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Arctic cyclones are key drivers of sea ice and ocean variability. During the 2019–2020 Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition, joint observations of the coupled air‐ice‐ocean system were collected at multiple spatial scales. Here, we present observations of a strong mid‐winter cyclone that impacted the MOSAiC site as it drifted in the central Arctic pack ice. The sea ice dynamical response showed spatial structure at the scale of the evolving and translating cyclonic wind field. Internal ice stress and ocean stress play significant roles, resulting in timing offsets between the atmospheric forcing and the ice response and post‐cyclone inertial ringing in the ice and ocean. Ice motion in response to the wind field then forces the upper ocean currents through frictional drag. The strongest impacts to the sea ice and ocean from the passing cyclone occur as a result of the surface impacts of a strong atmospheric low‐level jet (LLJ) behind the trailing cold front and changing wind directions between the warm‐sector LLJ and post cold‐frontal LLJ. Impacts of the cyclone are prolonged through the coupled ice‐ocean inertial response. Local impacts of the approximately 120 km wide LLJ occur over a 12 hr period or less and at scales of a kilometer to a few tens of kilometers, meaning that these impacts occur at combined smaller spatial scales and faster time scales than most satellite observations and coupled Earth system models can resolve. Arctic winter cyclones are an important part of the Arctic climate system. Yet, due to sparse observations, processes of the coupled sea ice‐ocean response to cyclones are not fully understood. During the 2019–2020 Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition, observations of the atmosphere, sea ice, and ocean were collected at a range of spatial scales. Here, we describe the atmospheric structure and coupled ice‐ocean response to a strong winter cyclone using data from surface weather stations, weather balloons, radar, and a weather model. We then describe the sea ice motion using a large set of global positioning system buoys and ice radar images. Finally, we examine the upper ocean currents and structure using ocean buoy data. The most important part of the storm structure for the sea ice is the development of an atmospheric low‐level jet (LLJ), a narrow region of fast‐moving air that eventually circles around the storm. The sudden change in ice drift speed at the time that the LLJ passes overhead enhances motion of the ice and ocean. Periodic currents in the ocean initiated by the sudden wind change of the LLJ continue for days following the passage of the storm, prolonging its effects. A strong cyclone crossed the Multidisciplinary drifting Observatory for the Study of the Arctic Climate (MOSAiC) in midwinter 2020Detailed, multi‐platform observations enable characterization of coupled air‐ice‐ocean interactions during the passage of the cycloneThe development of a low‐level atmospheric jet is a key factor in the spatially and temporally varying sea ice‐ocean response to the storm A strong cyclone crossed the Multidisciplinary drifting Observatory for the Study of the Arctic Climate (MOSAiC) in midwinter 2020 Detailed, multi‐platform observations enable characterization of coupled air‐ice‐ocean interactions during the passage of the cyclone The development of a low‐level atmospheric jet is a key factor in the spatially and temporally varying sea ice‐ocean response to the storm

Dissolved organic matter (DOM) absorption and fluorescence properties were investigated for seawater samples collected from the polar mixed layer (0–30 m) of the Canada Basin in 2010–2012. Sea ice concentration as well as fractions of meteoric and sea ice meltwater (fMWand fSIM) calculated from oxygen isotope ratio (δ18O) were applied to assess the importance of discrete freshwater inputs to the distribution of DOM. Parallel factor analysis identified four humic‐like (C1‐2 and C4‐C5) and one protein‐like (C3) fluorescent components in 380 excitation‐emission matrix spectra. Surprisingly, despite different sea ice cover and biological regimes, DOM composition was largely homogeneous spanning these annual surveys. A strong and reoccurring coastal influence on DOM absorption and humic‐like DOM was observed each year and was particularly pronounced during the summer 2011 survey. Enrichment of DOM humic signal (C1, C2, and C4) in brine‐rich (fSIM< 0) waters relative to sea ice melt‐dominated waters (fSIM> 0; p< 0.05) was found during 2011 and 2012 in the offshore region (>76°N) where coastal influences were minimal (fMW< 0.1). Similar fSIM< 0 were found for 2011 and 2012, either when considering the Canada Basin as a whole or the offshore region (>76°N) exclusively, which could imply that brine formation influenced humic signals in polar mixed layer seawater. Findings herein highlight that future projected changes in freshwater sources and brine production in the Canada Basin will likely implicate the distribution and composition of DOM. In this paper we showed that despite different sea ice cover in summer‐early fall, the average levels and composition of colored dissolved organic matter remained relatively unchanged in surface waters in the Canada Basin in 2010–2012. Only the northwest region experiencing strong brine rejection showed elevated humic signals. We also suggest to use the 140°W line as reference for dissolved organic matter monitoring in the Canada Basin in future studies. The absorption and fluorescing characteristics of DOM were relatively homogenous in the Canada Basin in summer/early fall 2010–2012The humic‐like components were more abundant in the brine‐rich mixed layerThe 140°W line is proposed for monitoring DOM compositional changes in the Canada Basin

