SOHO Joint Operations Programme 87 ================================== CDS/TRACE - 18th May 1998 ------------------------- Active Region Loop Systems on the Limb -------------------------------------- H.E. Mason, C.D. Pike, P.R. Young and Ted Tarbell This study of active region loops is designed to follow a region as it goes around the limb - when individual loops stand out better against the background and so quantities such as electron density and temperature structure can be evaluated more easily as a function of height. The use of CDS density diagnostics (Si X 356.0/347.4 and Fe XIV 353.8/334.2 ratios) being ideal together with a range of lines formed at different temperatures. In addition, the high spatial resolution of the TRACE images will be used to determine the width of the loops and observe the loop rise (or fall) times. Several active region limb studies have already been carried out with CDS and these observations are producing some interesting results (Mason and Pike, 1997, Fludra et al, 1997). EIT movies have shown how dynamic active region loop systems are - the abilities of TRACE to achieve higher cadences and also to cycle through different filters easily, will allow loop evolution to be followed in greater detail than before. CDS has an excellent temperature discrimination, seeing many different coronal ions, and so will provide information on the relation between loops of different temperatures. CDS 1) An overview raster (LARGEBP2/v30, 4' x 4', 1hr 46 mins) 2) Repeats of a smaller raster (FFNARR30/v12, 1' x 3', 40 mins) 3) Another large raster (LARGE_T/v9, 4' x 4', 42 mins) Duration: 6-8 hours Suggested observing period: repeated as AR nears and transits around the limb. TRACE Contact: Ted Tarbell Suggested sequence(s): Cycle through Fe IX/X, Fe XII and Fe XV filters (around 1min. per cycle) ------- End of Forwarded Message