| Abbreviation | Definition |
|---|---|
| ASWG | Astronomical Science Working Group |
| ASWG | ATST (Advanced Technology Solar Telescope) Science Working Group |
| ATLAS | Advanced Technology Large-Aperture Space Telescope |
| ATM | Amateur Telescope Maker |
| ATM | Amateur Telescope Making |
| ATM | Apollo Telescope Mount |
| ATPI | Astronomy Through Practical Investigations |
| ATR | Absolute Time Reference |
| ATST | Advanced Technology Solar Telescope |
| AU | Alternate Universe |
| AU | Astronomical Unit |
| AUDS | ALFA Ultra Deep Survey |
| AVAC | Antelope Valley Astronomy Club |
| AVM | Astronomy Visualization Metadata |
| AVMS | Astronomy Visualization Metadata Standard |
| AVO | Astrophysical Virtual Observatory |
| AWG | Astronomy Working Group |
| AZA | Analiza Zanieczyszczenia Atmosfery |
| BAAS | Bulletin of the American Astronomical Society |
| BART | Big Astronomical Reflecting Telescope |