High latitude warming and permafrost thaw will expose vast stores of deep soil organic carbon (SOC) to decomposition. Thaw also changes water movement causing either wetter or drier soil. The fate of deep SOC under different thaw and moisture conditions is unclear. We measured weekly growing‐season δ13C of ecosystem respiration (Recoδ13C) across thaw and moisture conditions (Shallow‐Dry; Deep‐Dry; Deep‐Wet) in a soil warming manipulation. Deep SOC loss was inferred from known δ13C signatures of plant shoot, root, surface soil, and deep soil respiration. In addition, a 2‐year‐old vegetation removal treatment (No Veg) was used to isolate surface and deep SOC decomposition contributions to Reco. In No Veg, seasonal Recoδ13C indicated that deep SOC loss increased as the soil column thawed, while in vegetated areas, root contributions appeared to dominate Reco. The Recoδ13C differences between Shallow‐Dry and Deep‐Dry were significant but surprisingly small. This most likely suggests that, under dry conditions, soil warming stimulates root and surface SOC respiration with a negative 13C signature that opposes the more positive 13C signal from increased deep SOC respiration. In Deep‐Wet conditions, Recoδ13C suggests reduced deep SOC loss but could also reflect altered diffusion or methane (CH4) dynamics. Together, these results demonstrate that frequent Recoδ13C measurements can detect deep SOC loss and that plants confound the signal. In future studies, soil profile δ13C measurements, vegetation removal across thaw gradients, and isotopic effects of CH4dynamics could further deconvolute deep SOC loss via surface Reco. Carbon (C) stored in permafrost soil is like a global savings account that keeps C out of the atmosphere. Arctic warming makes permafrost soil C vulnerable to microbial decomposition, and C released to the atmosphere would accelerate global warming. In this study we used 13C isotopes, which function like molecular fingerprints, to detect permafrost soil C decomposition from a soil warming experiment that doubled the thawed soil volume and changed soil moisture conditions. We found that permafrost soil C decomposition was best detected when vegetation was removed. Deeper thaw depth had only a small effect on isotopic signatures possibly because the signal from higher permafrost soil C decomposition was overwhelmed by a simultaneous increase in surface soil decomposition and respiration from plants. In wet areas, the isotopic signal changed which could imply reduced permafrost soil C decomposition. In wet areas, methane cycling might also change the isotope signature. We conclude that seasonal 13C sampling could be useful for detecting permafrost soil C decomposition if combined with measurements that can isolate contributions from surface soil, roots, and methane cycling. Developing methods that make it easier to assess permafrost soil C decomposition is critical for estimating the balance of our global C savings account. Vegetation removal shows deep soil C loss does increase with thaw, and plant contributions to Reco dilute delta13C signals from deep soilSeasonal Reco delta13C suggests warming and permafrost thaw may stimulate deep soil respiration and also surface soil and plant respirationWet conditions may reduce deep soil C loss, with possible effects of altered diffusion dynamics and increased methane cycling on delta13C

Chromosomal rearrangements such as inversions can play a crucial role in maintaining polymorphism underlying complex traits and contribute to the process of speciation. In Atlantic cod (Gadus morhua), inversions of several megabases have been identified that dominate genomic differentiation between migratory and nonmigratory ecotypes in the Northeast Atlantic. Here, we show that the same genomic regions display elevated divergence and contribute to ecotype divergence in the Northwest Atlantic as well. The occurrence of these inversions on both sides of the Atlantic Ocean reveals a common evolutionary origin, predating the >100 000-year-old trans-Atlantic separation of Atlantic cod. The long-term persistence of these inversions indicates that they are maintained by selection, possibly facilitated by coevolution of genes underlying complex traits. Our data suggest that migratory behaviour is derived from more stationary, ancestral ecotypes. Overall, we identify several large genomic regions—each containing hundreds of genes—likely involved in the maintenance of genomic divergence in Atlantic cod on both sides of the Atlantic Ocean.

