Note on tracking Sun-Earth connection event

ICME Event: 2011/05/28

Observer: Eleni Nikou on 2019/05

1. ICME
  1.1. Catalog
     # Identified in ICME catalogs: Richardson & Can List
      RC catalog:
      Disturbance start time: 2011/05/28 01:00 UT
      Ejecta      Start time: 2011/05/28 05:00 UT
      Ejecta      End   time: 2011/05/28 21:00 UT
      dv = 60 km/s, v = 540 km/s, vmax= 540 km/s
      MC index:     2
      Dst:        -80 nT
      Suggested source CME: 2011/05/25 04:20 UT
      V_transit:  450 km/s
      
  1.2. Comments
      Overall ICME quality index: 1
      ICME signatures: Bmax: 13.5 nT
                       Bz rotation, smooth increase of u, Tp<Texp, low beta, sharp decrease of n around 10:00 UT 2011/05/28

      Disturbance time 510 km/s  -> search window 3-4 days -> 2011/05/25

2. CME
   2.1. A. Candidate A
    A.1. LASCO:    
      #CME 2011/05/25 around 05:24 UT, seems like a very faint partial halo at the southern hemisphere (CDAW gives it as a very poor event)
          
    A.2 .STEREO: 
           CME in COR2-A and COR2 B (COR2-A first appearence at 05:24 UT)
	   Front-side halo CME, consistent witht the flare source region, close to the disc center as seem from AIA

    A.3. AIA & GOES
	   corresponding flare: B1.9 at 2011/05/25 03:41 UT
	                        flare from AR11218 at the southern western hemisphere

    A.4 Comment:  
	   Could be the source. The orientation of the partial halo CME and the CME as observed by COR2 match the observations on the disc.
   


    2.2. A. Candidate B
    A.1. LASCO:    
      #CME 2011/05/25 around 13:25 UT, seems like a faint partial halo towards the nothern hemisphere (CDAW gives it as a very poor event)
          
    A.2 .STEREO: 
           CME in COR2-A and COR2 B (COR2-A first appearence at 13:24 UT)
	   Front-side halo CME, consistent witht the flare source region, close to the disc center as seem from AIA

    A.3. AIA & GOES
	   GOES does not give a flare at that time, but if we look at the AIA data there is activity from AR11218 and it is moving NW, which is in agreement with the orientation of the partial halo

    A.4 Comment:  
	   The orientation of the partial halo CME and the CME as observed by COR2 match the observations on the disc. Since the orientation of B is towards the NW it likely not earth directed.
     
   2.3. Comment
    Most likely the source region is candidate A.
  

3. Other Comments
   Both candidates had small dimmings. 

4. Summary
    SW index 1
    Source index 3
    Overall index 3