Astron. Astrophys. 324, 457-460 (1997)

1. Introduction

Following the program of measurement of distances to nearby galaxies with radial velocities km/s (Karachentsev, 1994), we present here an estimate of photometric distance to the galaxy NGC 6503. According to the Reference catalogue (de Vaucouleurs et al., 1991 = RC3) this spiral of Sc type has a total apparent magnitude , and a standard angular diameter arcmin. In spite of the low value of the measured radial velocity, +25 km/s (Begeman, 1987), the galaxy still remains without a direct distance estimate.

Like NGC 1156 (Karachentsev et al., 1996), NGC 6503 is one of the most spatially isolated galaxies in the Local universe. It is in the Catalog of Isolated Galaxies by Karachentseva (1973). Peebles (1990) notes that two bright spirals, NGC 6503 and NGC 6946, are situated inside the so called "Local Void" that occupies a volume of Mpc in diameter (Tully, 1988). According to Peebles, such very isolated galaxies may have an unusual structure and peculiar velocity. However, the observations of NGC 6503 in HI and lines (van Moorsel & Wells, 1985, Weavers et al., 1986, Begeman, 1987, Karachentsev & Petit, 1990) reveal no significant anomalies of its kinematics and structure as compared to other spiral galaxies. It is interesting to point out that a special survey undertaken on POSS-II films by Karachentseva & Karachentsev (1997) led to the discovery of three dwarf galaxies which turned out to be physical companions of the spiral NGC 6946 (Huchtmeier et al., 1997). However, the same survey finds no companions around NGC 6503 except for one faint object (1754.4 +7008) with unknown radial velocity.

© European Southern Observatory (ESO) 1997

Online publication: May 26, 1998

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