We obtained far-ultraviolet spectra of the Seyfert 1 galaxy NGC 7469 using the Far Ultraviolet Spectroscopic Exploreron 1999 December 6. Our spectra cover the wavelength range 990–1187 Å with a resolution of ~0.05 Å. We see broad emission lines of C?iii, N?iii, O vi, and He iias well as intrinsic absorption lines in the O vi$\lambda\lambda1032,1038$resonance doublet. The absorption arises in two distinct kinematic components at systemic velocities of -569 km?s-1and -1898 km?s-1. Both components are very highly ionized – no significant Lyßabsorption is present. The higher blueshift component is not quite saturated, and it has a total O vicolumn density of $8 \times 10^{14}~\rm cm^{-2}$. It covers more than 90% of the continuum and broad-line emission. The lower blueshift component is heavily saturated and covers only ~50% of the continuum and broad-line emission. It too has a column density of $8 \times 10^{14}~\rm cm^{-2}$, but this is less certain due to the high saturation. We set an upper limit of < $1.5 \times 10^{18}~\rm cm^{-2}$on the O vicolumn density of this component. Its line depth is consistent with coverage of only the continuum, and thus this component may lie interior to the broad emission-line gas. The component at -569 km?s-1has a velocity comparable to the high-ionization X-ray absorption lines seen in the XMM-Newtongrating spectrum of NGC 7469, and photoionization models show that the observed column densities of O viand H iare compatible with their formation in the same gas as that causing the X-ray absorption. The gas at -1898 km?s-1has lower ionization and column density, and no significant X-ray absorption is associated with it.

Multivariate classifiers (such as Linear Discriminant Analysis, Support Vector Machines etc) are known to be useful tools for making diagnostic decisions based on spectroscopic data. However, robust techniques for assessing their performance (e.g. by sensitivity and specificity) are vital if the application of these methods is to be successful in the clinic. In this work the application of repeated cross-validation for estimating confidence intervals for sensitivity and specificity of multivariate classifiers is presented. Furthermore, permutation testing is presented as a suitable technique for estimating the probability of obtaining the observed sensitivity and specificity by chance. Both approaches are demonstrated through their application to a Raman spectroscopic model of gastrointestinal cancer.

Raman spectroscopy is an inelastic scattering technique capable of probing the biochemical changes associated with neoplastic progression in oesophageal tissue. Custom-built fibre-optic Raman probes could potentially provide opportunities for in vivo endoscopic diagnosis of pre-cancerous oesophageal lesions and targeted early therapy. However, prior to commencing a clinical trial convincing ex vivo work must demonstrate multi-operator, multi-centre and multi-system reliability. We report spectral consistency between two operators who independently evaluated two optically identical probes ex vivo. In addition, we demonstrate compatibility with high-definition white light endoscopes and narrow band imaging systems highlighting the potential for future endoscopic multi-modality imaging in the oesophagus.

We describe calibration data and discuss performance of the photon-counting flight detectors for the Ultraviolet Imaging Telescopes on the Astrosat observatory. This article describes dark current, flat-field, and light-spot images for FUV, NUV, and visible band detectors at more than one wavelength setting for each. We also report on nominal-gain and low-gain operations, full- and subwindow read rates, and non-photon-counting modes of operation, all expected to be used in flight. We derive corrections to the event centroids from the CMOS readout arrays, for different centroid algorithms. We derive spatial resolution values for each detector and plots of point-source signal saturation for different flux levels. We also discuss ways to correct for saturation in extended object images.

We discuss selection of QSO candidates from the combined SDSS and GALEXcatalogs. We discuss properties of QSOs within the combined sample and note uncertainties in number counts and completeness, compared with other SDSS-based samples. We discuss color and other properties with redshift within the sample and the spectral energy distributions for subsets. We estimate the numbers of faint QSOs that are classified as extended objects in the SDSS imaging and consequent uncertainties that follow.

