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We describe deep (40 orbits) Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph observations of the broad absorption line (BAL) quasi-stellar object (QSO) PG 0946+301 and make them available to the community. These observations are the major part of a multiwavelength campaign on this object aimed at determining the ionization equilibrium and abundances (IEAs) in BALQSOs. We present simple template fits to the entire data set, which yield firm identifications for more than two dozen BALs from 18 ions and give lower limits for the ionic column densities. We find that the outflow's metallicity is consistent with being solar, while the abundance ratio of phosphorus to other metals is at least 10 times solar. These findings are based on diagnostics that are not sensitive to saturation and partial covering effects in the BALs, which considerably weakened previous claims for enhanced metallicity. Ample evidence for these effects is seen in the spectrum. We also discuss several options for extracting tighter IEA constraints in future analyses and present the significant temporal changes that are detected between these spectra and those taken by the HST Faint Object Spectrograph in 1992.

We have discovered a remarkable quasar, FIRST J101614.3+520916, whose optical spectrum shows unambiguous broad absorption features, while its double-lobed radio morphology and luminosity clearly indicate a classic Fanaroff-Riley type II radio source. Its radio luminosity places it at the extreme of the recently established class of radio-loud broad absorption line quasars. Because of its hybrid nature we speculate that FIRST J101614.3+520916 is a typical FR II quasar that has been rejuvenated as a broad absorption line (BAL) quasar with a compact steep spectrum core. The direction of the jet axis of FIRST J101614.3+520916 can be estimated from its radio structure and optical brightness, indicating that we are viewing the system at a viewing angle of [?]40deg. The position angles of the radio jet and optical polarization are not well aligned, differing by ~20deg-30deg. When combined with the evidence presented by Becker and coworkers for a sample of 29 BAL quasars showing that at least some BAL quasars are viewed along the jet axis, the implication is that no preferred viewing orientation is necessary to observe BAL systems in a quasar's spectrum. This, and the probable young nature of compact steep spectrum sources, leads naturally to the alternate hypothesis that BALs are an early stage in the lives of quasars.

A sample of 4208 objects with magnitude 15 < g* < 22 and colors of main-sequence A stars have been selected from 370 deg2 of Sloan Digital Sky Survey (SDSS) commissioning observations. The data is from two long, narrow stripes, each with an opening angle of greater than 60deg, at Galactic latitudes 36deg < |b| < 63deg on the celestial equator. Relative photometric calibrations good to 2% and consistent absolute photometry allows this uniform sample to be treated statistically over the large area. An examination of the sample's distribution shows that these stars trace considerable substructure in the halo. Large overdensities of A-colored stars in the north at (l, b, R) = (350deg, 50deg, 46 kpc) and in the south at (157, -58, 33 kpc) and extending over tens of degrees are present in the halo of the Milky Way. Ivezic et al. have detected the northern structure from a sample of RR Lyrae stars in the SDSS. Using photometry to separate the stars by surface gravity, both structures are shown to contain a sequence of low surface gravity stars consistent with identification as a blue horizontal branch (BHB). Both structures also contain a population of high surface gravity stars 2 mag fainter than the BHB stars, consistent with their identification as blue stragglers (BSs). The majority of the high surface gravity stars in the Galactic halo may be BS stars like these. A population of F stars associated with the A star excess in the southern structure is detected (the F stars in the northern structure at 46 kpc would be too faint for the SDSS to detect). From the numbers of detected BHB stars, lower limits to the implied mass of the structures are 6 x 106 M and 2 x 106 M, although one does not yet know the full spatial extent of the structures. The fact that two such large clumps have been detected in a survey of only 1% of the sky indicates that such structures are not uncommon in the halo. Simple spheroidal parameters are fit to a complete sample of the remaining unclumped BHB stars and yield (at r < 40 kpc) a fit to a halo distribution with flattening (c/a = 0.65 +- 0.2) and a density falloff exponent of a = -3.2 +- 0.3.

We find that the depth and shape of the broad absorption lines (BALs) in BALQSO 1603+3002 are determined largely by the fraction of the emitting source which is covered by the BAL flow. In addition, the observed depth of the BALs is poorly correlated with their real optical depth. The implication of this result is that abundance studies based on direct extraction of column densities from the depth of the absorption troughs are unreliable. Our conclusion is based on analysis of unblended absorption features of two lines from the same ion (in this case the Si IV doublet), which allows unambiguous separation of covering factor and optical depth effects. The complex morphology of the covering factor as a function of velocity suggests that the BALs are produced by several physically separated outflows. The covering factor is ion dependent in both depth and velocity width. We also find evidence that in BALQSO 1603+3002 the flow does not cover the broad emission line region.