Frequently Seen Space/Astronomy Acronyms

From: (Mark Bradford)
Newsgroups: sci.astro,,,,sci.answers,news.answers
Subject: Astro/Space Frequently Seen Acronyms
Keywords: long space astro tla acronyms
Followup-To: poster
Organization: Surly Dinosaurs
Approved: news-answers-request@MIT.Edu

Archive-name: space/acronyms

Acronym List for Space and Astronomy
As of 2009 April 14

This list is offered as a reference for translating commonly appearing acronyms in the space-related newsgroups. If I forgot or botched your favorite acronym, please let me know! Also, if there's an acronym not on this list that confuses you, drop me a line, and if I can figure it out, I'll add it to the list.

The canonical version of this list is the HTML form, available at . From that, I generate the text form for USENET posting.

Note that this is intended to be a reference for frequently seen acronyms, and is most emphatically not encyclopedic. If I incorporated every acronym I ever saw, I'd soon run out of disk space. :-)

The list will be posted at regular intervals, every 30 days. All comments regarding it are welcome; I'm reachable at NOTE: Due to the high level of spam I receive, you must include the text "tla" in the Subject header of your e-mail, or I will never see your message.

Note that this list just tells what the acronyms stand for -- you're on your own for figuring out what they mean. Note also that the total number of acronyms in use far exceeds what I can list; special-purpose acronyms that are essentially always explained as they're introduced are omitted. Further, some acronyms stand for more than one thing; these acronyms appear on multiple lines.

Thanks to everybody who's sent suggestions since the first version of the list!

PS: Strictly speaking, most of these are "initialisms" or "abbreviations" rather than "acronyms"; pedantically, it's only an "acronym" if you make a word out of it, like "laser" or "radar." In practice, though, everybody calls 'em acronyms.