We report on photon-counting data taken with a laboratory prototype detector for the ASTROSAT UV imaging telescope, and the selection of the centroiding algorithms and parameter settings for flight. Thresholds are discussed for event recognition. The optimum event centroid algorithm is a 5 × 5 pixel weighted mean, after bias removal accurate to 2%-3%. This can be achieved within each readout frame by using the lowest value corner pixel of the photon event subarray. We also discuss other corner pixel thresholds for flagging double-photon events, and methods of correcting centroiding errors with different algorithms and event rates.

We derive an empirical conversion of SDSS point sources to Jmagnitudes, in addition to resulting estimates of guide stars available to JWST. We also discuss high Galactic latitude fields in the SDSS in terms of completeness limits and populations of stars, galaxies, and QSOs.

This paper presents J-band imaging of two quasars with redshifts of 5.02 and 5.17, respectively, using the Gemini North (GN) telescope. The quasars differ in brightness by several magnitudes. The image resolution ranged from 0.?4 to 1.?0. Both of the quasi-stellar objects (QSOs) have resolved structure in their innermost arcsecond, and the brighter one shows resolved luminosity to a radius of 6?. We also report on GN I- and z-band imaging of two QSOs at a redshift above 6 that are unresolved. The host galaxy luminosities and structure (and upper limits) are discussed and compared with K-band resolved QSOs at z = 4.7 and the general K-zrelationship.

We report data from the commissioning run of the Altair adaptive optics instrument on Gemini North. The bright QSO 3C 273 was observed at f/32 in the Hand Jbands, and at f/14 with Jband, using the QSO itself as guide star. Resolution of approximately 60 mas full width at half-maximum (FWHM) was achieved in Hband. The data and point-spread function are compared with those from the Hubble Space Telescope(HST). The Altair data allow a measurement of the spheroidal inner host galaxy to radii down to about 40 mas. A bright knot seen in visible wavelengths with the Advanced Camera for Surveys (ACS) instrument on HSTis seen in the Jbut not the Hband, and the dust lane seen with ACS is less visible, as expected. Other morphological features, and the jet, are discussed.

We discuss near-infrared star counts at the Galactic pole with a view to guiding the Next Generation Space Telescopeand ground-based near-infrared cameras. Star counts from deep K-band images from the Canada-France-Hawaii Telescope are presented and compared with results from the 2MASS survey and some galaxy models. With appropriate corrections for detector artifacts and galaxies, the data agree with the models down to K? 18 but indicate a larger population of fainter red stars. There is also a significant population of compact galaxies that extend to the observational faint limit of K= 20.5. Recent galaxy models agree well down to K? 19 but diverge at fainter magnitudes.

We have derived far-ultraviolet extinction curves for stars in the Galaxy, LMC, and SMC from spectra of pairs of stars observed with the Far Ultraviolet Spectroscopic Explorer(FUSE) satellite, matched in spectral type and with different amounts of reddening. The stars were observed for other FUSEprograms and were not selected for large reddening. Thus, uncertainties in the derived extinction curves depend on the photometric data. In the case of strongly reddened stars from the Galaxy, the strong H2absorption at the shortest wavelengths is an additional complication. These initial results indicate that there is a family of extinction curves that rise strongly to the Lyman limit and extend the related extinction curves from longer wavelengths.

Direct imaging of the ? Cnc system has resolved the fourth star in the system, which is in orbit around ? Cnc C. The presence of the fourth star has been inferred for many years from irregularities in the motion of star C and recently from C's spectroscopic orbit. However, its mass is close to that of C, making its nondetection puzzling. Observing at wavelengths of 1.2, 1.7, and 2.2 ?m with the adaptive optics system of the Canada-France-Hawaii Telescope, we have obtained images which very clearly reveal star D and show it to have the color of an M2 star. Its brightness is consonant with its being twoM stars, which are not resolved in our observations but are likely to be in a short-period orbit, thereby accounting for the large mass and the difficulty of detection at optical wavelengths, where the magnitude difference is much larger. The positions and colors of all four stars in the system are reported and are consistent with the most recent astrometric observations.

