MLSO Mark-III K-Coronameter
Coronal Mass Ejection

<HR size=6

24 February 1998 . . . Day of year: 55

Direct ImageSubtraction Image
[Direct Image] [Subt. Image]
18:00 UT18:00 minus 17:40

Event Information

Event Description

This event became visible in the MK3 instrument at around 17:48 UT and left at approximately 18:09 UT. The event was travelling southward throughout the MK3 measurements, explaining the large difference in position angle of the beginning of the event from the end.

The event became visible in the LASCO C2 field of view at approximately 18:27 UT (at least that was the first C2 image available for measurements.) The outer loop feature became distorted here and it became difficult to identify a cavity feature. For this reason, there are no cavity measurements in the LASCO C2 fields of view. The event was not really visible in the C3 field of view.

Here are the preliminary LASCO notes for this event. There were two events visible on this day in C2, the first one is a very bright event on the eastern limb early in the day. The second, and the one corresponding to this MK3 event, was observed later in the day on the west limb.

There is a MK3 direct-image movie [GIF, 964K] and a MK3 subtraction movie [GIF, 854K] to view for this event.

There is also a LASCO C2 movie [MPEG, 323 KB] of this event.

Event Properties

There were a total of 28 data points obtained for use in trajectory fits. Of those, 12 were for the outer loop, 7 for the cavity, and 9 for the core feature.
The event times were from 17:48UT until 20:55 UT. The event was visible in MK3 and continued past the LASCO C2 field of view. 

Central Position Angle:   ~265 - Loop	
   (in degrees)		  ~265 - Cavity 
			  ~260 - Core 	


Width (degrees): 	  ~43  - Loop   (MK3) 
			  ~21  - Cavity (MK3) 
			  ~11  - 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):	  17:35:05 - Loop    
			  17:38:16 - Cavity  
			  17:39:57 - Core    

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

Final Speeds (km/s):	     248.5 - Loop    (out to C2)
			     313.1 - Cavity  (out to C2)
			     224.5 - Core    (out to C2)
				

Accelerations (km/s^2):	     -0.05  - Loop    
			      0.03  - Cavity  
			      0.03  - Core
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.

Trajectory Plots

(Click on plots to see full size)
First OrderSecond Order
(Loop, Cavity, & Core) (Loop, Cavity & Core)
[First Order Fit] [Second Order Fit]
MK3 and C2 MK3 and C2

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, 964 KB]

MK3 images :

Best MK3 Subtraction Images

MK3 movie [GIF, 854 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.

Authors:
Web Editor:

Return to the MLSO CME home page

<HR size=6