A&A:  Astronomy and Astrophysics
AAO:  Anglo-Australian Observatory
AAS:  American Astronomical Society
AAS:  American Astronautical Society
AAVSO:  American Association of Variable Star Observers
ACE:  Advanced Composition Explorer
ACRV:  Assured Crew Return Vehicle (or) Astronaut Crew Rescue Vehicle
AD:  Analog to Digital
ADFRF:  Ames-Dryden Flight Research Facility (now DFRC) (NASA)
AFAIK:  As Far As I Know
AGN:  Active Galactic Nucleus
AGU:  American Geophysical Union
AIAA:  American Institute of Aeronautics and Astronautics
AIPS:  Astronomical Image Processing System
AIT:  Assembly, Integration, and Testing
AJ:  Astronomical Journal
ALEXIS:  Array of Low Energy X-ray Imaging Sensors
ALPO:  Association of Lunar and Planetary Observers
ALS:  Advanced Launch System
ANSI:  American National Standards Institute
AOA:  Abort Once Around (Shuttle abort plan)
AOA:  Angle Of Attack
AOCS:  Attitude and Orbit Control System
Ap.J:  Astrophysical Journal
APL:  Applied Physics Laboratory (at Johns Hopkins)
APM:  Attached Pressurized Module (a.k.a. Columbus)
APU:  Auxiliary Power Unit
ARC:  Ames Research Center (NASA)
ARC:  Astrophysical Research Consortium
ARTEMIS:  Advanced Relay TEchnology MISsion
ASA:  Astronomical Society of the Atlantic
ASC:  Agence Spatiale Canadienne (also CSA)
ASI:  Agenzia Spaziale Italiana
ASP:  Astronomical Society of the Pacific
ASRM:  Advanced Solid Rocket Motor
ATDRS:  Advanced Tracking and Data Relay Satellite
ATLAS:  Atmospheric Laboratory for Applications and Science
ATM:  Amateur Telescope Maker
ATM:  Apollo Telescope Mount (on Skylab)
ATO:  Abort To Orbit
ATV:  Automated Transfer Vehicle
AU:  Astronomical Unit
AURA:  Association of Universities for Research in Astronomy
AW&ST:  Aviation Week and Space Technology (a.k.a. AvLeak)
AXAF:  Advanced X-ray Astrophysics Facility
BAe:  British Aerospace (now BAE SYSTEMS)
BATSE:  Burst And Transient Source Experiment (on CGRO)
BBXRT:  Broad-Band X-Ray Telescope (ASTRO package)
BDB:  Big Dumb Booster
BEM:  Bug-Eyed Monster
BH:  Black Hole
BIMA:  Berkeley Illinois Maryland Array
BIS:  British Interplanetary Society
BMDO:  Ballistic Missile Defense Office (was SDIO)
BNSC:  British National Space Centre
BTW:  By The Way
CARA:  Center for Astrophysical Research in Antarctica
C&T:  Communications & Tracking
CATS:  Cheap Access To Space
CCAFS:  Cape Canaveral Air Force Station
CCAS:  Cape Canaveral Air Station (now once again CCAFS)
CCD:  Charge-Coupled Device
CCDS:  Centers for the Commercial Development of Space
CD-ROM:  Compact Disc Read-Only Memory
CFA:  Center For Astrophysics
CFC:  ChloroFluoroCarbon
CFF:  Columbus Free Flyer
CFHT:  Canada-France-Hawaii Telescope
CFIT:  Controlled Flight Into Terrain
CG:  Center of Gravity
CGRO:  (Arthur Holley) Compton Gamma Ray Observatory (was GRO)
CHARA:  Center for High Angular Resolution Astronomy
CIRRIS:  Cryogenic InfraRed Radiance Instrument for Shuttle
CIT:  Circumstellar Imaging Telescope
CM:  Command Module (Apollo spacecraft)
CM:  Center of Mass
CMBR:  Cosmic Microwave Background Radiation
CMCC:  Central Mission Control Centre (ESA)
CNES:  Centre National d'Etude Spatiales
CNO:  Carbon-Nitrogen-Oxygen
CNSR:  Comet Nucleus Sample Return
COBE:  COsmic Background Explorer
COMPTEL:  COMPton TELescope (on CGRO)
COSTAR:  Corrective Optics Space Telescope Axial Replacement
COTS:  Commercial (or Cheap) Off The Shelf
CRAF:  Comet Rendezvous / Asteroid Flyby
CRRES:  Combined Release / Radiation Effects Satellite
CSA:  Canadian Space Agency (also ASC)
CSM:  Command and Service Module (Apollo spacecraft)
CSTC:  Consolidated Space Test Center (USAF)
CTB:  Cargo Transfer Bag
CTIO:  Cerro Tololo Interamerican Observatory
CV:  Cataclysmic Variable
CXBR:  Cosmic X-ray Background Radiation
