Direct Observations of the Magnetic Reconnection Site of an Eruption on 2003 November 18

We report direct observations of the magnetic reconnection site during an eruptive process that occurred on 2003 November 18. The event started with a rapid expansion of a few magnetic arcades located over the east limb of the Sun and developed an energetic partial-halo coronal mass ejection (CME), a long current sheet, and a group of bright flare loops in the wake of the CME. It was observed by several instruments, both in space and on the ground, including the EUV Imaging Telescope, Ultraviolet Coronagraph Spectrometer, and Large Angle Spectrometric Coronagraph experiment on board the Solar and Heliospheric Observatory, the Reuven Ramaty High Energy Solar Spectroscopic Imager, and the Mauna Loa Solar Observatory Mark IV K-Coronameter. We combine the data from these instruments to investigate various properties of the eruptive process, including those around the current sheet. The maximum velocities of the CME leading edge and the core were 1939 and 1484 km s^-1, respectively. The average reconnection inflow velocities near the current sheet over different time intervals ranged from 10.5 to 106 km s^-1, and the average outflow velocities ranged from 460 to 1075 km s^-1. This leads to a corresponding rate of reconnection in terms of the Alfvén Mach number M_A ranging from 0.01 to 0.23. The composite of images from different instruments specifies explicitly how the different objects developed by a single eruptive process are related to one another.