We present multi-point in situ observations of a complex sequence of coronal
mass ejections (CMEs) which may serve as a benchmark event for numerical and
empirical space weather prediction models. On 2010 August 1, instruments on
various space missions (Solar Dynamics Observatory/ Solar and Heliospheric
Observatory/Solar-TErrestrial-RElations-Observatory) monitored several CMEs
originating within tens of degrees from solar disk center. We compare their
imprints on four widely separated locations, spanning 120 degree in
heliospheric longitude, with radial distances from the Sun ranging from
MESSENGER (0.38 AU) to Venus Express (VEX, at 0.72 AU) to Wind, ACE and ARTEMIS
near Earth, and STEREO-B close to 1 AU. Calculating shock and flux rope
parameters at each location points to a non-spherical shape of the shock, and
shows the global configuration of the interplanetary coronal mass ejections
(ICMEs), which have interacted, but do not seem to have merged. VEX and
STEREO-B observed similar magnetic flux ropes (MFRs), in contrast to structures
at Wind. The geomagnetic storm was intense, reaching two minima in the Dst
index (~ -100 nT), caused by the sheath region behind the shock and one of two
observed MFRs. MESSENGER received a glancing blow of the ICMEs, and the events
missed STEREO-A entirely. The observations demonstrate how sympathetic solar
eruptions may immerse at least 1/3 of the heliosphere in the ecliptic with
their distinct plasma and magnetic field signatures. We also emphasize the
difficulties in linking the local views derived from single-spacecraft
observations to a consistent global picture, pointing to possible alterations
from the classical picture of ICMEs.
