All Figures

Figure 1: H2CO energy level diagram up to 40 K above the ground state. Note the "K-doublets'' in the ladder, that are the result of the slight asymmetry of the molecule. For the six observed transitions that are marked by arrows (two J=2-1 ortho-H2CO rotational transitions, one J=1-0 and one J=2-1 para-H2CO rotational transition and the J=1 and 2 K-doublet ortho-H2CO transitions), rest frequencies are given.

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In the text

Figure 2: VLA A-array continuum images of B0218+357 taken at Q-, U-, and X-band ( top to bottom). In each image, the lowest contour line represents four times the rms noise level, which is , 2.1, and 0.5 mJy beam-1 for the Q-, U-, and X-band images, respectively. Contour levels increase by a factor of 4 for the Q-band image and by a factor of 2 for the U- and the X-band images. Peak flux densities are 0.267, 0.99, and 1.0 Jy beam-1. The full width to half maximum dimensions of the restoring beam are shown in the lower left corner of each panel. The origin of each image is the phase center position given in Sect. 2.1.

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In the text

	Figure 3: H2CO lines observed toward B0218+357 and Gaussian fits. Given are line-to-continuum ratios (the entire continuum flux of B0218+357 was taken) as a function of heliocentric velocity adopting a redshift of z=0.68466. The labels in the lower left corner of each spectrum show transition and rest frequency. O and P refer to ortho- and para-H2CO, respectively.
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In the text