All Figures

$\begin{figure} \par\includegraphics[width=8cm,clip]{3716fig1.eps} \end{figure}$ Figure 1: Relations between the heliocentric and cloud-centred frames used to describe the Solar System scanning geometry for a mission like PLANCK. The relations between Planck, Sun, Cloud Center and the observed portion of cloud are drawn, the L₂ point is not drawn to simplify the graph. The connection between the other two reference frames is shown in Fig. 2. An example of scan circle and the related spin axis, $\hat{\vec{S}}$ , are also drawn. The graph is not in scale with real distances. (Colour figure in the electronic version.)
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In the text

$\begin{figure} \par\includegraphics[width=7.3cm,clip]{3716fig2a.eps}\par\includegraphics[width=7.8cm,clip]{3716fig2b.eps} \end{figure}$ Figure 2: Relations between the cloud-centred ecliptic reference frame, the cloud symmetry reference frame and the spacecraft centred corotating reference frame. Top panel: angles between the cloud-centred Ecliptical reference frame (full yellow disc (light-gray in the bw version) - black arrows), and the cloud cylindrical symmetry reference frame (dashed blue disc - red arrows). Bottom panel: angles between the cloud cylindrical symmetry reference frame, the cloud-centred corotating cylindrical reference frame, the spacecraft - centred corotating reference frame. The displacement of PLANCK (in this case above the symmetry plane), $\delta \vec{R}_{{\rm P}}$ , respect to the constant reference position, $\overline{\vec{R}}_{{\rm P}}$ , assumed to be in the symmetry plane of the corotating reference frame is also displayed. The graph is not in scale with real distances. (Colour figure in the electronic version.)
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In the text

$\begin{figure} \par\includegraphics[angle=90,width=8.6cm,clip]{3716fig3.eps} \end{figure}$ Figure 3: Simulated contour plot of $Z_f(\mbox{$\vec{P}$ })$ [MJy/sr] for a fixed location within the Solar System. Contours are calculated for Z_f = 0.205, 0.22, 0.23, 0.24 MJy/sr and from 0.25 MJy/sr up to 3.2 MJy/sr in steps of 0.05 MJy/sr. Surface brightnesses exceeding 3.2 MJy/sr occurring in the central empty region have been neglected. The blue-dotted line represents the path of a scan circle of PLANCK for an horn located at the centre of the field of view while the gray band represents the PLANCK field of view. The vertical axis is the latitude over the ecliptic. The horizontal axis the longitude relative to the solar direction (opposite to orientation of the scan axis). Note that in this case the symmetry plane of the IDP cloud is below the ecliptic plane. (Colour figure in the electronic version.)
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In the text

$\begin{figure} \par\includegraphics[angle=90,width=7cm,clip]{3716fig4.eps} \end{figure}$ Figure 4: Simulated data stream of surface brightnesses (MJy/sr) measured at 857 GHz for the ZLE - smooth component (red), the Galaxy (green) and the sum of the two (blue). The ordinate is the phase of the scan circle, assumed to be zero for the pointing direction nearest to the North ecliptic Pole. Two subsequent scan circles are displayed, the phase of the second being augmented of $360^\circ$ . The lowest, full, cyan line (peaks at 0.1 MJy/sr) represents the contribution of secondary components of the ZLE. The red-dashed line represents the full contribution of ZLE with both smooth component and secondary components. The cyan band represents the uncertainty in the prediction for the Smooth component due to the uncertainty in the extrapolated E_f value in the case of $m_{\rm c} \protect\ga 10^{-6}$ gr. Both the dashed line and the cyan band are reported after adding the Galactic contribution as a green dashed line and a grey band above the Galaxy. (Colour figure in the electronic version.)
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In the text

$\begin{figure} \par\hspace*{0.5mm}\includegraphics[angle=90,width=7.35cm,clip]{3... ...ce*{3mm} \includegraphics[angle=90,width=7.45cm,clip]{3716fig5c.ps} \end{figure}$ Figure 5: Relative contribution of ZLE, Galactic (dust) emission and noise as a function of the pointing ecliptical longitude at three PLANCK frequency bands: 857 GHz ( top), 545 GHz ( middle), 343 GHz ( bottom). For each pointing ecliptical longitude, the plots gaves the ratio of the ZLE over the Galactic emission $\mbox{$E_f$ }Z_f/G_f$ averaged over the given scan circle (white - full line), the $\pm$ $3\sigma$ range (blue (black in the bw version) band), the peak ratio (yellow (gray) - full line) and the averaged ratio between the instrumental noise and the Galactic emission. Data are calculated for patches of $1^\circ$ in radius, noise is for a 14 month mission (2 sky surveys). (Colour figure in the electronic version.)
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In the text

$\begin{figure} \par\includegraphics[angle=90,width=8.4cm,clip]{3716fig6.eps} \end{figure}$ Figure 6: Derivatives of $Z_{{\rm Smooth}, 857~{\rm GHz}}$ along (blue full line - $\delta _\parallel$ ) and across (red dashed line - $\delta _\perp$ ) the scan circle of Fig. 3. For graphical reasons derivatives in the plot are scaled by a factor 10³. According to the convention of Fig. 4 the phase represents the pointing position along the scan circle, with 0 for the pointing direction nearest to the North ecliptical Pole. Note that the $\delta _\perp$ direction is always normal to $\delta _\parallel$ and oriented toward the local solar direction so that ${\rm d}\ln Z_f/{\rm d} ~\delta_\perp$ is always positive. (Colour figure in the electronic version.)
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In the text

