NAO — National Astronomy Olympiad (generic national program)
A template for the national astronomy olympiads that most countries run to select their IOAA or IAO teams — such as the OBA in Brazil or national rounds in India and Japan. Structures differ, but most combine written rounds with a final selection camp.
- Host rotation
- National, within each participating country
- Level
- National (varies by country)
- Format
- Multi-stage national selection feeding the IOAA or IAO
- Rounds
- School/local round, regional round, national final, team selection camp
- Eligibility
- Secondary-school students of the organizing country, subject to each program's age rules
- Website
- ioaastrophysics.org
Notable facts
Brazil's OBA is among the largest science olympiads in the world, reaching millions of students. National programs are the main gateway to international astronomy competitions.
Recent editions
Hosted nationally, at multiple sites each year.
Typical topics
Past problems
2024
Limiting magnitude of a small telescope
An observer under dark skies sees stars down to magnitude 6 through a 7 mm pupil. Estimate the faintest magnitude reachable with a 150 mm telescope under the same conditions, ignoring instrumental losses.
Show solution
Light grasp scales with aperture area, so the limiting-magnitude gain is Δm = 5 log(D2/D1) = 5 log(150/7) ≈ 5 × 1.33 ≈ 6.7 mag. The telescope therefore reaches m_lim ≈ 6 + 6.7 ≈ 12.7, roughly magnitude 13. In practice obstruction and transmission losses shave off a few tenths of a magnitude.