Rewrite each original sentence in order to make it easier to understand by non-native speakers of English. You can do so by replacing complex words with simpler synonyms (i.e. paraphrasing), deleting unimportant information (i.e. compression), and/or splitting a long complex sentence into several simpler ones. The final simplified sentences need to be grammatical, fluent, and retain the main ideas of their original counterparts without altering their meanings.

Romulus, the first moon, was discovered on February 18, 2001 from the Keck II telescope by Michael E. Brown and Jean-Luc Margot.
Romulus is the first moon. It was discovered on February 18, 2001 from the Keck II telescope.

It was not detected again until the Hubble Space Telescope observed it in 1997.
The Hubble Space Telescope observed it again in 1997.

With exceptions, the Fatimids were reputed to exercise a degree of religious tolerance towards non-Ismaili sects of Islam as well as towards Jews, Maltese Christians and Coptic Christians.

The Fatimids used religious tolerance towards non-Ismaili sects of Islam and towards Jews, Maltese Christians and Coptic Christians.

