Zenith (solar noon) is when the sun reaches its highest point in the sky for the day. In Islamic timing, Dhuhr becomes permissible after the sun moves past zenith — related to but not identical with zawal. Clock noon on your phone does not always match solar zenith; prayer apps calculate the solar position for your coordinates.
Zenith vs Jama'at time
The start of Dhuhr's window is a legal (fiqh) matter based on the sun. Jama'at at the masjid is when the congregation actually gathers — often 15–45 minutes after Dhuhr enters, depending on the mosque. MosqueSync shows Jama'at because that is when you need to be at the masjid.
Seasonal shifts
Zenith and Dhuhr move slightly throughout the year. Mosque editors update seasonal schedules on MosqueSync so worshippers in Kashmir and elsewhere see current times without guessing.