topas_nmon was officially supported by IBM. By Default installed on AIX (Since AIX 5.3 TL9 AIX 6.1 TL2).
crontab -e and put the below entry
00 12 * * * /usr/bin/nmon -s 60 -c 1440 -f -d -t -P -r <server name> -o <full path of directory where file to be written>