Hindu calendar (lunar) to Gregorian calendar 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)

I don't have the entire answer but I hope this will at least help a bit you if not more.
Have you looked at http://www.webexhibits.org/calendars/calendar-indian.html
Quoting:
"All astronomical calculations are performed with respect to a Central Station at longitude 82°30’ East, latitude 23°11’ North."
Why do you wish to convert these dates?
If this is a one-time thing, you might be able to find something that does it for you.
I found http://www.rajan.com/calendar/ but this is Gregorian <> Nepali (I was under the assumption that it is the same, maybe it isn't)
