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$\begin{figure} \par\includegraphics[width=17.65cm,clip]{8902fig1.eps}\end{figure}$ Figure 1: Azimuthal renormalised frames of 6 of 8 observations in the U band of comet C/2004 Q2 (Machholz) on 2005 Jan. 12, together with three observations of the night before ( upper left), and one on the night after ( lower right). The trails on the images are due to background stars and indicate the comet's motion. All images taken on the 12th show clear ion rays, while on the 11th, only the typical sharp ion tail is visible; no ion rays appear. In the right lowerhand corner, it is clear that the ion rays gradually disappear. All images have the same scale and color coding, the direction of the Sun is upwards, and the field of view radius is approximately 4.3 $\times$ 10⁴ km.
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In the text

$\begin{figure} \par\includegraphics[width=8.5cm,clip]{8902fig2.eps}\end{figure}$ Figure 2: Polar representation of images taken 2005 Jan. 12 at 22:50 and 23:06 UT. The comet's nucleus is to the right. In the upper section of both images, two ion rays are visible (indicated by tickmarks). These rays are folding along the tail's axis with an angular velocity of $\sim$ 0.9 degrees per minute.
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In the text

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{8902fig3.eps}\end{figure}$ Figure 3: Upper panel: measurements of the solar wind velocity from SOHO/CELIAS (black line) and a corotational mapping (red line) at the location of C/2004 Q2 (Machholz). Middle panel: the proton flux from SOHO/CELIAS Proton Monitor at L1. The solar event on 12 January was due to a CIR, which is typically preceded by a sudden peak in the proton flux. Lower panel: ratio of ${\rm O}^{7+}/{\rm O}^{6+}$ from ACE/SWICS. The red line represents the results from an empirically deduced formula (Zurbuchen & Richardson 2006), for which a low value (horizontal red line) indicates a fast, cold solar wind. The vertical black line denotes the first observation on 12 January.
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In the text

$\begin{figure} \par\includegraphics[width=5.55cm,clip]{8902fig4.eps}\end{figure}$ Figure 4: Configuration of C/2004 Q2 (Machholz), the Earth, and Sun on 2005 Jan. 12, when the solar wind regime changes suddenly from slow to fast, and ion folding rays are visible. All orbits are seen from above and projected onto the ecliptic. Note that Machholz' orbit has an inclination of $\sim$ 39 deg with respect to the ecliptic (data from http://ssd.jpl.nasa.gov/horizons.cgi).
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In the text

$\begin{figure} \par\includegraphics[width=8.5cm,clip]{8902fig2.eps}\end{figure}$	Figure 2: Polar representation of images taken 2005 Jan. 12 at 22:50 and 23:06 UT. The comet's nucleus is to the right. In the upper section of both images, two ion rays are visible (indicated by tickmarks). These rays are folding along the tail's axis with an angular velocity of $\sim$ 0.9 degrees per minute.
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$\begin{figure} \par\includegraphics[width=5.55cm,clip]{8902fig4.eps}\end{figure}$	Figure 4: Configuration of C/2004 Q2 (Machholz), the Earth, and Sun on 2005 Jan. 12, when the solar wind regime changes suddenly from slow to fast, and ion folding rays are visible. All orbits are seen from above and projected onto the ecliptic. Note that Machholz' orbit has an inclination of $\sim$ 39 deg with respect to the ecliptic (data from http://ssd.jpl.nasa.gov/horizons.cgi).
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