The Grand Ayatollah Sistani answered questions about sighting the new moon.
Question: Considering big differences in sighting the new moon:
- What is the criterion for sighting?
- Is it enough to use the existing calendars or it must be announced on behalf of Maraje’a (grand scholars)?
- Isn’t sighting the moon in one country the criterion for other countries? How far is the horizon (skyline) of a country?
- Must other towns in a country follow a town where the moon is sighted?
The Grand Ayatollah Sistani:
- Seeing the moon with normal eyes without any equipment.
- Calendar on its own is not credible.
3 & 4. Yes, like Karbala and Najaf if according to width of horizon are near each other.
Source: PERSIAN SHAFAQNA