Sage Lagadh is the author of Vedang Jyotish, which dates back to atleast 1400 BCE.
I wanted to know where all, has he been mentioned in other scriptures of Sanatan Dharm and oral history.
Sage Lagadha in Vedanga Jyotisha says Uttarayan was situated in in Sravistaa Nakshatra (293.20deg to 306.40deg) during his time. Currently Uttarayan is taking place in Moola Nakshatra beginning i.e 210deg. Uttarayana will stay in a nakshatra for approx 1000 years. The time of Sage Lagadha was actually 4000 to 5000 year back from now.