DC:  Delta Clipper
DCX:  Delta Clipper eXperimental
DDCU:  DC-to-DC Converter Unit
DDTE:  Design, Development, Test, and Evaluation
DFRC:  Dryden Flight Research Center
DFRF:  Dryden Flight Research Facility (was ADFRF, now DFRC)
DMSP:  Defense Meteorological Satellite Program
DOD:  Department Of Defense (sometimes DoD)
DOE:  Department Of Energy
DOT:  Department Of Transportation
DRS:  Data Relay Satellite
DRS:  Direct Receiving Station
DSO:  Deep Sky (or Space) Object
DSCS:  Defense Satellite Communications System
DSN:  Deep Space Network
DSP:  Defense Support Program (USAF/NRO)
EAC:  European Astronaut Centre
EAFB:  Edwards Air Force Base
ECS:  Environmental Control System
EDO:  Extended Duration Orbiter
EGRET:  Energetic Gamma Ray Experiment Telescope (on CGRO)
EJASA:  Electronic Journal of the Astronomical Society of the Atlantic
ELV:  Expendable Launch Vehicle
EMU:  Extravehicular Mobility Unit
EOS:  Earth Observing System
ER:  Eastern Range (was ETR)
ERS:  Earth Resources Satellite (as in ERS-1)
ESA:  European Space Agency
ESIS:  European Space Information System
ESO:  European Southern Observatory
ESOC:  European Space Operations Centre
ESTEC:  European Space Research & Technology Centre
ET:  (Shuttle) External Tank
ETLA:  Extended Three Letter Acronym
ETR:  Eastern Test Range
EUV:  Extreme UltraViolet
EUVE:  Extreme UltraViolet Explorer
EVA:  ExtraVehicular Activity
FAQ:  Frequently Asked Questions
FAST:  Fast Auroral SnapshoT explorer
FFT:  Fast Fourier Transform
FGS:  Fine Guidance Sensors (on HST)
FHST:  Fixed Head Star Trackers (on HST)
FIR:  Far InfraRed
FITS:  Flexible Image Transport System
FOC:  Faint Object Camera (on HST)
FOS:  Faint Object Spectrograph (on HST)
FOV:  Field Of View
FRC:  Flight Research Center (old name for DFRC)
FRR:  Flight-Readiness Review
FTETTM:  From The Earth To The Moon
FTL:  Faster Than Light
FTP:  File Transfer Protocol
FTS:  Flight Telerobotic Servicer
FUSE:  Far Ultraviolet Spectroscopic Explorer
FWHM:  Full Width at Half Maximum
FYI:  For Your Information
G:  Gravity
GAS:  Get-Away Special
GBT:  Green Bank Telescope
GCVS:  General Catalog of Variable Stars
GEM:  Giotto Extended Mission
GEM:  Galileo Europa Mission
GEO:  Geosynchronous Earth Orbit
GDS:  Great Dark Spot
GHRS:  Goddard High Resolution Spectrograph (on HST)
GIF:  Graphics Interchange Format
GLOMR:  Global Low-Orbiting Message Relay
GLOW:  Gross Lift-Off Weight
GMC:  Giant Molecular Cloud
GMRT:  Giant Meter-wave Radio Telescope
GMT:  Greenwich Mean Time (also called UT)
GOES:  Geostationary Orbiting Environmental Satellite
GOX:  Gaseous OXygen
GPC:  General Purpose Computer
GPS:  Global Positioning System
GR:  General Relativity
GRB:  Gamma Ray Burster
GRC:  Glenn Research Center (NASA)
GRO:  Gamma Ray Observatory (now CGRO)
GRS:  Gamma Ray Spectrometer (on Mars Observer)
GRS:  Great Red Spot
GSC:  Guide Star Catalog (for HST)
GSFC:  Goddard Space Flight Center (NASA)
GTO:  Geostationary Transfer Orbit
GVI:  Global Village Idiot
HAO:  High Altitude Observatory
HD:  Henry Draper catalog entry
HEAO:  High Energy Astronomical Observatory
HeRA:  Hermes Robotic Arm
HF:  High Frequency
HGA:  High Gain Antenna
HLC:  Heavy Lift Capability
HLV:  Heavy Lift Vehicle
HMC:  Halley Multicolor Camera (on Giotto)
HOTOL:  HOrizontal TakeOff and Landing (a proposed SSTO craft)
HR:  Hertzsprung-Russell (diagram)
HRMS:  High Resolution Microwave Survey
HRI:  High Resolution Imager (on ROSAT)
HSP:  High Speed Photometer (on HST)
HST:  Hubble Space Telescope
HTH:  Hope This Helps
HTHL:  Horizontal Takeoff Horizontal Landing
HTVL:  Horizontal Takeoff Vertical Landing
HUT:  Hopkins Ultraviolet Telescope (ASTRO package)
HV:  High Voltage
IAPPP:  International Amateur/Professional Photoelectric Photometry