We have obtained new Hubble Space Telescopeobservations of M84, a nearby massive elliptical galaxy whose nucleus contains a ?1.5 × 109M?dark compact object, which presumably is a supermassive black hole. Our Space Telescope Imaging Spectrograph spectrum provides the first clear detection of emission lines in the blue (e.g., [O II] ?3727, H?, and [O III] ??4959, 5007), which arise from a compact region ?028 across centered on the nucleus. Our Near-Infrared Camera and Multiobject Spectrometer images exhibit the best view through the prominent dust lanes evident at optical wavelengths and provide a more accurate correction for the internal extinction. The relative fluxes of the emission lines we have detected in the blue together with those recently detected in the wavelength range 6295-6867 Å by Bower et al. indicate that the gas at the nucleus is photoionized by a nonstellar process instead of hot stars. Stellar absorption features from cool stars at the nucleus are very weak. We update the spectral energy distribution of the nuclear point source and find that although it is roughly flat in most bands, the optical-to-UV continuum is very red, similar to the spectral energy distribution of BL Lac. Thus, the nuclear point source seen in high-resolution optical images by Bower et al. is not a star cluster but is instead a nonstellar source. Assuming isotropic emission from this source, we estimate that the ratio of bolometric luminosity to Eddington luminosity is ~5 × 10-7. However, this could be underestimated if this source is a misaligned BL Lac object, which is a possibility suggested by the spectral energy distribution and the evidence of optical variability we describe.

We present F336W (U), F439W (B), F555W (V), and F675W (R) Wide Field Planetary Camera 2 (WFPC2) photometry of two outer regions of the Local Group dwarf irregular galaxy NGC 6822. The northeast region is ?13'from the galaxy center, whereas the west region lies 10'out and within the wispy low surface brightness outer regions of the galaxy. The fields are not crowded and contain few NGC 6822 stars. We discuss the errors and uncertainties and find that the west region contains a main sequence that extends to stars of about 2 M?, with an age of about 200 Myr. The northeast region has no main sequence or stars younger than 1 Gyr but does contain some luminous red stars that are not matched in the west field. These stars are not clumped in the field. The results suggest that the west region may be a trace of a tidal event that triggered the current star formation in this isolated galaxy.

The understanding of high-energy astrophysical sources often depends on observations over the entire electromagnetic spectrum. Yet, extensive multifrequency observing campaigns can consume the resources of a large number of telescopes, including ground-based and satellite facilities, and usually involve large, unwieldy consortia of observers. Because most X-ray sources are variable on a short time-scale, there is an additional need to make the multifrequency observations simultaneous. The logistical difficulties involved in coordinating these observations, coupled with the vagaries of the weather at ground-based observing sites, mean that comparatively few such coordinated campaigns are attempted; of those that have been tried the success rate for achieving simultaneity is low.

Mature male parr successfully fertilized eggs of anadromous female Atlantic salmon, Salmo salar, in competition with anadromous males under simulated natural conditions. Mating situations were created in which mature male parr and anadromous males competing for the opportunity to spawn with an anadromous female differed in allelic forms of the same enzyme. Females deposited eggs into a sequence of 3 or 4 eggs nests. The mean proportion of eggs in a redd fertilized by parr increased with increasing numbers of parr present at a redd, reaching 23% at male parr: anadromous male ratios of 20:1. Single male parr fertilized, on average, 5% of the eggs in a redd. The proportion of eggs in an egg nest fertilized by parr also depended upon the order of egg nest construction, such that parr mating success was highest at the initial nest constructed and lowest at the final nest. Parr have relatively high fertilization success for their size when compared with the smaller maturation phenotype of other salmonids.

During the commissioning phase of IUE observations were made of a selection of hot stars: the white dwarf HZ43, the hot subdwarf BD + 75°325, the nucleus of the planetary nebula NGC6826, the dwarf nova SS Cygni, and the peculiar object η Carinae. The observations were made in the low dispersion mode and the data have been reduced using a preliminary calibration. The results are presented and discussed for each object.

