Official Indian National Calendar proposed by a team led bySenior Indian Astrophysicist Meghnad Saha [1]. Borrows from Indian and western calendars.

It also fixes issues with traditional Indian calendar of makara sankranthi[2]

en.m.wikipedia.org/wiki/Indian

1. Report by Saha and team (PDF).
dspace.gipe.ac.in/xmlui/bitstr

2. Medieval mistake
frontline.thehindu.com/other/a