We have to convert the Hindu calendar (the lunar one) to the Gregorian calendar. According to the (Dutch) Wikipedia (sorry for that, but it has more information than other websites), it is based on he angle between the sun and moon. Now I have many questions about that, such as what angle do they mean? If I draw a line between the sun and moon, I am missing a line to calculate the angle. But the more concrete question is: how can we convert from the Hindu calendar to the Gregorian calendar? Also, we have noticed that the conversion is not injective; it can happen that one Hindu date relates to two Gregorian dates. We decide in that case to pick the first Gregorian date, but we are still not able to convert dates.
One of the days we know the conversion of is:
Basant Pachami (d-m-Y) : 5-11-2068 (Hindu) : 1-28-2012 (Gregorian)