Note on tracking Sun-Earth connection event

ICME Event: 2011/09/17

Observer: Eleni Nikou on 2019/06

1. ICME
  1.1. Catalog
     # Identified in ICME catalogs: Richardson & Can List
      RC catalog:
      Disturbance start time: 2011/09/17 03:43 UT
      Ejecta      Start time: 2011/09/17 14:00 UT
      Ejecta      End   time: 2011/09/18 06:00 UT
      dv = 70 km/s, v = 430 km/s, vmax= 590 km/s
      MC index:     2
      Dst:        -72 nT
      Suggested source CME: 2011/09/13 22:10 UT
      V_transit:  540 km/s
      
  1.2. Comments
      Overall ICME quality index: 2
      ICME signatures: Bmax: 14.5 nT
               ICME signatures: B decreases smoothly after 22:00 UT, u decreases smoothly until 00:00 UT, low beta, Tp<Texp

      Disturbance time 430 km/s  -> search window 4 days -> 2011/09/13-14

2. CME
   2.1. A. Candidate A
    A.1. LASCO:    
      #CME 2011/09/14 00:00:05 UT, partial halo CME, (CDAW)
           

    A.2 .STEREO: 
           Also seen as a CME in COR2-A and COR2 B (first frame at COR2-A 23:54 UT, 2011/09/13)
	   Front-side CME

    A.3. AIA & GOES   
	   corresponding flare: C2.9 at 2011/09/13 23:31 UT
	                        flare from AR11295 at N22E62

    A.4 Comment:  
	   Could be the source: The timing and orientation is in agreement with the observations.
   
       We see dimmings at the southern part of the active region. The nothern part is covered by flare brightenings.


   2.1, B, Candidate B
     B.1. LASCO  
       #CME 2011/09/14 20:12:05 UT, partial halo CME (CDAW)
           

     B.2. STEREO
         front-side CME, (first frame at COR2-A 20:54 UT)

     B.3. AIA & GOES 
          #GOES flare C9.2,  14-Sep-2011 20:42 UT from AR11297, S18W48

	      The active region is on the southern western hemisphere and it is constistent with the observations. It is detected by STA first.

     B.3. Comment
          Could be the source: The timing and orientation is in agreement with the observations

2.1, C, Candidate C
     C.1. LASCO  
       #CME 2011/09/15 00:00:06 UT, partial halo CME (CDAW)
           

     C.2. STEREO
         front-side CME, (first frame at COR2-A 00:24 UT)

     C.3. AIA & GOES 
          #GOES flare C4.6, 15-Sep-2011 00:24 UT, AR11297, S18W50

	      The active region is on the southern western hemisphere and it is constistent with the observations. It is detected by STA first.

     C.3. Comment
          The orientation is in agreement with the observations, but it is unlike that this is the source because of the timing. Based on the transit velocity the CME needs more that 2 days to arrive to Earth.
  
  
   2.2. Comment
        
    Very small - negligible dimming area.




3. Other Comments

     CDAW gives a partial halo CME at 12:36:06 UT, 2011/09/13, but it is a back-side event.

     The source is likely Candidate A because of the velocity and timing data. It is slightly faster than Candidate B and if we take into account that Candidate B occured almost 20 hours after Candidate A, it makes it a possible source.

4. Summary
    SW index 2
    Source index 2
    Overall index 2