
- HEASARC
-   High Energy Astrophysics Science Archive Research Center
- HEG
-       High Energy Grating
- HESS
-      HETG Support Structure
- HETG
-      High Energy Transmission Grating
- HETGS
-     HETG Spectrometer
- HPD
-       Half Power Diameter
- HRC
-       High Resolution Camera
- HRC-I
-     HRC Imaging Detector
- HRC-S
-     HRC Spectroscopic Detector
- HRI
-       High Resolution Imager
- HRMA
-      High Resolution Mirror Assembly
- HXDS
-        HRMA X-ray Detection System
- IDL
-        Interactive Data Language
- IPI
-       Instrument Principal Investigator
- IPS
-       Integral Propulsion System
- IRU
-       Inertial Reference Unit
- ISIS
- 	Interactive Spectral Interpretation System
- ISM
-        Interstellar Medium
- IUS
-       Inertial Upper Stage
- JPL
-       Jet Propulsion Laboratory
- LESF
-      Low-energy Suppression Filter
- LETG
-      Low Energy Transmission Grating
- LETGS
-     LETG Spectrometer
- LMXB
-      Low-Mass X-ray Binary
- LRF
-       Line Response Function
- LSF
-       Line Spread Function
- LTS
- 	Long Term Schedule
- MARX
-      Model of AXAF Response to X-rays
- MCP
-       Micro Channel Plate
- MEG
-       Medium Energy Grating
- MIT
-       Massachusetts Institute of Technology
- MPE
-       Max-Planck-Institut für Extraterrestrische Physik
- MSC
-        Mirror Shell Coordinates
- MSFC
-      Marshall Space Flight Center
- MTA
-       Monitoring and Trends Analysis
- MUPS
-      Momentum Unloading Propulsion System
- NASA
-      National Aeronautics and Space Administration
- NASCOM
-    NASA Communication system
- NGAS
-        Northrop Grumman Aerospace Systems
- NMM
-       Normal Maneuver Mode
- NPM
-       Normal Pointing Mode
- OAC
-       Orbital Activation and Checkout
- OBA
-       Optical Bench Assembly
- OBC
-       On-Board Computer
- OBF
-       Optical Blocking Filter
- OBSCAT
-    Observation Catalog
- OBSVIS
-    Observation Visualizer
- OCC
-       Operations Control Center
- ODB
-       Optical Data Base
- OFLS
-      Off-line System
- ONLS
-      On-line System
- OR
- 	Observation Request
- OSIP
-        Order Sorting Integrated Probability
- PCA
-        Principal Component Analysis
- PCAD
-      Pointing Control and Aspect Determination
- PDA
-        Permanent Default Aimpoint
- PDF
- 	Portable Document Format
- PHA
-       Pulse Height Amplifier (or Amplitude)
- PI
-        Principal Investigator
- PIMMS
-     Portable Interactive Multi-Mission Software
- PRoVis
-    Pitch, Roll and Visibility tool
- PSF
-       Point Spread Function
- PSMC
- 	Power Supply and Mechanism Controller (for ACIS)
- QE
-        Quantum Efficiency
- QEU
-        Quantum Efficiency Uniformity
- RCS
-       Reaction Control System
- RCTU
-      Remote Command and Telemetry Unit
- RMF
- 	Redistribution Matrix File
- RMS
- 	Root Mean Squared
- ROSAT
-     Roentgen Satellite
- RRC
-       Retroreflector Collimator
- RWA
-       Reaction Wheel Assembly
- SADA
- 	Solar Array Drive Assembly
- SAO
-       Smithsonian Astrophysical Observatory
- SI
-        Science Instrument
- SIM
-       Science Instrument Module
- SKIRU
-     Space-Qualified Kearfott Inertial Reference Unit
- SMF
-       Software Maintenance Facility
- S/N
-        Signal-to-Noise ratio
- SNR
-       Supernova Remnant
- SOHO
-      Solar and Heliospheric Observatory
- SPIE
-        Society of Photo-Optical Instrumentation Engineers
- SRON
-        Laboratory for Space Research
- SSD
-       Solid-State Detector
- STS
- 	Short Term Schedule
- TE
-        Timed Exposure
- TOO
-       Target of Opportunity
- UTC
-       Coordinated Universal Time
- UV
-        Ultraviolet
- UVIS
-      UV/Ion Shield
- VCDU
-      Virtual Channel Data Unit
- VETA
-      Validation Engineering Test Article (mirror)
- VF
-        Very Faint
- XMM
-       X-ray Multi-Mirror Mission
- XRCF
-      X-ray Calibration Facility
- XSPEC
-     X-ray Spectral fitting package