MLSO Mark-III K-Coronameter
Coronal Mass Ejection

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29 December 1997 . . . Day of year: 363

Direct ImageSubtraction Image
[Direct Image] [Subt. Image]
18:09 UT18:09 minus 17:51

Event Information

Event Description

This is another event best viewed through the subtraction images. The event is visible in MK3 beginning around 17:56 UT and remains visible through the LASCO C3 field of view until 22:45 UT. A frontal LOOP and CAVITY feature could be discerned in all datasets used (MK3, LASCO C2 and C3), but a core feature could only be identifed in the MK3 field of view. The loop and cavity were measured out to 9.4 solar radii and 5.1 solar radii respectively. It is interesting to note that when looking at the plotted trajectory points, the fit for both the loop and cavity might have been better suited to a third- order, non-constant acceleration fit. The loop and cavity seemed to exhibit a deceleration in the LASCO C2 field of view.

There are two CME's visible on this day in LASCO. The first to appear is very close to PA 270. The LASCO event corresponding to this MK3 event appears at roughtly 19:17 in C2 and has a higher PA, closer to 290 degrees. Here are the LASCO notes. describing this event.

There is a MK3 direct-image movie [GIF, 1091K] and a MK3 subtraction movie [GIF, 383K] to view for this event.

There is also a LASCO C2 movie [MPEG, 397 KB] and a LASCO C3 movie [MPEG, 616 KB] of this event as well.

Event Properties

There were a total of 40 data points obtained for use in trajectory fits. Of those, 18 were for the outer loop, 17 for the cavity, and 5 for the core feature.
The event times were from 17:56UT until 22:45UT . The event was visible in MK3 and continued past the LASCO C3 field of view. 

Central Position Angle:   ~300 - Loop	
   (in degrees)		  ~300 - Cavity 
			  ~300 - Core 	


Width (degrees): 	  ~13  - Loop   (MK3) 
			  ~ 9  - Cavity (MK3) 
			  ~ 5  - Core   (MK3)
The following data is obtained from performing a second order, least squares fit of the trajectory data points (Hundhausen, et al, 1994) : 
Start Times (UT):	  17:45:02 - Loop    
			  17:36:12 - Cavity  
			  18:00:51 - Core    

Start Heights (Solar Radii):   1.0 - Loop  
			       1.0 - Cavity 
			       1.4 - Core  

Final Speeds (km/s):	     322.3 - Loop   
			     160.1 - Cavity 
			      75.9 - Core    (Only 5 datapts)
				

Accelerations (km/s^2):	     -0.01    - Loop   
			     -0.0005  - Cavity 
			      0.05    - Core   (Only 5 datapts)
The above numbers were produced from a second-order fit of trajectory data which began in MK3 and ended in LASCO C3. Estimated start times, start heights, final speeds and accelerations are available in each individual data set (MK3, C2, and C3) where enough data points were available. That information is not presented here. Final speeds were evaluated at last data point in C3 except where noted.

Image Gallery

A gallery of the `best' direct and the `best' subtraction images (`display' version) from this event may be accessed below.

Be aware that these are only a few of the images that you may access. For a complete list of images, including the `computational' versions, please visit our FTP site.

All times are given in Universal Time (UT) units.

Best MK3 Direct Images

MK3 movie [GIF, 1091 KB]

MK3 images :

Best MK3 Subtraction Images

MK3 subtraction movie [GIF, 383 KB]

MK3 images :

References 

Hundhausen, A.J., J.T. Burkepile, and O.C. St.Cyr,
  Speeds of coronal mass ejections:  SMM Observations
  from 1980 and 1984-1989,
  J. Geophys. Res., 99, 6543-6552, 1994.

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