NAV of Pension Fund - Scheme G

Dear All,

Can someone please help me How the NAV of G Scheme Pension funds work. Most of these Pension Funds are invested in long term Government Bonds then how come we see sudden drop in the NAV?

For example - ICICI Prudential Pension Fund - Scheme G - TIER II
Check NAV on 20 and 26 Aug or 29 Jan to 5th Feb.

How to decide best time to decide when to invest? Any observations?

Regards
@rupeshmandal, @Bhanu

Start here and read all the 3 chapters on debt funds