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Teams
STEM October Astronomy Club presents
Global Astronomy
& Astrophysics Challenge
GAAC is an international team competition for students who can connect astronomy, astrophysics, and observation into precise scientific reasoning.
Registration opens on 12 July 2026.
GAAC 2026
2026 Stats.
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Participants
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Countries represented
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Teams reach knockouts
Competition Format
Individual qualification, then collaborative knockouts.
Individual Qualification
Each participant competes individually for 1 hour across 40 multiple-choice questions. The three scores are combined, and the top 16 teams advance to the Round of 16.
Round-of-16 Qualifier
The top 16 teams compete individually in 20 more-challenging multiple-choice questions within a 30-minute limit.
Round 2 - Knockout
The 8 strongest teams meet in supervised Zoom matches, solving 10 problem-solving questions together as a team.
Final Results & Certificates
Winners are announced on 16-17 September and all participants and ambassadors receive their certificates.
Official Rules
The rulebook behind every round.
Official Document
Competition Structure & Scoring System
The complete GAAC rulebook: the full round system, the unified scoring model, proctoring conduct for every supervised session, the knockout ladder, and the official rules at a glance.
Download Rules PDFGAAC Pages
Explore the challenge.
01
Syllabus
The six domains tested across both rounds of GAAC.
02Timeline
Registration dates, competition window, and stage progression.
03Prizes
Trophies, medals, and awards for the top-scoring teams and ambassadors.
04Partners
STEM October Astronomy Club and the organizations supporting the season.
05Ambassador
Represent your school or region, help grow the community, and earn recognition.
06Team Dashboard
View your team and let the leader manage the roster during registration.
Ambassador Program
Become a GAAC Ambassador.
Represent your school or region, help grow the community, and earn recognition for spreading the word. Ambassadors who drive successful registrations climb the leaderboard and gain exclusive access.
Apply Now
Organized By
STEM Astronomy Club
GAAC continues the club mission of making astronomy and astrophysics more accessible, rigorous, and international for ambitious students.
Visit the main club website →