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Session 1 - Chromosphere, Corona, Flares.
Display session, Friday, June 27
Ballroom B, Chair: Charles Kankelborg

[1.27] Continuous Observations of Solar Magnetic Fields from SOI/MDI on SOHO

J. T. Hoeksema, R. I. Bush, P. H. Scherrer (W.W. Hansen Experimental Physics Laboratory, Stanford University), C. Heck, N. Hurlburt, R. Shine, T. Tarbell, A. Title (Lockheed Martin Palo Alto Research Laboratory)

The Solar Oscillations Investigation's Michelson Doppler Imager instrument (SOI/MDI) on SOHO measures the photospheric magnetic field over the whole disk nearly every 96 minutes with 4" resolution and a noise level of a few Gauss. Beginning in April 1996, this unprecedented continuous series of frequent, uniform quality magnetograms provides a striking view of the continual emergence, motion, evolution, and interaction of magnetic flux everywhere on the visible solar surface near solar minimum. These evolving photospheric fields ultimately drive the variations of the corona and solar wind that affect the terrestrial environment. Knowledge of the rapidly evolving photospheric field provides a crucial input for forecasting conditions in the corona, heliosphere, and geospace.

A few magnetograms are available each day within hours of observation through the SOHO web site at These may be used for planning and forecasting, e.g. to compute models of the solar corona. The remainder are generally available within a few weeks. Sometimes more focused campaigns provide magnetic observations as often as once each minute for up to 8 hours. Campaigns can be run with either the full disk resolution or with 0.6" pixels in a limited field near the center of the disk. The SOI project welcomes collaborations. More information can be found at

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Program listing for Friday