Most panchang apps and printed calendars are built for India and default to IST. Reading them correctly from a US time zone takes one extra step most people skip.
The mistake: converting the clock time instead of recomputing
Simply subtracting 9.5 to 13.5 hours (depending on the US time zone) from an IST muhurat window does not give you your local muhurat. Tithi, nakshatra, sunrise and sunset are all tied to your actual location, they need to be computed for your city, not translated from India’s numbers.
What changes for a US city
Sunrise and sunset times, which anchor Rahu Kaal, Abhijit Muhurat and several other windows, depend on your city’s own latitude and longitude. A city like Seattle has very different day-length swings across the year compared to Chennai, which changes when these windows fall.
Getting it right
Use the panchang page or muhurat page and select your actual US city (or the nearest listed one in your time zone), rather than reading an India-based panchang and doing mental time-zone math.
For more on using these tools correctly from abroad, see the guide for Indians abroad.
This information is descriptive.