Magnetic field extrapolations:

• Target dates
• August 17, 1999 (MDI and Mees data available)
• August 19, 1999 (MDI and Huairou data available)
• August 21, 1999 (MDI, Mees, and Huairou data available)

• People involved
• Liu/Zhao/Hoeksema - MDI + Huairou data, will add on Mees data:  e.g. 8/19 nonlinear force free extrapolation: field + H-alpha, field + SXT, field at different angles
• Mikic/Linker -MDI + Mees data
• Mandrini/Schmieder - MDI data:  linear force free vs. potential field extrapolations:  e.g. 8/19 linear force-free; 8/19 potential; 8/21 linear force-free; 8/21 potential

 
• Plan of action: the three groups will independently model the same time periods.  If possible, the extrapolations should be done as near as is reasonable to the time of overlays (see below for August 19&21, and flare topology working group for optimal August 17 time(s)).

 
• Note: possible extension/comparison to Whole Sun Fortnight (WSM2) magnetic field observations, see proposed projects.

• Target dates and times
• ~ 14:05 UT, August 19, 1999 (mature filament)
• ~ 18:21 UT, August 21, 1999 (disappearing filament and brightening)
• prejet < 21:00, jet ~ 21:00-22:30 UT, August 26, 1999

• People involved
• MDI - Liu/Zhao/Hoeksema
• BBSO - Qiu
• SOON - Nitta
• CDS - Gibson/Mason/Pike
• TRACE - Fletcher
• EIT - Thompson
• Yohkoh SXT - Alexander
• MLSO Chip&Pics - Gibson/Burkepile/Gilbert/Holzer
• LASCO - Biesecker/St. Cyr

• Plan of action: Analysis and master overlays (for a single "snapshot" in time, 8/19, 8/21, 8/26) will be supervised by Gibson.  These will be interpreted together in context with the evolution of the sigmoid.

• Target date and time
• > 21:00 UT, August 26, 1999

• People involved
• CDS - Gibson/Mason/Pike/W. Thompson
• TRACE - Alexander/Fletcher
• EIT - B. Thompson
• Yohkoh SXT - Alexander
• MLSO Chip& dPmon (Pics)&Mk3/4 - Gibson/Burkepile/Gilbert/Holzer
• UVCS - Ko
• LASCO - St. Cyr/Biesec

 
• Plan of action:  Analysis led by Ko will consider dynamics, intensity, line shift vs. height and time.

• Target dates
• August 19, 1999 (mature filament)
• August 21, 1999 (disappearing filament and brightening)
• August 26, 1999 (jet)

 
• People involved
• CDS - Del Zanna/Gibson/Mason/Pike
• UVCS - Ko

 
• Plan of action:  Analysis be led by Del Zanna will calculate densities/temperatures across sigmoid on the disk and where possible at the limb.  Questions to be addressed: Is there a cavity surrounding sigmoid? Is the sigmoidal core hotter/cooler than its surroundings? How does the temperature/density vary with height?  The information from these line ratio diagnostics will be compared to that of multi-instrument overlays.

• Global field - effect of the sigmoid evolution on the global field
• Target dates: August 17, 19, 21 to correspond to extrapolations of sigmoid field
• People involved: Sigmoid field extrapolators as above, also Mikic/Linker and Hoeksema for time-dependent global field analysis

• August 17, 1999 NE streamer eruption - connection between sigmoid flaring and polar crown filament eruption, and also to any corresponding CME, IPS, and solar wind measurements