|  
Acronym  | 
 Definition  | 
|   
AAVSO  | 
 American Association of Variable Stars Observers  | 
|  
AE    | 
 Analog Electronics  | 
|  
AO  | 
 Announcement of Opportunity  | 
|   
AGN  | 
 Active Galactic Nuclei  | 
|  
ARF   | 
   Ancillary  Response  File  | 
|   
ARK   | 
   Astrophysics Research Knowledgebase  | 
|  
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  | 
|  
CI  | 
 Charge Ingestion  | 
|  
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  |