MOOL Nanakshahi Calendar (2003) was established by Sikh scholarly bodies based on astronomical research by Pal Singh Purewal. It fixes all major Sikh Gurpurbs and Sangrands to specific dates — making them perpetual (same date every year, forever).
Key principle: Purewal's calendar is a tropical solar calendar. 1 ਚੇਤ always falls on 14 March. Sangrands always fall on fixed dates. All Guru Gurpurbs have fixed dates that never drift.
⚠️ Non-MOOL events (shown in orange) follow the older Bikrami (Hindu lunar) calendar. Because the lunar year is ~11 days shorter, these dates shift each year.
🔴 Red events were in Purewal's primary sources but missing from the NNS Khalsa Jantri — they have been added here for completeness.
Sources: NNS Khalsa Jantri (Singh Brothers, Amritsar) · Pal Singh Purewal primary sources · nanakshahicalendar.org