Wikipedia
Haridatta (ca. 683 CE) was an astronomer- mathematician of Kerala, India, who is believed to be the promulgator of the Parahita system of astronomical computations. This system of computations is widely popular in Kerala and Tamil Nadu. According to legends, Haridatta promulgated the Parahita system on the occasion of the Mamankam held in the year 683 CE. Mamankam was a 12-yearly festival held in Thirunnavaya on the banks of the Bharathapuzha river.
The distinctive contribution of Harfidatta, apart from his resolving the Aryabhatiya calculations and using the Katapayadi system of numerals is the corrections he introduced to the values of the mean and true positions, the velocity, etc., of the moon and other planets as obtained from Aryabhata's constants. This correction is called the Sakabda-samskara since it applied from the date of Aryabhata in the Saka era 444, at which date his constants gave accurate results.