Evidence that spectral differences observed among globular cluster giant stars with similar V and B-V values persist to fainter absolute magnitudes has been slowly accumulating in the past few years. In the case of 47 Tucanae, photometric evidence for CN strength variations extending to MV=1.5 mag was found from DDO photometry (Hesser, Hartwick and McClure 1976, 1977). Subsequently, CN strength variations at MV=+3.5, i.e., stars at the base of the vertical rise on the subgiant branch, were found by low dispersion spectroscopy (Hesser 1978). Kraft (1979) and collaborators have found evidence for star-to-star variations in NH and CH strengths among subgiant stars below the horizontal-branch level in the metal-poor cluster, M92; and Hesser and Harris (1979) have found CN and CH features to exhibit wide ranges among similar stars in M22, a metal-poor cluster with some apparent similarities to the otherwise uniquely anomalous cluster, Omega Centauri.

In the first program of direct photography with the 72-inch telescope of the Dominion Astrophysical Observatory, 1931–1934, the compact and distant globular cluster NGC 6934 in Delphinus was searched for variables for the first time by HSH. The 51 discovered were published in 1938 (Sawyer-Hogg 1938). From 1935 to 1964 the observational program was continued with the 74-inch telescope of the David Dunlap Observatory and a total of 161 plates was accumulated. In addition, six Mount Wilson plates from 1911 to 1917 were available to us.

Images of 68 globular clusters have been recorded in 125 exposures made with the electronic camera of the U.S. Naval Observatory on the 24-inch, 40-inch and 61-inch reflecting telescopes at the Flagstaff Station. The images were electronically malfocussed to allow the integration of light from the fainter cluster stars without saturation of the central portions of the brighter star images. Spacial information thus lost was partly regained by subsequent linear deconvolution of the cluster profiles by means of a star profile used as the point spread function.

There is spectroscopic evidence for initial abundance inhomogeneities from star to star within M13 and M22. Among three stars in M13, there is an order-of-magnitude range in the sodium-to-iron ratio, which lies well beyond all known random and systematic errors; details will be given in a paper in preparation. In M22, the spread discussed below in logarithmic iron-to-hydrogen ratios, [Fe/H], is 0.6 dex, which is far larger than that found here for any other globular cluster.

Scans have been made of ten BHB stars in the globular clusters M92, M13 and M5 and of eight stars in 1 HLF 2 with the multi-channel spectrometer on the Hale 5 meter telescope during July 1979. Twenty-four additional stars are being scanned at CTIO and KPNO using the Harvard scanner. Four-color observations were made of most of the BHB stars on the Steward Observatory 90″ telescope and these measures indicated that there were stars, at the same (b-y) color on the horizontal branch, with quite different values of the c1 index. The scans confirm these results, showing that the shape of the intensity vs wavelength curve for λ<4210 is related to the c1 index. These features are illustrated in the two figures, where it can be seen that a c1 value formed from the scans [(u-v)-(v-b)] is greater for the star in Figure 1.

The metallicities of the globular clusters 47 Tucanae, NGC3201, and NGC6752 have been determined from high dispersion spectra obtained with the echelle spectrograph at CTIO. The mean iron deficiencies of NGC3201 and NGC6752 are −1.0 and −1.3, respectively. Oxygen is enriched by a factor of two in NGC3201; no oxygen data are available in NGC6752 due to the small radial velocity of this cluster. The atmospheric parameters and the abundances, relative to the Sun, of individual elements for two stars in 47 Tuc are tabulated below. Star identifications are taken from Hesser and Hartwick (1977). The stellar effective temperatures were established from the spectroscopic data; the data do not permit temperatures much in excess of those quoted. Surface gravities were calculated from the cluster's distance modulus and other reasonably well-known quantities, with the assumption that the mass of a cluster giant is 0.8 M⊙.

Recently (Richer 1978, hereafter Paper I), the results of a search for faint blue objects in and around the globular cluster NGC 6752 were reported. The aim of the program was to isolate a sample of white dwarf candidates in this cluster which could then be studied in further detail. The statistics of this survey are as follows: (1) 68 objects found with B ≤ 22.7 and (U-B) ≤ −0.4 within 20 arcmin of the cluster center; (2) of the 68, 36 also had a measurable V magnitude; (3) of these 36, only 11 lay in the area of the color-color diagram occupied by white dwarfs, while the remaining 25 were generally well above the black body line and are probably QSOs or peculiar blue stellar objects; (4) of these 11, 7 are within 14 arcmin of the cluster center and hence have a probability of greater than 50% of being cluster members (King et al. 1968); (5) CTIO 4-m SIT vidicon spectra were obtained of 5 of these 7 candidates, 4 of which appear to be white dwarfs and 1 of which is a QSO with Z = 2. Table 1 lists the derived properties of the 4 white dwarfs assuming that they belong to NGC 6752. The star names are from Paper 1.

In his classical paper on violent relaxation, Lynden-Bell (1967) gave convincing but qualitative arguments for the approach of collisionless systems towards a stationary state and, applying the methods of equilibrium statistical mechanics to a coarse-grained description of the system, derived the equilibrium distribution attained. Here we report on a dynamical derivation of Lynden-Bell equilibrium, proceeding from the coarse-graining of the collisionless Boltzmann equation.

Two versions of the restrictions of the phase density are found and studied: when the integral equation for the phase density is reduced to the Abel equation. r1, λ and α or p are parameters of models. r1 is the radius of the model; -X is the energy integral; - a half of the angular momentum integral squared; φ(r) is the gravitational potential. The functions ψ(ξ) or f(u) are determined as solutions of the Abel equation, the given functions being the space density, ρ(r), or the potential, φ(r), known from observational data. The observational data have been approximated by two types of models: generalized Schuster models, or two-parametric generalized isochronous models, ρo or φo where ro or rh are scale parameters, β or q and c are structure parameters. Details of the report will be published in Publ. Tartu Astrophys. Obs.48, 1980 and in Astron. Zh. (Moscow)58, 1981.

A program to determine the axial ratios and major axis orientations for a sample of 120 galactic globular star clusters was begun by us recently. The sample was selected from the clusters listed by Kukarkin and which can be seen on the glass copies of the blue-emulsion plates of the Palomar Observatory Sky Survey and on the B-series film copies of the European Southern Observatory Sky Survey. Out of the major program will come axial-ratios of the elliptical isodensity contours for each cluster, as well as the orientations of the major axes of the elliptical contours, and an accurate position for the center of each of the clusters in the sample. The probable errors of the central coordinates will be on the order of ±1 arcsec or better.

Thirty-three globular clusters of our Galaxy were observed with the filters of the Vilnius photometric system UPXYZVS with 3450, 3740, 4050, 4660, 5160, 5440, 6550 å filters (Straižys 1977). For the classification of clusters in metallicities the reddening-free parameters QUYV QPYV and QXYV can be used. In Figure 1 these Q parameters, having a range of variation of the order of 0.4, are plotted against metallicity values from Kukarkin (1974). The parameter QPYZ has an even larger range of variation (of the order of 0.6). For determination of color excesses of clusters every color index can be used if its intrinsic values for a given metallicity defined by quantities Q are known (Figure 2). Average color excesses determined from the diagrams QUYV, (Y-V)o; QPYV, (Y-V)o and QXYV (Y-V)o and transformed to EB-V in Figure 3 are compared with color excesses from Kukarkin (1974). To summarize, the Vilnius system presents a number of metallicity sensitive, reddening-free parameters which can be used for [Fe/H] and color-excess determinations of globular clusters.