The following table lists acronyms used in this document.
| Acronym | Definition |
| AAVSO | American Association of Variable Stars Observers |
| AE | Analog Electronics |
| AO | Announcement of Opportunity |
| AGN | Active Galactic Nuclei |
| ARF | Ancillary Response File |
| ASCA | Advanced Satellite for Cosmology and Astrophysics |
| ASM | All-Sky Monitor (on RXTE) |
| BGD | Background |
| BGO | Bismuth Germanate |
| BI | Back-Illuminated |
| CALDB | Calibration Database |
| CCD | Charge-Coupled Device |
| Co-I | Co-investigator |
| CPU | Central Processing Unit |
| CTE | Charge Transfer Efficiency |
| CTI | Charge Transfer Inefficiency |
| CXB | Cosmic X-ray Background |
| DDT | Director Discretionary Time |
| DE | Digital Electronics |
| Dec | Declination |
| DP | Data Processor |
| DSN | Deep Space Network |
| EA | Effective Area |
| EEF | Encircled Energy Function |
| EOB | Extensible Optical Bench |
| EPIC | European Photon Imaging Camera (on XMM-Newton) |
| ESA | European Space Agency |
| FI | Front-Illuminated |
| FWHM | Full-Width Half-Maximum |
| FITS | Flexible Image Transport System |
| FOV | Field Of View |
| FSA | Frame Store Area |
| FTOOLS | FITS Tools |
| Acronym | Definition |
| GO | Guest Observer |
| GOF | Guest Observer Facility |
| GRB | Gamma-Ray Burst |
| GSFC | Goddard Space Flight Center |
| GSO | Gadolinium Silicate |
| HEASARC | High Energy Astrophysics Science Archive Research Center |
| HESS | High Energy Stereoscopic System |
| HETG | High Energy Transmission Grating (on Chandra) |
| HEXTE | High Energy X-ray Timing Experiment (on RXTE) |
| HPD | Half-Power Diameter |
| HRI | High Resolution Imager (on ROSAT) |
| HV | High Voltage |
| HXD | Hard X-Ray Detector |
| ISAS | Institute of Space and Astronautical Science |
| INTEGRAL | INTErnational Gamma-Ray Astrophysics Laboratory |
| JAXA | Japan Aerospace Exploration Agency |
| LETG | Low Energy Transmission Grating (on Chandra) |
| LSI | Large Scale Integration |
| MIT | Massachusetts Institute of Technology |
| MPU | Main Processing Unit |
| NRA | NASA Research Announcement |
| NASA | National Aeronautics and Space Administration |
| NOI | Notice Of Intent |
| NSPIRES | NASA Solicitation and Proposal Integrated Review and Evaluation System |
| NXB | Non-X-ray Background |
| OBF | Optical Blocking Filter |
| PDS | Phoswich Detector System (on Bepppo-SAX) |
| PH | Pulse Height |
| PIN | Positive Intrinsic Negative |
| PI | Principal Investigator |
| PI | Pulse Invariant |
| PIMMS | Portable Interactive Multi-Mission Simulator |
| PM | Photo-Multiplier |
| PPU | Pixel Processing Unit |
| PSF | Point Spread Function |
| PSPC | Position-Sensitive Proportional Counter (on ROSAT) |
| P-Sum | Parallel-Sum |
| QDE | Quantum Detection Efficiency |
| RA | Right Ascension |
| RAM | Random Access Memory |
| RDD | Residual Dark-current Distribution |
| RGS | Reflection Grating Spectrometer (on XMM-Newton) |
| RFA | Research Focus Area |
| RMF | Redistribution Matrix File |
| ROSAT | RÖntgen SATellite |
| RPS | Remote Proposal Submission |
| RXTE | Rossi X-ray Timing Explorer |
| SAA | South Atlantic Anomaly |
| Acronym | Definition |
| SAX | Satellite per Astronomia X |
| S/C | Spacecraft |
| SGR | Soft Gamma-ray Repeater |
| SLAC | Stanford Linear Accelerator Center |
| SMC | Small Magellanic Cloud |
| SN | SuperNova |
| SWG | Science Working Group |
| TBD | To Be Determined |
| TCE | TEC Control Electronics |
| TCU | Thermal Control Unit |
| TEC | Thermo-Electric Cooler |
| TOO | Target Of Opportunity |
| US | United States |
| USC | Uchinoura Space Center |
| UV | Ultra Violet |
| VHS | Very High State |
| VSNET | Variable Star NETwork |
| WAM | Wide-band All-sky Monitor |
| XIS | X-Ray Imaging Spectrometer |
| XRB | X-ray Binary |
| XRS | X-Ray Spectrometer |
| XRT | X-Ray Telescope |
| XRT-I | X-Ray Telescope for one of the four XIS detectors |