JOP159 CME's in Lyman-alpha Author: Chris St.Cyr, Eric Quemerais Received: May 20, 2002 Modified by SOCs: August 26, 2002 (added email list and other minor modifications based on meeting with JOP participants). Modified by SOCs: April 1, 2003 (added Stephane Ferron to the email list). Participants: SOHO/SWAN, SOHO/LASCO, SOHO/EIT, SOHO/UVCS Observation Period: April 25 indefinately Purpose: There is a possibility that SWAN may be able to detect CME's in Lyman-alpha that have been detected by LASCO in white-light. This is an important issue for forecasting geomagnetic storms because there are few methods of tracking CME's after they leave the coronagraph's field-of-view. During the months of June and July, the position of SOHO relative to the interstellar neutral Hydrogen flow provides a lower background for SWAN. SOHO is upwind from the Sun on June 6, which means that the circumsolar UV background comes from the downwind direction, i.e. the region which is depleted in netural H. A graphic showing the relative fields-of-view for SWAN and C3 is available at: ftp://stereo.gsfc.nasa.gov/pub/cstcyr/SOHO/SWAN/grid_ver2.pdf Observing Plans: The SWAN part of the observing campaign will run each week on Wednesdays from 18:00 UT to Thursdays at 10:00 UT and on Fridays from 11:20-24:00 UT. The UVCS observations will start about one day earlier. The default target will be on the west limb. If a very bright CME is observed on the east limb by LASCO and UVCS, the SWAN team will decide if they want to switch targets. It is possible that a sufficiently-bright CME could be detected in real-time by a LASCO or UVCS operations person. Given a speed through C3, one could estimate when the event would reach the SWAN field. If it were early in the EOF day and if real time commanding was available, then it is possible that Eric could interrupt whatever peogram was currently executing and reposition SWAN to try to detect the event. LASCO (Kevin Schenk) or the SOCs will notify the SWAN team by email whenever an especially "interesting" AR approaches the West limb. Such an AR would give a high probability of producing fast/bright CMEs during its west limb passage. The UVCS team routinely examines their data, so they may discover whether they captured a bright CME during the previous 24 hours. If a CME event is found having LyA intensity exceeding about 20 times the background corona, the UVCS team will report the time, height(s), position angle(s), estimate of the LyA line width and line-of-sight velocity of this CME to the JOP 159 mailing list. Depending on the specifics of the event based on LASCO and UVCS report, and the SWAN timeline, SWAN may still have the opportunity to change their pointing and attempt to observe it. In case UVCS is able to do dedicated CME watch one day before SWAN program for JOP 159 (i.e. on Tuesdays and Thursdays), UVCS will use a sit-and-stare program at 2.3 Ro. SWAN will observe above the limb (12 degrees above the west limb, TBD for the other limbs). LASCO will provide C3 clear filter clear polarizer full field of view images at a 30 minute cadence. EIT will provide 195A full field of view images at a 12 minute cadence. UVCS will probably use the CME sequence for the RHESSI campaign except it will emphasize Ly alpha at 2.3 R. Email list for JOP159 communications: SOC soc@soc.nascom.nasa.gov Eric Quemerais quemerai@aerov.jussieu.fr Stephane Ferron ferron@aerov.jussieu.fr Gareth Lawrence grl@kreutz.nascom.nasa.gov Kevin Schenk schenk@kreutz.nascom.nasa.gov Joe Gurman Gurman@gsfc.nasa.gov Chris StCyr cstcyr@grace.nascom.nasa.gov UVCS Planner planner@uvcs6.nascom.nasa.gov John Raymond raymond@cfa.harvard.edu NOTE: This JOP may later be expanded to include RHESSI and TRACE