Question: What do Al-Nayrizi and Avicenna have in common?

Context paragraphs:
Cerastes vipera: Cerastes vipera, common names Sahara sand viper and Avicenna viper, is a venomous viper species endemic to the deserts of North Africa and the Sinai Peninsula.  No subspecies are currently recognized.

Avicenna: Avicenna or Ibn Sīnā (Persian: ‎ ‎ ;  – June 1037) was a Persian polymath who is regarded as one of the most significant physicians, astronomers, thinkers and writers of the Islamic Golden Age.

Al-Nayrizi: Abū’l-‘Abbās al-Faḍl ibn Ḥātim al-Nairīzī (Arabic: أبو العباس الفضل بن حاتم النيريزي‎ ‎ , Latin: "Anaritius, Nazirius" , 865–922) was a Persian mathematician and astronomer from Nayriz, Fars Province, Iran.

Supporting paragraphs: Al-Nayrizi Avicenna
Answer: astronomers