New dwarfs around the curly spiral galaxy M63
  We present a deep (50 hours exposed) image of the nearby spiral galaxy M 63
(NGC 5055), taken with a 0.14-m aperture telescope. The galaxy halo exhibits
the known very faint system of stellar streams extending across 110 kpc. We
found 5 very low-surface-brightness dwarf galaxies around M 63. Assuming they
are satellites of M 63, their median parameters are: absolute $B$-magnitude
-8.8 mag, linear diameter 1.3 kpc, surface brightness $\sim$ 27.8 mag/sq.
arcsec and linear projected separation 93 kpc. Based on four brighter
satellites with measured radial velocities, we derived a low orbital mass
estimate of M 63 to be (5.1$\pm$1.8) 10$^{11} M_{\odot}$ on a scale of
$\sim$216 kpc. The specific property of M 63 is its declining rotation curve.
Taking into account the declining rotation curves of the M 63 and three nearby
massive galaxies NGC 2683, NGC 2903, NGC 3521, we recognize their low mean
orbital mass-to-K-band luminosity ratio, (4.8$\pm$1.1) $M_{\odot}/L_{\odot}$,
that is only $\sim$1/6 of the corresponding ratio for the Milky Way and M 31.
