Sekaten is an acculturation of local tradition ceremony with Islamic tradition. At that time, the king of Demak named Raden Patah with The Wali utilizing gamelan (traditional music instrument) to attract people who like gamelan by providing requirement to say two sentences creed (Syahadatain) as a sign of their conversion to Islam. Until now, the Yogyakarta palace continues the tradition of gamelan sekaten for seven days, from May 5 to 11 Maulud according to the Javanese calendar.
In Yogyakarta Palace, the gamelan sekaten consists of two rancak (sets), named Kyai Kanjeng Nogowilogo and Kanjeng Kyai Guntur Madu. The Sekaten ceremony in Yogyakarta began on 5 Maulud in the afternoon by releasing two sets of gamelan sekaten from the place named Bangsal Ponconiti in Yogyakarta Palace. Both of gamelan carried through Siti Hinggil, Pagelaran, and North Square and to the courtyard of Masjid Gedhe (the Great Mosque). This procession named Miyos Gongso.
In the mosque complex, both of gamelan will be placed separately. The gamelan named Kanjeng Kyai Nogowilogo is placed on the north side of the Masjid Gedhe or called Pagongan Lor, while Kyai Gunturmadu is placed in the Pagongan Kidul or in the south of the mosque. Both of gamelan will be played alternately for seven consecutive days. Then, in the evening of 11 Maulud, the two gamelan will be brought home to the Sultan Palace with the ceremony named Kondur Gongso. The Gamelan sekaten was then issued again in the next year.
*Also posted in Bahasa Indonesia here.