It is Nammalvar Jayanti, but abhishekam only to mark it since it comes in the middle of the Brahmotsavam.
Brahmotsavam Day 8 Schedule:
Vennai Thazhi and Horse Vahana in the evening; Nammalvar Jayanti Abhishekam.
07:00 AM: Vennai Thazhi (Butter Pot) Appearance Procession – with the cutest chaatrified baby backside – Munnilum Pinnazhagiya Perumal (முன்னிலும் பின்னழகிய பெருமாள்), as they say of Namperumal, the processional deity of the Sri Ranganathaswamy Temple in Srirangam.
10:30 AM: Thirumanjanam
08:00 PM: Procession on Horse Vahanam–Thirumangai Alvar sits on the horse named Adalma who carried him across various regions as he travelled to visit and sing praises of the 108 Divya Desams.