IAU:  International Astronomical Union
IAUC:  IAU Circular
ICE:  International Cometary Explorer
IDA:  International Dark-sky Association
IDL:  Interactive Data Language
IGM:  InterGalactic Medium
IGY:  International Geophysical Year
IIRC:  If I Recall Correctly
IMHO:  In My Humble Opinion
IMO:  International Meteor Organization
INTEGRAL:  INTErnational Gamma-Ray Astrophysics Laboratory
IOTA:  Infrared-Optical Telescope Array
IOTA:  International Occultation Timing Association
IPS:  Inertial Pointing System
IR:  InfraRed
IRAF:  Image Reduction and Analysis Facility
IRAS:  InfraRed Astronomical Satellite
IRFNA:  Inhibited Red Fuming Nitric Acid
ISAS:  Institute of Space and Astronautical Science (Japan)
ISM:  InterStellar Medium
ISO:  Infrared Space Observatory
ISO:  International Standards Organization
ISPM:  International Solar Polar Mission (now Ulysses)
ISPP:  In-Situ Propellant Production
ISS:  International Space Station
ISY:  International Space Year
IUE:  International Ultraviolet Explorer
IUS:  Inertial Upper Stage
JEM:  Japanese Experiment Module (for SSF)
JGR:  Journal of Geophysical Research
JILA:  Joint Institute for Laboratory Astrophysics
JPL:  Jet Propulsion Laboratory
JSC:  Johnson Space Center (NASA)
KAO:  Kuiper Airborne Observatory
KPNO:  Kitt Peak National Observatory
KSC:  Kennedy Space Center (NASA)
KTB:  Cretaceous-Tertiary Boundary (from German)
L:  Lagrange (as in Lagrange points L1 through L5)
LANL:  Los Alamos National Laboratory
LaRC:  Langley Research Center (NASA)
LASER:  Light Amplification by Stimulated Emission of Radiation
LDEF:  Long Duration Exposure Facility
LEM:  Lunar Excursion Module (a.k.a. LM) (Apollo spacecraft)
LEO:  Low Earth Orbit
LeRC:  Lewis Research Center (NASA; now GRC)
LEST:  Large Earth-based Solar Telescope
LFSA:  List of Frequently Seen Acronyms (!)
LGA:  Low Gain Antenna
LGM:  Little Green Men
LH:  Liquid Hydrogen (also LH2 or LHX)
LITVC:  Liquid Injection Thrust Vector Control
LLNL:  Lawrence-Livermore National Laboratory
LM:  Lunar Module (a.k.a. LEM) (Apollo spacecraft)
LMC:  Large Magellanic Cloud
LN2:  Liquid N2 (Nitrogen)
LOX:  Liquid OXygen
LPO:  La Palma Observatory
LPV:  Long Period Variable
LRB:  Liquid Rocket Booster
LSR:  Local Standard of Rest
LTP:  Lunar Transient Phenomenon
M:  Messier (as in M31, M13, M57, etcetera)
MACRO:  Monopoles, Astrophysics, and Cosmic Ray Observatory
MB:  Manned Base
MCC:  Mission Control Center
MCD:  Minimum Cost Design
MCO:  Mars Climate Orbiter
MECO:  Main Engine CutOff
MERIS:  Medium Resolution Imaging Spectrometer
MGS:  Mars Global Surveyor
MHD:  MagnetoHydroDynamic
MLI:  Multi-Layer Insulation
MMH:  MonoMethyl Hydrazine
MMT:  Multiple Mirror Telescope
MMU:  Manned Maneuvering Unit
MNRAS:  Monthly Notices of the Royal Astronomical Society
MO:  Mars Observer
MOC:  Mars Observer Camera (on MO and MGS)
MODIS:  Moderate Resolution Imaging Spectroradiometer
MOL:  Manned Orbiting Laboratory
MOLA:  Mars Observer Laser Altimeter (on Mars Observer)
MOMV:  Manned Orbital Maneuvering Vehicle
MOTV:  Manned Orbital Transfer Vehicle
MPC:  Minor Planets Circular
MPEC:  Minor Planets Electronic Circular
MPL:  Mars Polar Lander
MRSR:  Mars Rover and Sample Return
MRSRM:  Mars Rover and Sample Return Mission
MSFC:  (George C.) Marshall Space Flight Center (NASA)
MTC:  Man Tended Capability
NACA:  National Advisory Committee on Aeronautics (became NASA)
NASA:  National Aeronautics and Space Administration
NASDA:  NAtional Space Development Agency (Japan)
NASM:  National Air and Space Museum
NASP:  National AeroSpace Plane
NBS:  National Bureau of Standards (now NIST)
NDV:  NASP Derived Vehicle
NEAR:  Near Earth Asteroid Rendezvous (now named NEAR Shoemaker)
