All these pictures were taken at the Etnographic Museum near the Blue Mosque and Blue Türbe.
Hat (called ‘taç’ = crown) of a Sheikh (turkish: Şeyh) of the Mısri Tarikatı, a Sufi Order founded in the 17th century.
From Wikipedia: Sufism is defined by some adherents as the inner, mystical dimension of Islam, others contend that it is a perennial philosophy of existence that pre-dates religion, the expression of which flowered within Islam. A practitioner of this tradition is generally known as a sufi. They belong to different "orders" - congregations formed around a master - which meet for spiritual sessions, in meeting places known as zawiyahs, khanqahs, or tekke.
Correspondent: J.M.Criel, Antwerpen.