Magnetopause crossings during the 2019 dayside constellation

The two figures below show the relative timings of the Cluster spacecraft as they cross the magnetopause during the 2019 dayside constellation (November 2018 to July 2019) - the first figure shows inbound crossings whilst the second shows outbound crossings. The solid lines indicate the crossing times of the four spacecraft using the standard colour scheme: black for C1, red for C2, green for C3 and magenta for C4. All times are relative to the C1 crossing time, with positive times indicating a cross occurring before the C1 crossing time.

The grey dotted line indicates the crossing time for the centroid of all four Cluster spacecraft, which has traditionally been used by JSOC for targeting burst mode data-taking around magnetopause crossings. This targeting is probably not appropriate for the 2019 constellation.

During this constellation it may be better target burst mode data-taking on boundary crossings by the centroid of a subset of the four Cluster spacecraft. Some of those centroid crossing are shown in the figures below. Lists of some of these crossing are also available for download as Excel files - see the attachments to this page or the links below:

• ​Centroid of C2, C3 and C4

These figures are based on the long-term orbit data delivered by ESOC on 30 July 2018.

Inbound crossings

The figure below shows the relative timings of the inbound crossings of the Cluster spacecraft. Two additional lines have been included in the plot:

1. the bow shock crossing time of C1 is shown as a dashed black line. This highlights how there is a period (roughly 20 January to 14 April) when C3 and C4 are likely to cross the magnetopause whilst C1 is still in the solar wind and C2 is in the magnetosheath just outside the magnetopause.
2. the crossing time of the centroid of C3 and C4 is shown as a dashed light blue line.

Outbound crossings

The figure below shows the relative timings of the outbound crossings of the Cluster spacecraft. One additional line has been included in the plot:

1. the crossing time of the centroid of C2, C3 and C4 is shown as a dashed light blue line.