View of the three CMEs fronts 22 hours after the launch of the first ejection by the two Heliospheric Imagers 1 instruments.
The three front edges are visible in the two STEREO/HI1 field-of-views.


View of the three CMEs fronts 25 hours after the launch of the first ejection by the two Heliospheric Imagers 1 instruments.
The first two front edges are in the process of merging in HI1-B field-of-view.


View of the three CMEs fronts 22 hours after the launch of the first ejection by the two Heliospheric Imagers 2 instruments.
Note the brightness increase at the back of the first front edge in the STEREO/HI2-B image.
This is again due to the overtaking of the first CME by the second one.


View of the three CMEs fronts 28 hours after the launch of the first ejection by the two Heliospheric Imagers 2 instruments.
In the STEREO/HI2-B image, the first two front edges have fully merged, whereas in the STEREO/HI2-A image, they are still distinguishable.
This illustrates the different speeds of propagation of the ejections in different quadrants of the heliosphere.


View of the three CMEs fronts 34 hours after the launch of the first ejection by the two Heliospheric Imagers 2 instruments.
The first two front edges are in the process of merging in the STEREO/HI2-A image.

Note about the images:
For the STEREO/Heliospheric Imagers 1 images, what is shown is the ratio of two images separated by one hour (normal output frequency of the instrument).
For the STEREO/Heliospheric Imagers 2 images, what is shown is the ratio of two images separated by three hours.