RHESSI Working Group 4, GSFC meeting June 20, 2002

Fletcher: introductory comments

  * group membership, adding Amir, Steven, Ed Schmahl, Ken Phillips
  * Where we're at. Where are we?
    - Footpoints; still active
    - RHESSI/CDS; still active (Peter G on March 26 event)
    - Plasma diagnostics in looptop; morphed to include Fe feature (Ken)

    - April 21: energetics
    - April 21: mass chain (Gopal not available) - ?
    - April 21: origin of non-thermal particles   
  * Discussion of SXI availability; workshop Aug. 19-20 in Boulder
  * Event list
    - May 29 2003
    - April 21 again
    - Jan 24 2003 02:40 (SXI)
    - Mar 26 2002 (C3)
    - Jul 17 02 07:00
    - Mar 14 02 01:50
    - Sep  9 02
    - May 27 02
    - Mar 15 02 
    - Feb 26 02 10:20

Ji: Collaborating with RHESSI in H-alpha blue wing

  * Tasks (why the blue wing? See Gayley thesis; recent Ding paper)
  * May 27, 2002 18:00: kernel emissions may lag HXR
  * Stationary reconnection point? Looptop source? Nice filament
    eruption associated with HXR and EUV 
    - substantial discussion of geometry and interpretation; no cartoon
  * Very high deceleration speed of filament - 10g => tension force
  * Corrected quicklook plots
  * Conclusions - confined "thermal" event. stationary reconnection. no
    opening field. tension force. Halpha blue not like HXR. post-flre
    loop
  * Vigorous discussion of many points. This flare is a nice example of
    a "frustrated eruption" (Rust), something that seems to happen
    fairly commonly for events below X class. The Neupert effect seems
    a bit anomalous, to the extent that the odd term "thermal flare" has
    been used.
  * September 9, 2002 17:00 
  * Conjugate light curves can be found
  * Suggest 0.5-sec delay between H-alpha footpoints @ 40 msec sampling;
    these results can be criticized as overinterpretation (Dennis)
  * Discussion points to the need for better time-series analysis,
    including better RHESSI light curves
  * Another footpoint pair suggests several-second delay =>
    overinterpretation
  * Summary: different heating mechanisms for conjugate footpoints?
    Suggest propagation "braking" effect? Again much discussion,
    including the topic of whether the HXR footpoint asymmetry result is
    a valid one

White: liaison between WG 3 and WG 4

  * WG 3 has no prepared presentations
  * OVRO event list in the making
  * Radio spectral index comparison, to be discussed Saturday morning 
  * Microflares/type IIIs

Fletcher

  * How are we to proceed? Individual events vs survey?
    - continue investigating individual flares in depth
    - making lists of events in broad categories
    - providing information to one another about individual events
    - more quantitative approach to correlations
  * Broad event categories
    - Failed filament eruptions
    - successful filament eruptions
    - confined flares
    - microflares
  * Flare properties 
    - moving footpoints
    - moving looptop sources
    - preflare coronal sources

============ coffee break ==============

Gallagher

  * CDS March 26 event: 5 min cadence with excellent morphology in
    five bands plus TRACE
  * Pixon maps post impulsive phase; spectrum of loop top with nice Fe
    feature
    - discussion of Pixon behavior (Metcalf)
    - discussion of what is real and what is not real - "if you are
      interested in extended sources, you should not use high resolution
      collimators"
  * Cooling sequence via time delays, conductive or radiative?
  * Is there multi-thread structure? Laplacian filtering of post-flare
    loop image [Note that laplacian.pro has disappeared from SolarSoft!]
  * Nice movie and flow plots (120 km/s) suggest filament-like flows
    associated with the impulsive phase of the flare, emanating from
    near one footpoint but perhaps consistent with a coronal origin.
  * Strong emerging-flux signatures
  * Interesting dimming properties? But no obvious CME-type expansions
    in the TRACE images. Spine-type geometry?
  * "Certainly the best CDS..." flare event?

Gallagher

  * April 21 CME/flare
  * Discussion of how we identify features between different wavelengths
    (obnoxious Hudson comments)
  * HVT with RHESSI spectral separation
  * Forbes-Priest cartoon made glorious - not ready for prime time?
  
Dennis
  * RHESSI view of Ji's first event, 27-May-02
  * G4-only analysis separates Fe from Fe-Ni peak? Huge pulse pileup and
    neat tidy decimation signatures
  * Is there another example of an early non-thermal phase here?