Are halachic times for prayer, comencing Shabbos, ect. calculated according to a persons exact location or is there one "time-zone" for the entire city?

And if yes, how would this apply for large cities such as New York City or Yerushalayim (may it be rebuilt), could each neighborhood count as its own city? From where in the city is the zmanim determined; Maybe the center, or the synogogue or the earliest point? Sources and explanations apreciated.

NB: as a fun bonus question, if the time is determined by the exact location what do we do when a person is half in and half out of shabbos? (This happens very breifly twice every week.) Does it follow rosho-v'rubo? Is it chatzi shiur assur min hatorah? I know this is entirely not practical, but I take a que from the Chazon Ish in his קונטרס יח שעות on the halachic international dateline.

שעיקרי ההלכות הם עצילות, ורק אחר צמצום אחר צמצום הם משתמשים בעולם העשיה.

Related: Precise Zemanim?

  • I beleive I saw in a sefer that it follows the city, but I don't know where or why. On the other hand many luchos / zmanim services are calculated to an exact address. Commented Mar 31, 2023 at 4:17
  • Extra Extra Bonus: What is the one other place (to my knowledge) where Chazo"I uses kabbalah terminology? Commented Mar 31, 2023 at 4:18
  • 1
    Many luchos I've seen warn that the times should be treated as approximate due to city size (ie it follows the person), and there isn't much in the way of a good theoretical argument to follow the city (except maybe Kabbalas Shabbos in some cases)
    – AKA
    Commented Mar 31, 2023 at 11:52
  • @NaftaliTzvi you're going to have to be more specific than that. He writes in many many places about klipot, lights, apples, actions, lights...
    – Avraham
    Commented Apr 2, 2023 at 11:29
  • @Avraham I guess I wasn't aware. I would love to see where examples of all those are! I am reffering to a place where he writes "לית מגרמא כלום" the phrase used to describe Malchus. Maybe I should have said the two places where he refferences sefirot? Commented Apr 4, 2023 at 3:52


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