%0 Journal Article
%@ 978-979-16353-1-8
%A Bachtiar, Anwar
%A Bambang, Setiahadi
%D 2008
%F UNY:6876
%I Jurusan Pendidikan Matematika Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Negeri Yogyakarta
%J PROSIDING SEMINAR NASIONAL MATEMATIKA DAN PENDIDIKAN MATEMATIKA
%T Activities in Sunspot Group NOAA 9393
%U http://eprints.uny.ac.id/6876/
%X Watukosek Aeronautics and Space Observing Site (WKSO, LAPAN), observed sunspot in daily basis since 1987 using a sketch method. Sunspot group NOAA 9393 (or WKSO 0123) have been observed in March to early of April 2001. The region showed a rapid development during its appearance on the solar disk. The magnetic field of this active region evolved from a simple to a complex configuration (sunspot group type F) within a short period (days). WKSO recognized the sunspot group remains as type F (very active) as long as 8 days. Based on GOES data the active region released as much as 56 flares of type C (small), M (moderate) and X (large) to amount of 28, 24 and 3, respectively, during its appearance from 24 March to 4 April 2001. It is found that prior to X-class flare, there was an increase of activity in C and M-class flare. A rapid emergence of the active region may cause instability in magnetic configuration, and therefore released the magnetic energy in the form of solar flares.    Keywords: Sunspot group, active region, solar flares, solar activity