UGC 8331 has H I in one clump in the center and two clumps at larger radii,
making it impossible to measure the rotation curve.
DDO 169 (Fig. 22)-This system is also fairly well resolved but
exhibits a much more regular H I distribution than the ring of DDO 43.
The H I for DDO 169 is smoothly distributed, with a central
concentration and a slight "tail" trailing off to the southeast. During
the reduction of the data for this system, an H I companion was
detected, located about 2 kpc to the northwest of DDO 169. This
companion appears to have a very faint optical counterpart on the POSS
survey plate and is discussed in more detail in Appendix B. It should be
noted that the single-dish flux listed for DDO 169 in the RC3 includes
the H I mass of the companion as well. We have included only the
emission from DDO 169 itself in our calculations.
The velocity information for this galaxy, including the moderately
wide, slightly asymmetrical, Gaussian profile as well as the separated
isovels and shallow gradient of the first-moment map, show that it is
undergoing some modest rotation. The average velocity dispersion is also
moderate, at about 12 km s^-1^. The optical and H I images, however,
show that the optical emission extends farther to the northwest, in the
direction of the companion, than the H I distribution does. There are
two bright knots in the center of the optical image as well, one of
which appears to coincide with the peak in the H I distribution. The
extension of the H I to the southeast and the lack of H I to the
northwest are intriguing in light of the presence of the companion along
the same major axis. Further optical and H I observations of this system
are required for a more detailed study.
DDO 169: like DDO 168, one observes similar features in the surface
brightness and colour profiles. Extended "tail" towards the north. This
tail seems to be slightly bluer than the rest of the galaxy.
Ir IV-V or Ir V (DDO)