$\begin{figure} \par\includegraphics[angle=90,width=7.9cm,clip]{3716fig7.ps} \end{figure}$ Figure 7: Absolute and relative variation of the ZLE surface brightness during the year at 857 GHz. The full-red line (light-gray in bw) is the yearly averaged ZLE surface brightness [MJy/sr] for a given eclipitical latitude. The surrounding green band (dark-gray in bw) is the variation of ZLE surface brightness during the year. Below (full black lines) the relative variation (with respect to the average) of ZLE for a set of representative longitudes (from the left of the black curves, from $0^\circ$ to $75^\circ$ in steps of $15^\circ$ , respectively from top to bottom). Note that these relative variations reach peaks of $\simeq$ $10\%$ . Data are calculated for patches of $1^\circ$ in radius, $E_{857~{\rm GHz}} = 0.65$ .
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In the text

$\begin{figure} \par\includegraphics[angle=90,width=8cm,clip]{3716fig8.ps} \end{figure}$ Figure 8: Seasonal modulation of the Smooth component of the ZLE at 857 GHz for four selected pointing directions: the North ecliptic Pole (N), the South eclitptic Pole (S), the Forward direction with respect to the PLANCK motion (FW) and the Backward direction (BW). Longitudes are relative to the longitude of the ascending node. Upper frame: the surface brightness variation looking to N (full line), S (long dashed line), FW (short dashed line), BW (dot-dashed line). The variation is the difference between the surface brightness along the direction of choice and its yearly average. Here $E_{{\rm Smooth}, ~857~{\rm GHz}} = 0.65$ . Lower frame: North-South (full line) and Forward-Backward (dashed line) asymmetries. Asymmetries are defined as A = 2(F₂ - F₁)/(F₂ + F₁) with $F_2 = F_{{\rm N}}$ , $F_1 = F_{{\rm S}}$ for the North-South asymmetry and $F_2 = F_{{\rm FW}}$ , $F_1 = F_{{\rm BW}}$ in the other case.
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In the text

$\begin{figure} \par\includegraphics[angle=90,width=8.4cm,clip]{3716fig9.ps} \end{figure}$ Figure 9: Deviation of the ZLE from an f² scaling as a function of the direction in the sky. Upper frame: the original data for f = 100, 143, 217, 353, 545, 857 GHz (from lower to upper surface brightness). Lower frame: deviation from the f² scaling in terms of $2-\gamma _{f,z}$ , where $\gamma _{f,z}$ is obtained by fitting a power law scaling on the data in the upper frame. In the horizontal axis we report the pixel indices for an HEALPix map with $\mbox{$N_{{\rm side}}$ }= 16$ ordered according to the ring scheme. The colatitude in the map decreases from left to right. (Colour figure in the electronic version.)
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In the text

$\begin{figure} \par\includegraphics[width=8.5cm,clip]{3716fig10.eps} \end{figure}$ Figure 10: Map of $\bar{Z}_{{\rm Smooth}, \; 857~{\rm GHz}}$ with $\mbox{$N_{{\rm side}}$ }= 128$ . The top of the map corresponds to the direction of the anticenter of the cloud. The sides and the middle of the map to poiting directions in the cloud symmetry plane. Compared to Fig. 3, the circles phase is $0^\circ$ when the pointing direction lies on the equator near $X_{{\rm corot}}$ and $90^\circ$ on the equator near $Y_{{\rm corot}}$ (the North pole of the cloud). (Colour figure in the electronic version.)
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In the text

$\begin{figure} \par\includegraphics[angle=90,width=8.65cm,clip]{3716fig11.ps} \end{figure}$ Figure 11: Differential surface brightness of the ZLE from the Smooth component in the 857 GHz channel, $\mbox{$E_f$ }= 0.65$ calculated for a spacecraft ecliptical longitudes 77.7 $^\circ$ (solid line), 122.7 $^\circ$ (dotted line), 167.7 $^\circ$ (dashed line), 212.7 $^\circ$ (dash dot line), 257.7 $^\circ$ (long dashed line), 302.7 $^\circ$ (solid thick line), 347.7 $^\circ$ (dotted thick line), 392.7 $^\circ$ (dashed thick line). The ascending node of the symmetry plane for the Smooth component cloud is assumed to be at a longitude of 77.7 $^\circ$ , so that these longitudes are equivalent to an angular distance of 0 $^\circ$ , 45 $^\circ$ , 90 $^\circ$ , 135 $^\circ$ , 180 $^\circ$ , 225 $^\circ$ , 270 $^\circ$ , 315 $^\circ$ from the node respectively. The surface brightness scale is in units of MJy/sr. The yellow (light-gray in bw) band represents the $5\sigma$ sensitivity (white noise limited) expected from PLANCK in the 857 GHz frequency channel for circular patches of $2^\circ$ of radius. (Colour figure in the electronic version.)
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In the text

$\begin{figure} \par\includegraphics[width=8.5cm,clip]{3716fig12.ps} \end{figure}$ Figure 12: Effect of the random relative calibration error on the E_f determination with the differential method at 857 GHz for 2 $^\circ$ patch, as a function of the cut on the Galactic surface brightness, and assuming a random relative calibration error with null expectation and rms per patch of $1\%$ . The full line represented the expected bias in the E_f determination. The dashed lines delimit the $1\sigma$ expected variability, both expectation and rms are calculated over 3 $\times$ 10⁴ Monte Carlo realizations. For surface brightnesses >10 MJy/sr the rms of the error decreases decreasing the accepted surface brightness, at lower surface brightnesses this is no longer true due to the reduction in statistics.
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In the text