Prayer: Time for Performing Salat al-Ayat for a Solar or Lunar Eclipse
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 1474
The time for performing ṣalāt al‑āyāt for a solar or lunar eclipse commences from the moment the eclipse begins, and it continues until the sun or the moon goes back to its normal state (although it is better not to delay the prayer until the eclipse starts to reverse). However, completing ṣalāt al‑āyāt can be delayed until after the eclipse is over.[1]
-Ayatullah Sistani, Practical Laws of Islam, Prayer (Salah)
1
This means that although a person must start performing ṣalāt al‑āyāt during the eclipse, he can continue performing it while the eclipse continues and does not need to finish it before the eclipse is over.