NERVA:  Nuclear Engine for Rocket Vehicle Application
NG:  NewsGroup
NGC:  New General Catalog
NGST:  Next Generation Space Telescope
NICMOS:  Near Infrared Camera / Multi Object Spectrometer (HST upgrade)
NIMS:  Near-Infrared Mapping Spectrometer (on Galileo)
NIR:  Near InfraRed
NIST:  National Institute of Standards and Technology (was NBS)
NLDP:  National Launch Development Program
NOAA:  National Oceanic and Atmospheric Administration
NOAO:  National Optical Astronomy Observatories
NORAD:  NORth American aerospace Defense
NRAO:  National Radio Astronomy Observatory
NRO:  National Reconnaissance Office
NS:  Neutron Star
NSA:  National Security Agency
NSF:  National Science Foundation
NSO:  National Solar Observatory
NSSDC:  National Space Science Data Center
NTR:  Nuclear Thermal Rocket(ry)
NTT:  New Technology Telescope
OAO:  Orbiting Astronomical Observatory
OCST:  Office of Commercial Space Transportation
OMB:  Office of Management and Budget
OMS:  Orbital Maneuvering System
OPF:  Orbiter Processing Facility
ORFEUS:  Orbiting and Retrievable Far and Extreme Ultraviolet Spectrometer
OSC:  Orbital Sciences Corporation
OSCAR:  Orbiting Satellite Carrying Amateur Radio
OSSA:  Office of Space Science and Applications
OSSE:  Oriented Scintillation Spectrometer Experiment (on CGRO)
OT:  Off-Topic
OTA:  Optical Telescope Assembly (on HST)
OTHB:  Over The Horizon Backscatter
OTV:  Orbital Transfer Vehicle
OV:  Orbital Vehicle
PAM:  Payload Assist Module
PAM-D:  Payload Assist Module, Delta-class
PDS:  Planetary Data System
PI:  Principal Investigator
PLSS:  Portable Life Support System
PM:  Pressurized Module
PMC:  Permanently Manned Capability
PMIRR:  Pressure Modulated InfraRed Radiometer (on Mars Observer)
PMT:  PhotoMultiplier Tube
PPM:  Positions and Proper Motions (catalog)
PSF:  Point Spread Function
PSR:  PulSaR
PV:  Photovoltaic
PVO:  Pioneer Venus Orbiter
QSO:  Quasi-Stellar Object
RADAR:  RAdio Detection And Ranging
RAS:  Royal Astronomical Society
RASC:  Royal Astronomical Society of Canada
RCI:  Rodent Cage Interface (for SLS mission)
RCS:  Radar Cross Section
RCS:  Reaction Control System
REM:  Rat Enclosure Module (for SLS mission)
RF:  Radio Frequency
RFI:  Radio Frequency Interference
RFNA:  Red Fuming Nitric Acid
RIACS:  Research Institute for Advanced Computer Science
RMS:  Remote Manipulator System
RNGC:  Revised New General Catalog
ROTFL:  Rolling On The Floor Laughing
ROSAT:  ROentgen SATellite
ROUS:  Rodents Of Unusual Size (I don't believe they exist)
RSA:  Russian Space Agency
RSN:  Radio SuperNova
RSN:  Real Soon Now
RTG:  Radioisotope Thermoelectric Generator
RTLS:  Return To Launch Site (Shuttle abort plan)
SAA:  South Atlantic Anomaly
SAGA:  Solar Array Gain Augmentation (for HST)
SAMPEX:  Solar Anomalous and Magnetospheric Particle EXplorer
SAO:  Smithsonian Astrophysical Observatory
SAR:  Search And Rescue
SAR:  Synthetic Aperture Radar
SARA:  Satellite pour Astronomie Radio Amateur
SAREX:  Search and Rescue Exercise
SAREX:  Space Amateur Radio Experiment
SAS:  Space Activity Suit
SAS:  Space Adaptation Syndrome
SAT:  Synthetic Aperture Telescope
S/C:  SpaceCraft
SCA:  Shuttle Carrier Aircraft
SCT:  Schmidt-Cassegrain Telescope
SDI:  Strategic Defense Initiative
SDIO:  Strategic Defense Initiative Organization (now BMDO)
SEDS:  Students for the Exploration and Development of Space
SEI:  Space Exploration Initiative
SEST:  Swedish ESO Submillimeter Telescope
SETI:  Search for ExtraTerrestrial Intelligence
SID:  Sudden Ionospheric Disturbance
SIR:  Shuttle Imaging Radar
SIRTF:  Space (formerly Shuttle) InfraRed Telescope Facility
SL:  (Comet) Shoemaker-Levy
SL:  SpaceLab
SLAR:  Side-Looking Airborne Radar
SLC:  Space Launch Complex
