Nicholas Shields SESI Presentation CUA Student Brian Dennis Mentor OVERVIEW Background on GOES satellites GOES Event list Size Distribution Fit powerlaw to the size distribution What is GOES ID: 1047907
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1. Frequency Distribution of GOES Solar Flare Peak Fluxes from 1994 to 2005Nicholas ShieldsSESI Presentation – CUA StudentBrian Dennis (Mentor)
2. OVERVIEWBackground on GOES satellitesGOES Event listSize DistributionFit power-law to the size distribution
3. What is GOES?Geostationary Operational Environmental SatellitesX-ray Spectrometer3 second data in two wavelengths1-8 Angstrom0.5-4 Angstrom
4. GOES Spectra Data:
5. Event DetectionFirst we take the raw data and smooth it using either a boxcar smoothing or an average smoothingThe derivative of the data is takenWhere the derivative crosses zero we find either a peak or a valley
6. Example of Event Detection:
7. Data-drop/spike Filter:The SDAC data often has drops or spikes that we do not want to declare peaks and valleys.
8. Time FilterThe time intervals between a valley the next peak and the following valley are examined:
9. Quantization FilterQuantization level = flux value where the step size changesMatches peak flux to quantization levelDifference between peak and valley flux values must be greater than quantization step * 3
10. Effects of the Time & Quantization Filter:
11. Background Subtraction: MethodGOES satellite records even non-flaring plasmaDifficult to distinguish the flux levels of the smaller solar flaresLinear background subtractionRuns from one valley to the nextIt takes the flux level at the first valley and subtracts it from every point in the data array until reaching the next valley
12. Example of Background Subtraction:
13. Size DistributionA size distribution was performed onun-subtracted databackground subtracted data.Binned the data by the flare sizeShows the frequency of solar flares over time based on their size
14. Example of Size Distribution:
15. Power-Law FitsUsed OSPEX (object spectral executive)Automatic fit using the closest parameter settings Single power law fitdN(p)/dp = A p−α dN(p) is the number of events with a “size” between p and p + dp A is a normalization parameterand α is the power-law index
16. Power-Law Fits Example
17. Past Results
18. 1994 to 2005 Results
19. Work Still to be Done:Change to creating a size distribution for a set number of flares rather than a set time intervalUse c-statistic to find the fit parameters rather than chi-squared
20. AcknowledgementsBrian DennisAndy GopieRichard SchwartzKim TolbertFred Bruhweiler