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M.J. Penn (CSUN/SFO)
From 15:33-16:02 UT on 13 June 1998 observations of an erupting filament as it crossed solar disk center were obtained with the NSO/KPVT and SoHO/CDS instruments as part of the SoHO Joint Observing Program 70. Context observations show that this event was the eruption of the north-east section of a small active region filament associated with NOAA~8237, that the photospheric magnetic field was changing in this active region from 12 through 14 June 1998, that a coronal Moreton-wave disk event occurred, as well as a white-light CME off the south-west solar limb.
The NSO/KPVT imaging spectroscopy sho the He~I 1083~nm absorption line blue-shifted to velocities of between 200 and 300~km~s-1. The true solar trajectory of the eruption is obtained by using the projected solar coordinates and by integrating the Doppler velocity. The filament travels with a total velocity of about 300~km~s-1 along a path inclined roughly 49 degrees to the solar surface and rises to a height of just over 1.5 solar radii. The KPVT data show no Stokes~V profiles in the Doppler shifted He~I 1083~nm absorption to a limit of roughly 3 \times 10-3 times the continuum intensity.
The SoHO/CDS data scanned the center of the KPVT FOV using seven EUV lines; Doppler shifted filament emission is seen in six lines from representing temperatures from about 2 \times 104K through 1 \times 106K. Bound-free continuum absorption from H~I, free from confusion from foreground emission and line emission, is seen as the filament obscures underlying chromospheric emission. A fit to the wavelength dependence of the absorption from five lines between 55.5 to 63.0~nm yields a column density \xiHI~=~1.7 \times 1018cm-2. Spatial maps show that this filament absorption is more confined than the regions which show emission.
This work was made possible by 1997 and 1999 SoHO Guest Investigator awards NASA #W-19,142 Basic and NASA NAG5-8004.
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The author(s) of this abstract have provided an email address for comments about the abstract: mpenn@akala.csun.edu