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.

The hk index has been used as a metallicity indicator for RR Lyrae variable stars. It is now being applied to the shorter period δ Scuti variables. Employing spectroscopic abundances of stars with published hk values and photometric indices calculated from stellar atmosphere models, a three-dimensional interpolation is used to determine [Fe/H] from intrinsic b-y, c₁, and hk values. The resulting [Fe/H], log g, and T_eff values for 10 δ Scuti stars are presented.

We report initial results from a project to design an interactive on-line data archive for short-period variable stars. Our goal is to provide an easily accessible set of web pages for use by a researcher at the telescope. The first step is to provide the researcher with convenient access to data archives for a variety of short-period variable stars. In addition to the basic data archive, there is a page for each star that contains positional information, the most recent epoch and period data, basic physical parameters, and a set of helpful journal references. We also include a page for each of the program variables with a finder chart and a selection of comparison stars for use in differential photometry. Additionally, one entry point in the system is a phase calculator that will sort through the data and return a list of stars that are observable from various user input locations during a variety of time periods. The current system has a partial data set in place for over one hundred short-period variable stars. We intend to continue to expand this set to include a large number of complete data files. We are also considering a similar archive of galaxy images for comparison use in student conducted supernova searches. We find this system improves the scientific return form our two small telescopes at the West Mountain Observatory. We believe this model can also be employed to optimize data management and scientific return for a wide variety of projects from the new generation of large ground-based telescopes.

New photometric (uvby beta) observations of V1162 Orionis are reported. We derive a reddening value of E(b - y) = 0.021 mag and a metallicity of [Fe/H] = +0.1. Intrinsic (b - y) and c(1) values indicate a mean effective temperature, [T-eff] = 7540 K, and a mean surface gravity, [log g] = 3.96. Theoretical evolutionary tracks, along with pulsation models, indicate the mass of V1162 Ori is 1.8 M. and the age is 0.60 Gyr. New V magnitude CCD observations are also reported. A time of maximum light analysis shows that V1162 Ori has experienced a period break. In addition, the amplitude has dropped from Delta V = 0.2 before the period break to Delta V = 0.1 after the break.

We report 15 new times of maximum light for the delta Scuti star IP Virginis (formerly known as SA 106-1024). An analysis of all times of maximum light indicates that IP Vir has been decreasing in period at a constant rate of -7.4 x 10(-9) days day(-1). Evidence is also presented that IP Vir is a double-mode variable with a period ratio of pi(1)/pi(0), = 0.774. This period ratio predicts a [Fe/H] value of -0.3. From photometric (uvby beta) observations, we find a foreground reddening of E(b - y) = 0.008 mag and a metallicity of [Fe/H] = +0.05. It is shown that [Fe/H] = -0.3 is most likely the correct value. Intrinsic (b - y)- and c(1)-values, plotted in a model atmosphere grid, indicate a mean effective temperature, [T-eff] = 7400 K, and a mean surface gravity, [log g] = 3.89. All of these physical parameters support Landolt's initial conclusion that IP Vir is an ordinary delta Sct star.

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.