SLS:  Space(lab) Life Sciences
SMC:  Small Magellanic Cloud
SME:  Solar Mesosphere Explorer
SMEX:  SMall EXplorers
SMM:  Solar Maximum Mission
SN:  SuperNova (e.g., SN1987A)
SNR:  Signal to Noise Ratio
SNR:  SuperNova Remnant
SNU:  Solar Neutrino Units
SOFIA:  Stratospheric Observatory For Infrared Astronomy
SOHO:  SOlar Heliospheric Observatory
SPAN:  Space Physics and Analysis Network
SPDM:  Special Purpose Dextrous Manipulator
SPOT:  Satellite Pour l'Observation de la Terre
SPS:  Solar Power Satellite
SR:  Special Relativity
SRB:  Solid Rocket Booster
SRM:  Solid Rocket Motor
SSF:  Space Station Fred (er, Freedom) (Superseded by ISS)
SSI:  Solid-State Imager (on Galileo)
SSI:  Space Studies Institut
SSME:  Space Shuttle Main Engine
SSPF:  Space Station Processing Facility
SSPS:  Sky Survey Prototype System
SSRMS:  Space Station Remote Manipulator System
SSRT:  Single Stage Rocket Technology
SST:  Spectroscopic Survey Telescope
SST:  SuperSonic Transport
SSTO:  Single Stage To Orbit
STIS:  Space Telescope Imaging Spectrometer (to replace FOC and GHRS)
STS:  Shuttle Transport System (or) Space Transportation System
STScI:  Space Telescope Science Institute
STSDAS:  Space Telescope Science Data Analysis System
SWAS:  Submillimeter Wave Astronomy Satellite
SWF:  ShortWave Fading
TAL:  Transatlantic Abort Landing (Shuttle abort plan)
TANSTAAFL:  There Ain't No Such Thing As A Free Lunch
TAU:  Thousand Astronomical Unit (mission)
TCS:  Thermal Control System
TDRS:  Tracking and Data Relay Satellite
TDRSS:  Tracking and Data Relay Satellite System
TEA:  Torque Equilibrium Attitude
TES:  Thermal Emission Spectrometer (on Mars Observer)
THEMIS:  THermal EMission Imaging System (on Mars 2001 Odyssey)
TIROS:  Television InfraRed Observation Satellite
TLA:  Three Letter Acronym
TOMS:  Total Ozone Mapping Spectrometer
TOPS:  Toward Other Planetary Systems
TPS:  Thermal Protection System
TSS:  Targeted Search System
TSS:  Tethered Satellite System
TSTO:  Two Stage To Orbit (also 2STO)
UARS:  Upper Atmosphere Research Satellite
UBM:  Unpressurized Berthing Mechanism
UDMH:  Unsymmetrical DiMethyl Hydrazine
UFO:  Unidentified Flying Object
UGC:  Uppsala General Catalog
UHF:  Ultra High Frequency
UIT:  Ultraviolet Imaging Telescope (Astro package)
UKST:  United Kingdom Schmidt Telescope
USAF:  United States Air Force
USMP:  United States Microgravity Payload
USNO:  United States Naval Observatory
UT:  Universal Time (a.k.a. GMT, or Zulu Time; cf UTC)
UTC:  Coordinated Universal Time (subtly different from UT)
UV:  UltraViolet
UVS:  UltraViolet Spectrometer
VAB:  Vehicle Assembly Building (formerly Vertical Assembly Building)
VAFB:  Vandenberg Air Force Base
VEEGA:  Venus-Earth-Earth Gravity Assist (Galileo flight path)
VHF:  Very High Frequency
VLA:  Very Large Array
VLBA:  Very Long Baseline Array
VLBI:  Very Long Baseline Interferometry
VLF:  Very Low Frequency
VLT:  Very Large Telescope
VMS:  Vertical Motion Simulator
VOIR:  Venus Orbiting Imaging Radar (superseded by VRM)
VPF:  Vertical Processing Facility
VRM:  Venus Radar Mapper (now called Magellan)
VTHL:  Vertical Takeoff Horizontal Landing
VTVL:  Vertical Takeoff Vertical Landing
WD:  White Dwarf
WFF:  Wallops Flight Facility
WFPC:  Wide Field / Planetary Camera (on HST)
WFPCII:  Replacement for WFPC
WIYN:  Wisconsin / Indiana / Yale / NOAO telescope
WR:  Western Range (was WTR)
WSF:  Wake Shield Facility
WSMR:  White Sands Missile Range
WTR:  Western Test Range
WUPPE:  Wisconsin Ultraviolet PhotoPolarimter Experiment (Astro package)
XMM:  X-ray Multi Mirror
XUV:  eXtreme UltraViolet
YSO:  Young Stellar Object
Z:  Zulu (see UT)

-- Mark Bradford ( <> To err is human, to moo bovine.
"It is good to have an open mind, but not at both ends."