There are five parts of Panchanga: Tithi, Var, Nakshatra, Yoga & Karan produce Panchanga together.
There are 27 types of Nakshatra. But a Jataka suffere by Dosha , If Jataka was born in following Nakshatras.
Ashwini
Bharani
Pushya(2nd , 3rd Charan)
Aashlesha
Magha(1st Charan)
Uttara
Chitra
Vishakha
Jeshtha
Mul
Purvashadha
Shatataraka
In this situation it is necessary to perform Shanti Puja Vidhi.