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We present  UBVR  C  I  C  magnitudes of 49 comparison stars in the fields of the Seyfert galaxies Mrk 335, Mrk 79, Mrk 279, Mrk 506, 3C 382, 3C 390.3, NGC 6814, Mrk 304, Ark 564, and NGC 7469 in order to facilitate the photometric monitoring of these objects; 36 of the stars have not been calibrated before. The comparison stars are situated in 5 × 5 arcmin fields centred on the Seyfert galaxies, their  V  band flux ranges from 11.7 to 18.2 mag with a median value of 16.3 mag, and their  B  –  V  colour index ranges from 0.4 to 1.6 mag with a median value of 0.8 mag. The median errors of the calibrated  UBVR  C  I  C  magnitudes are 0.08, 0.04, 0.03, 0.04, and 0.06 mag, respectively. Comparison stars were calibrated for the first time in three of the fields (Mrk 506, 3C 382, and Mrk 304). The comparison sequences in the other fields were improved in various aspects. Extra stars were calibrated in four fields (Mrk 335, Mrk 79, NGC 6814, and NGC 7469) – most of these stars are fainter and are situated closer to the Seyfert galaxies compared to the existing comparison stars. The passband coverage of the sequences in five fields (Mrk 335, Mrk 79, Mrk 279, NGC 6814, and Ark 564) was complemented with the  U  band. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Johnson‐Cousins magnitudes of comparison stars in the fields of ten Seyfert galaxies