A&A: Astronomy & Astrophysics
AAO: Anglo-Australian Observatory
AAS: American Astronomical Society
AAT: Anglo-Australian Telescope
AAVSO: American Association of Variable Star Observers
ABRIXAS: A Broadband Imaging X-ray All-sky Survey
AC: Astrographic Catalogue
ACE: Advanced Composition Explorer
ACIS: Advanced CCD Imaging Spectrometer
ACM: Asteroids, Comets, Meteors
ACP: Aerosol Collector and Pyrolyser
ACS: Advanced Camera for Surveys
ACV: Alpha Canes Venatici
ACYG: Alpha CYGni
ADAF: advection-dominated accretion flow
ADC: Astronomical Data Center
ADEC: Astrophysics Data Centers Executive Council
ADF: Astrophysics Data Facility
ADIS: Astrophysics Data and Information Services
ADS: Aitken Double Stars
ADS: Astrophysics Data Service
AFGL: Air Force Geophysics Laboratory
AG: Astronomische Gesellschaft
AGAPE: Andromeda Galaxy and Amplified Pixels Experiment
AGB: asymptotic giant branch
AGK: Astronomische Gesellschaft Katalog
AGN: active galactic nucleus
AGU: American Geophysical Union
AIM: Aeronomy of Ice in the Mesosphere
AIPS: Astronomical Image Processing System
AJ: Astronomical Journal
ALaMO: Automated Lunar and Meteor Observatory
ALEXIS: Array of Low Energy X-ray Imaging Sensors
ALMA: Atacama Large Millimeter/Sub-millimeter Array
ALPO: Association of Lunar and Planetary Observers
AMANDA: Antarctic Muon and Neutrino Detector Array
AMASE: Astrophysics Multi-spectral Archive Search Engine
AMS: American Meteor Society
AN: Astronomische Nachrichten
ANS: Astro News Service