摘要：Using Hubble Space Telescope imaging of the resolved stellar population of KK 242 = NGC 6503-d1 =PGC 4689184, we measure the distance to the galaxy to be 6.46 ± 0.32 Mpc and find that KK 242 is a satellite of the low-mass spiral galaxy NGC 6503 located on the edge of the Local Void. Observations with the Karl G. Jansky Very Large Array show signs of a very faint H i signal at the position of KK 242 within a velocity range of Vhel = −80 ± 10 km s−1. This velocity range is severely contaminated by H i emission from the Milky Way and from NGC 6503. The dwarf galaxy is classified as the transition type, dIrr/dSph, with a total H i mass of < 106M⊙ and a star formation rate SFR(Hα) = −4.82 dex (M⊙ yr−1). Being at a projected separation of 31 kpc with a radial velocity difference of—105 km s−1 relative to NGC 6503, KK 242 gives an estimate of the halo mass of the spiral galaxy to be ) = 11.6. Besides NGC 6503, there are eight more detached low-luminosity spiral galaxies in the Local Volume: M33, NGC 2403, NGC 7793, NGC 1313, NGC 4236, NGC 5068, NGC 4656, and NGC 7640, from whose small satellites we have estimated the average total mass of the host galaxies and their average total mass-to-K-band-luminosity 〈MT/M⊙〉 = (3.46 ± 0.84) × 1011 and (58 ± 19)M⊙/L⊙, respectively.
