Use any method from this StackOverflow answer to get and store a timezone id for each masjid on masjid creation (and migrate existing data on deploying this)
Use suncalc to calculate sunset times, then use moment timezone to convert to the timezone of the masjid
This improves on the current approach of just doing a rest call to geonames.org.
This improves on the current approach of just doing a rest call to geonames.org.