Using long-slit spectra centered in wavelength about H alpha, we have obtained a velocity map of a 20" x 140" east-west box centered on the nuclear region of M101. The velocity resolution is 2.5 km s(-1) and the spatial resolution is approximately 1" east-west and variable (3"-4" on average) north-south. We have also obtained temperature, density, and shock maps of the same region using the [N II] lambda 6548, [N II] lambda 6583, H alpha, [S II] lambda 6717, and [S II] lambda 6731 lines. The temperatures range from 4100 to 14,100 K, with an intensity-averaged temperature of 6200 K. The densities range from 6.6 to 36,600 cm(-3), with an intensity-averaged density of 800 cm(-3). Regions northeast and southwest of the nucleus have [N II] lambda 6583/H alpha ratios greater than or similar to 0.56 and [S II] lambda lambda(6717 + 6731)/H alpha ratios greater than or equal to 0.4, which are indicative of shock-heated or power-law photoionized gas. The gas in an S-shaped region passing through the nucleus has [N II] lambda 6583/H alpha ratios less than or similar to 0.56 and [S II] lambda lambda(6717 + 6731)/H alpha ratios of approximate to 0.1, which is representative of gas in H II regions. The velocity data are consistent with gas infalling toward the nucleus as part of streaming motions traveling west to east on the north side of the nucleus and east to west on the south side of the nucleus. However, there appears to be a local instability in which the motion southwest of the nucleus is moving west to east, creating a collision of the two opposing gas motions in a region of relatively high density and temperature. A blue are emanating from an unresolved source on or near the nucleus shows evidence of collision in this same high-density, high-temperature region. Our data support a previous conclusion that M101 may be considered an intermediate galaxy with respect to activity, possibly in transition between a normal nucleus and a more active stage.

We have embarked on a long term project to obtain high precision photometry on individual galaxies in 45 rich clusters of galaxies. Data from the first set of six clusters have yielded BVRI photometric information on 961 galaxies and 384 stars. These objects come from the central one Mpc of Abell 576, 957, 1185, 1377, 2063, and 2657, each of which is of richness class R greater than or equal to 1. Each object was examined with two radial surface brightness fitting functions, and an asymptotic magnitude was determined. One fitting function produced a shape parameter beta which, when taken in. combination with the color index (B-I), shows a breakdown of the three basic morphological types (E, S0, and S) into four beta types and a set of peculiar galaxies. Our results match previous studies well, and also provide some new insights into the clusters. In addition, we have examined the effects of plate scale on the determination of these photometric parameters. All parameters were found to repeat across plate scale differences. We also examined the effects of co-adding frames in an attempt to understand the degradation or improvement of the photometric parameters with increasing signal-to-noise. (C) 1997 American Astronomical Society.

A high galactic latitude nebula, Lynds Bright Nebula 434, was found to lie over part of the rich cluster of galaxies Abell 2657 [Hintz et al. AJ (submitted) (1997)]. To examine the effects of this nebula upon the cluster we have mapped the excited gas and dust in the region of the cluster using an H alpha filter and CCD. Additionally, UBVR observations were taken to estimate the reddening in this region. Using late-type stars in the field of the cluster we found a maximum E(B - V) value of 0.(m)35 within the visible nebulosity. We show that this amount of reddening is sufficient to cause the effects on the luminosity function of Abell 2657 detailed in Hintz ct al. (1997). In addition, we estimate that the nebula is approximately 250 pc in distance and has a physical diameter of about 7 pc. (C) 1997 American Astronomical Society.

We report the discovery of a faint carbon star, designated CV 5, located at galactic latitude +81 degrees. Eight angstrom resolution optical spectra show C-2 bandheads at lambda 4737, lambda 5165, lambda 5635, and lambda 6191 Angstrom although the latter bandhead is harder to identify because of blending. Spectral indices indicate that it possesses a temperature of approximately 2600 degrees K and an extremely high carbon abundance. Its proper motion was measured and an upper limit of 0.025 ''/yr was found. Although a lambda 6191 Angstrom bandhead as strong as is observed in this star is indicative of dwarf carbon star, the small proper motion causes us to conclude that CV 5 is most likely a halo giant. (C) 1997 American Astronomical Society.