Forecasting the in situ properties of coronal mass ejections (CMEs) from remote images is expected to strongly enhance predictions of space weather, and is of general interest for studying the interaction of CMEs with planetary environments. We study
the feasibility of using a single heliospheric imager (HI) instrument, imaging the solar wind density from the Sun to 1 AU, for connecting remote images to in situ observations of CMEs. We compare the predictions of speed and arrival time for 22 CMEs (in 2008-2012) to the corresponding interplanetary coronal mass ejection (ICME) parameters at in situ observatories (STEREO PLASTIC/IMPACT, Wind SWE/MFI). The list consists of front- and backsided, slow and fast CMEs (up to $2700 : km : s^{-1}$). We track the CMEs to $34.9 pm 7.1$ degrees elongation from the Sun with J-maps constructed using the SATPLOT tool, resulting in prediction lead times of $-26.4 pm 15.3$ hours. The geometrical models we use assume different CME front shapes (Fixed-$Phi$, Harmonic Mean, Self-Similar Expansion), and constant CME speed and direction. We find no significant superiority in the predictive capability of any of the three methods. The absolute difference between predicted and observed ICME arrival times is $8.1 pm 6.3$ hours ($rms$ value of 10.9h). Speeds are consistent to within $284 pm 288 : km : s^{-1}$. Empirical corrections to the predictions enhance their performance for the arrival times to $6.1 pm 5.0$ hours ($rms$ value of 7.9h), and for the speeds to $53 pm 50 : km : s^{-1}$. These results are important for Solar Orbiter and a space weather mission positioned away from the Sun-Earth line.
A filament eruption, accompanied by a B9.5 flare, coronal dimming and an EUV wave, was observed by the Solar TERrestrial Relations Observatory (STEREO) on 19 May 2007, beginning at about 13:00 UT. Here, we use observations from the SECCHI/EUVI telesc
opes and other solar observations to analyze the behavior and geometry of the filament before and during the eruption. At this time, STEREO A and B were separated by about 8.5 degrees, sufficient to determine the three-dimensional structure of the filament using stereoscopy. The filament could be followed in SECCHI/EUVI 304 A stereoscopic data from about 12 hours before to about 2 hours after the eruption, allowing us to determine the 3D trajectory of the erupting filament. From the 3D reconstructions of the filament and the chromospheric ribbons in the early stage of the eruption, simultaneous heating of both the rising filamentary material and the chromosphere directly below is observed, consistent with an eruption resulting from magnetic reconnection below the filament. Comparisons of the filament during eruption in 304 A and Halpha show that when it becomes emissive in He II, it tends to disappear in Halpha, indicating that the disappearance probably results from heating or motion, not loss, of filamentary material.
