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Search: authors:"N. A. Tikhonov"

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CCD photometry and distances of six resolved irregular galaxies in Canes Venatici

The results of detailed imaging of six nearby irregular galaxies with radial velocities  km/s are presented. Except for one all the galaxies have been resolved into stars for the first time. Based on photometry of the brightest blue stars we derived the following distances to the galaxies: 3.6 Mpc for NGC 4163, 3.5 Mpc for NGC 4190, 8.6 Mpc for UGC 7298, 4.8 Mpc for UGC 7577, 3.7...

Optical monitoring of the z= 4.40 quasar Q 2203+292

We report Cousins R-band monitoring of the high-redshift (z= 4.40) radio-quiet quasar Q 2203+292 from 1999 May to 2007 October. The quasar shows maximum peak-to-peak light curve amplitude of ∼0.3 mag during the time of our monitoring, and ∼0.9 mag when combined with older literature data. The rms of a fit to the light curve with a constant is 0.08 and 0.2 mag, respectively. The...

Photometric distances to NGC 628 and its four companions

Based on photometry of the brightest blue stars we derived distance moduli for NGC 628 and its dwarf irregular companions: DDO 13, UGC 1171, UGC 1104, and K 10. The mean modulus of the group is estimated to be 29.46 mag with a formal (internal) error of 0.11. The total mass to luminosity ratio of 40 seems sufficient for NGC 628 to keep its companions in bound orbits.