5 th SECCHI Consortium Meeting, May 5 2007 Tomographic Reconstruction of CMEs from White Light...
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5th SECCHI Consortium Meeting, May 5 2007Tomographic Reconstruction of CMEs from White Light Coronagraph Data
Tomographic Reconstruction of CMEs from White Light
Coronograph Data
FITS ingest, Visualization, and PIXON Current State
Alex Antunes, J.W. Cook, J. Newmark (NRL)
A. Yahil (Stony Brook University)
5th SECCHI Consortium Meeting, May 5 2007Tomographic Reconstruction of CMEs from White Light Coronagraph Data
Abstract
We discuss our 3D tomographic reconstruction approach with PIXON for SECCHI and LASCO data: setting up the geometry using datafile FITS headers, calculation of statistical noise, and input/output for the PIXON tool. In previous meetings we have discussed our PIXON 3D reconstruction tool and shown early results from synthetic modeled coronal structures. 3D tomographic reconstruction works best with multiple overlapping yet distinct viewpoints, while early in the STEREO mission, we are still at small angles of separation. We illustrate reconstruction geometry and set-up for SECCHI Cor2 data. We also discuss issues in incorporating HI data in reconstructions.
5th SECCHI Consortium Meeting, May 5 2007Tomographic Reconstruction of CMEs from White Light Coronagraph Data
Intent: Determine underlying ne density
of a CME
Means:
● FITS ingest
● Solver (Pixon or conjugate gradient or FM)
● Visualizing Datacubes
Sample: Chen flux rope with noise
Discussion and 'To Do'.
3D Reconstruction Update
5th SECCHI Consortium Meeting, May 5 2007Tomographic Reconstruction of CMEs from White Light Coronagraph Data
FITS Ingest
5th SECCHI Consortium Meeting, May 5 2007Tomographic Reconstruction of CMEs from White Light Coronagraph Data
Fit to the noise, then stopDN to Photons:
dataphotons = dn2photons * (dataDN – biasmean)sigmaphotons= √dataphotons
sigmaDN = sigmaphotons/dn2photons
Fractional Method:Noise = dataL1.0 * sigmaDN/dataL0.5 in DN
secchi_prep Method:Noise = secchi_prep[sigmaDN]
Result= the same
5th SECCHI Consortium Meeting, May 5 2007Tomographic Reconstruction of CMEs from White Light Coronagraph Data
Solving (and LOS) Problems
Original Data, 45º apart
Rendered Solution
3-axis projection of solution datacube
Inverse modeling
5th SECCHI Consortium Meeting, May 5 2007Tomographic Reconstruction of CMEs from White Light Coronagraph Data
What is Pixon?(We interrupt for some definitions)
● "Data": 2-dimensional images, from a spacecraft or created via a
rendering of a model.
● "Image": a 3-dimensional data cube containing electron density
measurements. An image is rendered to produce data.
● Pixon: software using the PIXON algorithm for reconstruction.
"Classic" uses a cartesian grid, "Tetrahedral" uses an arbitrary grid.
● Raytrace WhiteLight, a renderer with front-end GUI.
5th SECCHI Consortium Meeting, May 5 2007Tomographic Reconstruction of CMEs from White Light Coronagraph Data
And Visualize!
(a busy IDL desktop)
● Row of images tv_multi,array_of_data
● Datacube axes threeview, imgcube
● Interactive 3-D GUI render_rot_gui,imgcube
5th SECCHI Consortium Meeting, May 5 2007Tomographic Reconstruction of CMEs from White Light Coronagraph Data
Sample 1: Chen Fluxrope Model
Model at 0º, 45º, 90º
Same, with noise added
5th SECCHI Consortium Meeting, May 5 2007Tomographic Reconstruction of CMEs from White Light Coronagraph Data
Fluxrope Reconstruction
Noisy model at 0º, 45º, 90º
Reconstruction at 0º, 45º, 90º
5th SECCHI Consortium Meeting, May 5 2007Tomographic Reconstruction of CMEs from White Light Coronagraph Data
Fluxrope Solution Densitycube
view down 'x' view down 'y' view down 'z'
Linear plot
Log plot
(Fit for 408 minutes, not to completion)
5th SECCHI Consortium Meeting, May 5 2007Tomographic Reconstruction of CMEs from White Light Coronagraph Data
Computational LimitsPrimary limit is memory, second is run-time.
Theory:●Typical 32-bit architecture can address 2GB of memory,
for 8 byte N3 arrays → N≤812.
Practice:●32-bit IDL can rarely allocate multiple large-N arrays: with 2GB RAM, IDL managed only (4) 5123 float arrays●Pixon uses N3 * 1.2×10-7 GB. N=512 → 16GB swap●RAM max space must be unfragmented, contiguous memory
Today:● Pixon N=256 runs (barely) with 2GB of physical RAM● Plan is to test N=512 on a 64-bit RAM=16MB system
5th SECCHI Consortium Meeting, May 5 2007Tomographic Reconstruction of CMEs from White Light Coronagraph Data
To Do
1) Complete testing, GUI
2) Reconstruction of A/B Cor2 + LASCO C2 CMEs
3) Reconstruction of A/B/LASCO events, multiple instruments
4) Reconstruction of an A/B HI CME (or comet?)
5) Higher resolution reconstructions (current limit, N=256)
6) Mix of inverse and forward methods
7) Commit software to SolarSoft archive
5th SECCHI Consortium Meeting, May 5 2007Tomographic Reconstruction of CMEs from White Light Coronagraph Data
Contact Info
Alex (Sandy) Antunes
http://ares.nrl.navy.mil /~antunes
5th SECCHI Consortium Meeting, May 5 2007Tomographic Reconstruction of CMEs from White Light Coronagraph Data