On average (defined by the median of the distributions), the duration, rise and decay times of the flares were estimated to be 20.8 minutes, 5.6 minutes, and 14.2 minutes, respectively. Based on the obtained flare list, statistics on the temporal behavior such as the duration, rise, and decay times, and the event asymmetries of Ly α flares is presented. This algorithm is designed to search events at various scales and find their real start and end times. In the present work, we produce a Ly α flare catalog from the GOES-15/EUVS-E data between 2010 April June 6 with an automatic flare detection algorithm. The Geostationary Operational Environmental Satellite (GOES) series, starting with GOES-13, began to carry a multichannel Extreme UltraViolet Sensor (EUVS) with one channel (E-channel) targeting the Ly α line. The emission at this line could be a major energy input to the upper layers of the Earth’s atmosphere, strongly impacting the geospace environment. The Lyman-alpha (Ly α ) line of neutral hydrogen at 121.6 nm is by far the brightest emission line in the vacuum ultraviolet spectral range of the Sun. The stray-light measurement results for SCI in the laboratory show that the stray-light level can be suppressed to the order of 10−8 B⊙ at 2.5 R⊙ (B⊙ is the mean brightness of the solar disk) in the white-light (WL) band, which is consistent with the stray-light level obtained by simulation and verifies the modeling and simulation. The scattered stray-light from the primary mirror, including the surface errors, cosmetic defects, and particulate contamination, is analyzed and suppressed, and the corresponding scattering models are established for simulation based on the laboratory testing. In this study, a stray-light suppression method is adopted for Solar Corona Imager (SCI) which is a dual-waveband internally occulted reflecting coronagraph simultaneously and independently observing the inner corona in the HI Lyman-alpha (121.6 ± 10 nm) line and white-light (700.0 ± 40 nm) wavebands with a field-of-view (FOV) from 1.1 to 2.5 R⊙ (R⊙ stands for the mean solar radius). In order to achieve a clear observation of the ultra-low brightness solar corona and provide a physical basis for forecasting space weather that seriously affects the human living environment, the stray-light suppression level becomes the key factor affecting the development of the coronagraph.
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