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Flares From the Giant ar 9433 on 24 April 2001
Uddin, Wahab; Chandra, Ramesh; Joshi, Anita
We present Hα CCD observations of three small-to-medium-size two-ribbon flares observed in the giant AR 9433 on 24 April 2001. Flare observations at other associated wavelengths (e.g., soft X-rays (SXR), hard X-rays (HXR), microwaves (MW)) obtained from archives are also presented and compared. We have tested the Neupert effect for the most energe…
Periodicities Near 160 Minutes in Flare Occurrence
Bai, Taeil
The 160.01-min periodicity was originally found from line-of-sight velocities of the photosphere, and Kotov and Tsap reported a detection of the same periodicity in flare occurrence times. Intrigued by this, I analyze occurrence times of flares of cycles 19-23 to investigate periodicities in the neighborhood of 160 min, cycle by cycle. The 160.01-…
Acceleration Effects in MDI Magnetogram Data
Norton, A.; Settele, A.
Acceleration effects are found in the Michelson Doppler Imager (MDI) magnetogram data because changes in the line profiles during the 30-s measurement are introduced by underlying p-mode velocity variations. This imparts an oscillatory component to the magnetic flux signal. Simulated profiles using Maltby M and Harvard Smithsonian Reference Atmosp…