Montana State University Solar REU Program 2011
~Casey Donoven~


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    Week 10-

    Week 9-

    Week 7 and 8-



I noticed that my velocities seemed unreasonably high after some simple calculations so Angela suggested that I smooth the data for more accuracy. This would reduce noise due to resolution problems with Rhessi and changing footpoint shape. I wrote a program that allowed me to average over several positions and times so I could use these averages to do my calculations. These are graphs of the average speed vs number of positions/times averaged in my program. Clearly, the more I average, the more the speed is reduced, but there is a point where the speed decreases less. I am now trying to determine the point at which the speed is most accurate.



































This is a quick plot of the footpoints from the below movie. The colorbar didn't want to cooperate so I left it off.

January 19, 2005 Rhessi Images
This is a movie of the first truly successful images I've made of a SHS flare. Typically, SHSs flare are smaller than SHH flares making it more difficult to get enough counts for images.

    Week 6-

November 2, 2003 Rhessi Images
I apologize for the quality of the movie. I'm seeing if I can fix it. For now, I suggest stepping through it slowly to see the individual frames.

StatisticBottom Left Footpoint
x coord avg485.506
x coord stddev2.10160
y coord avg-111.316
y coord stddev3.74826
x velocity avg-2.89582
x velocity stddev51.8108
x speed avg35.9432
x speed stddev36.5604
y velocity avg13.4130
y velocity stddev74.0920
y speed avg49.6211
y speed stddev55.6162
speed avg70.3597
speed stddev56.3355

This is data from the May 29, 2003 flare at 01:05. The upper right footpoint was so dim that it was barely, if at all, visible for most of the flare.
Also, the looptop source was bright, so I had to use a higher flux percentage, .97, to identify the bottom footpoint.

I managed to download Rhessi data for all of the x-class flares on my list. All of the x-class flares, save one, show SHH behavior.



























This is the corrected data with the correct magnetogram.

StatisticRight Footpoint- oldRight Footpoint- new
x coord avg694.499694.697
x coord stddev5.145655.13136
y coord avg-159.733-159.690
y coord stddev3.911363.97782
x velocity avg16.1563-17.5636
x velocity stddev163.257125.442
x speed avg115.86293.2275
x speed stddev115.09384.8038
y velocity avg2.541454.62923
y velocity stddev114.052114.594
y speed avg82.219582.4741
y speed stddev78.288678.8721
speed avg154.945134.349
speed stddev124.422103.957

After noting the two times in which the right footpoint jumps back to the left, I examined the original images to find that the footpoints were ill defined in those times.
The centroids calculated during those times encompassed both footpoints and the looptop source giving erroneous data. I reran the calculations excluding those points.



























This is a magnetogram overlayed with the positions the of the centroids of the footpoint colored according to the time.
Please note, this is the wrong month and year for the magnetogram. My apologies.

StatisticRight FootpointLeft Footpoint
x coord avg694.499670.277
x coord stddev5.145651.55149
y coord avg-159.733-160.102
y coord stddev3.911361.80427
x velocity avg16.1563-3.43896
x velocity stddev163.25739.0756
x speed avg115.86231.4448
x speed stddev115.09322.0187
y velocity avg2.541458.68796
y velocity stddev114.05260.8459
y speed avg82.219542.5619
y speed stddev78.288643.0169
speed avg154.94557.5358
speed stddev124.42242.3225

I have revamped my program to calculate speed more accurately, using x and y speeds rather than x and y velocities.
Here is the new output from my program.

    Week 5-

StatisticRight FootpointLeft Footpoint
x coord avg694.499670.277
x coord stddev5.145651.55149
y coord avg-159.733-160.102
y coord stddev3.911361.80427
x velocity avg16.1563-3.43896
x velocity stddev163.25739.0756
y velocity avg2.541458.68796
y velocity stddev114.05260.8459
speed avg16.35509.34382
speed stddev199.15072.3127

I wrote a program that extracts data from flux output files, calculates velocities of the centroids of the footpoints, and makes a structure containing all of the data including statistics.
This is a table of the data from the March 18, 2002 flare. The large standard deviations makes me worry about the accuracy of my method.

    Week 4-






















                          The left footpoint's coordinates                                                                                                      The right footpoint's coordinates.






















                          The left x coordinate v time                                                                                                              The right x coordinate v time






















                          The left y coordinate v time                                                                                                              The right y coordinate v time






















                          A typical image of both footpoints

Using the Rhessi GUI, I calculated the centroids of the footpoints during the April 18, 2003 flare. Here are plots of the data.
(Note: the time scales are completely off and are in unix time, while the position is in arcsecs.)

    Week 3-
































This is a magnetogram overlayed with contours of the footpoints (blue, green, and then yellow) and the looptop (red).
The flare moves upward during this time frame and the looptop shows what direction the flare is pointing.

I also looked into the "hump" after the flare but the data seemed to be just noise and many images couldn't even be made.

I explored different energy ranges to separate the footpoints and the top of the flare, but to no avail.
The top can easily identified using the 20 to 40 keV range but using higher energies resulted in fairly messy images without clear footpoints.






















I made a higher resolution image using all nine detector on Rhessi, which made the image much, much cleaner.
The bottom footpoint is dim though and making contour plots didn't seem to help identify it very well.






















During the flare, what I believe to be the top of the flare shows up in the data and makes the footpoints harder to see.
Even making contour plots of the image doesn't help as the top is so bright it hides the footpoints.






















The bright spots are the footpoints of the flare. I will use a magnetogram to determine which footpoint is positive and negative or if one is actually the top of the flare.

I spent a bit of time examining the August 3, 2002 flare that occured at 19:07.
This flare had some well defined footpoints as well as a slight 'hump' in xray emissions after the majority of the flare was over.

    Week 2-

Angela and I were able to find data on when the attenuators change during a flare, which I will use to make sure future plots are less messy.






















Here is a lightcurve that shows how many photons are detected by the colliminators on the rhessi satelite on July 3, 2002 from 02:09 to 02:16
The attenuators switched on and off during the time interval making my first attempts at making images go haywire.

I was able to make images (to be made into contours) of the April 17, 2002 flare in 20 second intervals but 4 of the 131 images were blank due to a lack of data.
The July 3, 2002 gave me more trouble as roughly a third of the images were blank because the attenuators kept changing to eliminate excess soft xray data.

From the contours of the fotpoints, I can calculate the centroid of each consecutive footpoint.
With this data, coupled with their positions on the sun, I will eventually be able to calculate velocities.






















This is a magnetogrma with the footpoint of a flare overlayed. You can see the footpoint of the flare move, from blue to purple, over 6 different 12 second intervals.
The footpoints come from hard xray data collected by the Rhessi satelite.

    Week 1-






















This is a magnetogram of the sun with an overlayed contour plot of xray data from the Rhessi satelite. These xrays are mostly soft xrays, highlighting the top of the flare.
I used my journal entries from IDL to help make a script that will replicate this image for my project.

I started some of Angela's tutorials this week.