My suggestion would be to look at some of the Tamil Śaivasiddhānta Daśakārya texts, or paddhatis related to them - some of them are available in that fabulous resource the Tamil Digital Library - which might have a section on navagraha worship. Further, there
is a collection of stotras to the Navagrahas and Caṉipakavāṉ which is also available in the Tamil Digital Library under the following title:
நவக்கிரகத் தோத்திரம் சனிபகவான் தோத்திரம்
Associate Professor of Hinduism,
University of Toronto.
From: INDOLOGY <email@example.com> on behalf of Ofer Peres via INDOLOGY <firstname.lastname@example.org>
Sent: July 23, 2020 11:21 AM
To: Indology <email@example.com>
Subject: [INDOLOGY] Navagraha worship in Tamil literature
Dear list members,
I would be grateful for any reference to pre-modern Tamil literary texts (or Sanskrit texts that originated from the Tamil-akam) that mention Navagraha-worship and the worship of Saturn in particular.
The Hebrew University of Jerusalem.