Anatomy of the Solar Ultraviolet Magnetograph Investigation Sounding Rocket
Abstract
A major focus of solar physics is to understand how the solar magnetic field stores and releases the energy that drives the dynamic phenomena of the outer atmosphere, namely flares and coronal mass ejections (CMEs). A crucial element in our current knowledge is how the field evolves as it changes from being pressure-dominated in the photosphere to being force-free in the corona. There have been ways to study the evolution indirectly by extrapolation or through morphology, but direct and quantitative measurements of magnetic field strength in the force-free corona is difficult and few attempts have ever been made. The Solar Ultraviolet Magnetograph Investigation (SUMI) sounding rocket has been developed by NASA Marshall Space and Flight Center (MSFC)and National Space and Science Center (NSSTC) to measure the linear and circular polarization of magnetically sensitive 280nm Mg II line and also to measure the circular polarization of the 155nm C IV emission lines originating in this force-free region. SUMI uses a Ritchey-Chretien telescope design with dielectric coating applied to the front surfaces of both telescope mirrors for the purpose of decreasing the thermal load. The out-of-band radiation is transmitted and then reflected out of the telescope. The polarimeter consists of a MgF2 rotatable waveplate and a double Wollaston polarizing beamsplitter. The waveplate is designed to measure the circular polarization at C IV (270° retardance at 155nm) and a full Stokes vector at Mg II (131° retardance at 280nm). SUMI measures both orthogonal polarizations in both C IV and Mg II simultaneously. Two toroidal varied-line-spacing (TVLS) grating are used, one for each polarization. There are two Mg II cameras, one for each polarization, and one C IV camera that captures both polarizations. All cameras use back- illuminated CCDs with measured quantum efficiency of more than 60%. SUMI is in the last stage of alignment and system testing and is expected to be launched in summer 2008. This SUMI result will be an essential complement to visible-light magnetographs for understanding how magnetic energy stored in a sheared field region is released in flares and CMEs. We will be describing the anatomy of the SUMI sounding rocket and the detector test and calibration program and the NASA/MFSC and NSSTC facilities where the instrument is being developed.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2008
- Bibcode:
- 2008AGUSMSP51B..01A
- Keywords:
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- 7500 SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7509 Corona