Panchangam means five attributes of Hindu calendar day that is Tithi, Vaar, Nakshatra, Yoga and Karana. It is the official astrological calendar of practicing Hindus. Most of panchanga`s attributes depend on sunrise time. That`s why it is so important to use internet-panchanga calendar, which takes into account yours position exactly.
Maha Shiva Ratri date could be different in different places of the World. For example:
10 march 2013 in Delhi 9 march 2013 in New York
Panchangam is both Solar and Luni-Solar. Most holydays depend on Tithi (angular relationship between Sun and Moon) and Moon month. Maha Shiva Ratri day changes from year to year by western calendar. For example: