Everyone in India has their favorite panchangam and the family priest they use to perform puja and muhurtha. The problem comes here. Whenever you approach him he'll give you muhurtha as per indian time and then will say subtract the time difference from india to your country. This is the wrong thing. If you are living abroad then you should use panchangam for that location because you cannot use muhurtham you have got from one city in india in another city. For example: if you got muhurtham for chennai or hyderabad you cannot use it in New Delhi or Kolkata because their sunrise, sunset, longitude, latitude will be different.
At times people also refer to the readymade muhurtha available in calendars like kaalnirnay or similar panchangas. The readymade muhurtha available in most online panchang or print panchang are based in India (Printing cost is very expensive hence they don't make for other countries), and they are very general purpose for use within india or city they are targeted for. Even if you are living in India, it may not be applicable to you. Those ready made muhurthas are certainly not applicable outside of india. Most people living abroad think that they can safely subtract their time difference from india time and get muhurtha. This is completely wrong assumption. One cannot substract the timezone from muhurtha given in indian panchangam or by an astrologer in india by just subtracting the timezone. If the astrologer has taken longitude, latitude and local sunrise of the place into calculation then its okay. Otherwise it's not. Please remember that panchangam available in india are designed and prepared only for india and they cannot be applicable outside of india. It is sad that most well educated indians who live abroad still think muhurtha abroad = indian muhurtha time - time difference.
Please remember one needs to calculate muhurtha for your city. Please note that that muhurtha calculated for Chennai or Hyderabad will not be applicable to New delhi (And they are in the same time zone. Using those indian muhurtha abroad is different thing altogether).
Following important points for calculating muhurtha:
- Muhurtha is heavily dependent on local events like local sunrise, sunset. Most coutries in northern latitudes beyond 35 degrees north will have sunrise in summer around 4:00 am. The sun will set in winter around 9:30 pm or even beyond. During winter sun will rise after 8:00 AM and will set around 3:30 PM. This isn't case with india.
- One will note that on Mondays rahukalam starts at 7:30 am. Now during winter if sun rises at 8:15 AM how can rahukalam start at 7:30 AM? before the sunrise? This is another wrong assumption using fix rahukalam timings. The standard time and clocks were introduced by britishers in india, before that we used ghati--gadiyalu etc... Hence this means one can't even use fixed rahukalam even in india using abroad is wrong thing. Rahukalam etc are dependent on local events like the sunrise, sunset etc....
- Another important factor in calculating muhurtha is the lagna shuddhi. Lagnashuddhi is the boss of muhurtha. Lagna shuddhi means removing afflication by planets at the time of muhurtha. Now to do that we prepare jatakam / kundali at the time of muhurtha which is heavily dependent on local longitude, latitude. This means you cannot convert time to indian time and prepare kundli / jatakam.
- Among many other factors, one has to check rasi bala,tara bala, surya bala, guru bala, agnivasa, udayastha, chandara mukham (for graha pravesha etc...) and other details.
