IAUC meaning in International ?

Answer: What is International Astronomical Union Circulars mean?

The International Astronomical Union Circulars (IAUCs) are notices that give information about astronomical phenomena. IAUCs are issued by the International Astronomical Union's Central Bureau for Astronomical Telegrams (CBAT) at irregular intervals for the discovery and follow-up information regarding such objects as planetary satellites, novae, supernovae, and comets.

reference

Full Form	Category
International Advanced University Credit	Academic & Science
International Association of Urban Climate	Academic & Science
Irish American Unity Conference	Community
Incremental Area Under the Curve	General
Initial Area Under Curve	General
International Association for Urban Climate	International
International Advance University Credit	International
International Astronomical Union Circulars	International