Table 1:

Four Stokes parameter spectropolarimetric observations of  CVn used for Magnetic Doppler Imaging.

UT Date	Stokes			JD (2 450 000+)					S/N
	Parameters			Q	U	V			range
18 Feb. 1997	Q	U	V	498.511	498.531	498.489	0.038	0.004	420-550
19 Feb. 1997	Q	U	V	499.532	499.555	499.511	0.225	0.004	650-690
20 Feb. 1997a			V			500.422	0.387		550
21 Feb. 1997	Q	U	V	501.490	501.504	501.470	0.582	0.003	270-320
22 Feb. 1997	Q		V	502.549		502.519	0.773	0.003	320-490
23 Feb. 1997	Q	U	V	503.497	503.516	503.474	0.949	0.004	240-280
25 Feb. 1997b			V			505.581	0.331		470
25 Feb. 1997	Q	U		505.695	505.715		0.353	0.002	410-410
07 Feb. 1998	Q	U	V	852.562	852.584	852.539	0.771	0.004	740-890
09 Feb. 1998	Q	U	V	854.561	854.584	854.539	0.137	0.004	820-1020
11 Feb. 1998	Q	U	V	856.545	856.567	856.524	0.499	0.004	910-1020
12 Feb. 1998	Q	U	V	857.675	857.694	857.657	0.706	0.003	820-880
13 Feb. 1998	Q	U	V	858.555	858.574	858.537	0.867	0.003	710-810
15 Feb. 1998	Q	U	V	860.605	860.626	860.586	0.242	0.004	500-720
16 Feb. 1998	Q	U	V	861.606	861.627	861.584	0.424	0.004	560-750
17 Feb. 1998	Q	U	V	862.533	862.554	862.515	0.594	0.004	560-560
19 Feb. 1998	Q	U	V	864.603	864.638	864.576	0.973	0.006	430-590
15 Jan. 1999	Q		V	1194.621		1194.600	0.310	0.002	400-450
19 Jan. 1999	Q	U	V	1198.652	1198.672	1198.633	0.049	0.004	770-840
26 Jul. 2004	Q	U	V	3213.362	3213.381	3213.400	0.413	0.004	440-480

Notes. Columns give the UT date for the beginning of the night when observation was obtained, the Stokes parameters observed (in addition to Stokes I), the Julian Dates of mid-exposure for each observed Stokes parameter, the mean phase for all observed Stokes parameters, the maximum difference between and the phases of individual Stokes parameter observations, the range of the signal-to-noise ratio per 2.6 km s^-1 spectral pixel for two or three exposures.
^(a) The Stokes Q and U spectra are disregarded. See text for detailed explanation. ^(b) The Stokes V observation is considered individually due to a larger-than-average phase difference with respect to the linear polarization spectra obtained on that night.