The AGB population of NGC 6822: distribution and the C/M ratio from JHK photometry L. F. Sibbons, S. G. Ryan, M.-R. L. Cioni, M. Irwin and R. Napiwotzki A&A, 540 (2012) A135 Published online: 12 April 2012 DOI: 10.1051/0004-6361/201118365