<Tr> <Td> 16 . DEC 26 - JAN 14 </Td> <Td> 16 . NOV 29 - DEC 18 </Td> <Td> Atemoztli </Td> <Td> </Td> <Td> Descent of the Water </Td> </Tr> <Tr> <Td> 17 . JAN 15 - FEB 03 </Td> <Td> 17 . DEC 19 - JAN 07 </Td> <Td> Tititl </Td> <Td> </Td> <Td> Stretching for Growth </Td> </Tr> <Tr> <Td> 18 . FEB 04 - FEB 23 </Td> <Td> 18 . JAN 08 - JAN 27 </Td> <Td> Izcalli </Td> <Td> </Td> <Td> Encouragement for the Land & People </Td> </Tr> <Tr> <Td> 18u . FEB 24 - FEB 28 </Td> <Td> 18u. JAN 28 - FEB 01 </Td> <Td> nemontemi (5 day period) </Td> <Td> </Td> <Td> Empty days (no specific activities or holidays) </Td> </Tr>

What was the aztec lunar calendar based on