There is a popular belief that Rajendra was born on Margazhi Thiruvadhirai.. Though Rajendra's birth star is Thiruvadhirai - it appears he was not born in Margazhi..
will mail relevant details within a week or so.
However it is worth remembering Rajendra I on this auspicious occasion,
Likewise there is another popular beliefs that ::
1. there were 9 Sadai's (hair-do in lot (?) in Nataraja prior to Rajendra and 2. There was not Ganges in the Sadai of Nataraja..
AND the 9 Sadai became 10 & Ganges added ONLY AFTER RAJENDRA's Northern Expedition and bringing Ganges.
this also appears to be a theory without support.
Anyhow study of Nataraja is interesting - as always !!
Seeyamangalam Stone Nataraja is the first one to have AGNI in hand !!