The lunar barometric tide has been determined with reasonable accuracy, on an annual and seasonal basis, at five stations on the mainland of New Zealand and at three of the outlying islands. The determinations show that in the New Zealand region the lunar tide has a larger amplitude and smaller phase than might have been expected from previously available southern-hemisphere results. In general, the seasonal variation of phase in the New Zealand region conforms to the currently recognised global pattern, with the J-season phase greater than that of the D-season. Similarly, the amplitude variation tends to support the suggestion that, south of latitude 30°S, the D-season amplitude is greater than that of the J-season. Approximate tests are introduced and used to assess the statistical significance of some of the apparent differences in amplitude and phase made evident by the analysis. These assessments indicate that although many of the apparent differences may be attributed to sampling fluctuations, the main regional anomalies in amplitude and phase are likely to be real. It is suggested that these anomalies may indicate a significant regional input of tidal energy to the atmosphere (at the lower boundary) from the Pacific oceanic tide.

Lunar and solar atmospheric tidal oscillations have been determined with reasonable accuracy from a ten-year record of hourly mercury-barometer readings, corrected to mean-sea-level, at Rarotonga (Cook Islands), 21.2°S. For the lunar semidiurnal tide, the annual determination shows an amplitude (56 µb) slightly lower and a phase (51°) much smaller than the values (58 µb, 72°) that would be derived, for the position of Rarotonga, from the spherical harmonic analysis given byHaurwitz andCowley (1969). The seasonal variation of this oscillation, as given by the monthly and J, E, D values, shows most of the characteristic features found in world-wide determinations. In particular, the near equality of the J, D amplitudes at Rarotonga tends to support theHaurwitz andCowley (1969) suggestion of negative J-D values in southern middle latitudes. For the solar tides, the semidiurnal and terdiurnal oscillations at Rarotonga are similar to those found at other stations in the south-west Pacific region. However, for the diurnal oscillation, the annual amplitude (232 µb) is only about half the value (~465 µb) indicated for the position of Rarotonga by the world maps of theS1(p) annual harmonic coefficients given byHaurwitz (1965). It thus seems likely that the relatively small area of lowS1(p) annual amplitude in the eastern part of the south Pacific, as indicated by these maps, is much more extensive than formerly supposed.

Lunar and solar atmospheric tidal oscillations have been determined with satisfactory accuracy from 17 years 11 months of mean sea-level barometric pressure observations taken at Nandi, Fiji. In many respects, the results are consistent with previous tidal determinations in the south-west Pacific region, although these are few and widely scattered. However, the mean annual amplitude of the lunar tide at Nandi, as determined in this study, ~88 µb, is much greater than might have been expected from currently available global amplitude maps. Nevertheless, the probable correctness of this result has been confirmed by the analysis of nearly 6 years of similar data from Nausori (~130 km E.S.E. of Nandi), which yielded a mean annual lunar amplitude of ~88 µb, compared with a Nandi amplitude of ~83 µb for a closely corresponding period.

The review is a discussion of observationally deduced values of the masses, mass-loss rates, temperatures, luminosities and element abundances for the most massive stars. The comparison of these quantities with theoretical calculations is also discussed, in terms of our present understanding of their evolution.

We present I-band images of 3 QSOs of redshift 2 with 0.6 arcsec resolution. The objects are all radio-loud, with compact cores in two cases. Optical luminosities are all high. One QSO is more extended than a point source and two have faint luminous tails. These results are discussed and compared with those for high-redshift QSOs and radio galaxies with large radio lobes.

We present 0.5 arcsec resolution optical images of the low redshift bright broad absorption line (BAL) QSO 1700+518. We find a bright arc 2 arcsec to the NE of the nucleus which is redder than the surrounding host galaxy. There is also a faint radial structure to the SE, which is aligned with the core radio structure. The principal radio structure is slightly resolved component coincident with the optical nucleus and an unresolved lobe 1 arcsec to the W which has no corresponding optical structure. We discuss the morphological and other properties of the QSO.

We present optical imaging of QSO 2305+187 with resolution ranging from 0.1 to 1.0 arcsec, in continuum and line emission. The data are from FOCAM and the HR Cam of the Canada-France-Hawaii telescope, and the Wide Field Camera of the Hubble Space Telescope. These are compared with previously published optical and radio images. The QSO host galaxy has the basic properties of an elliptical, but has significant irregularities, and tidal tails which indicate an ongoing gravitational interaction with a close companion.

the High-Resolution Camera of the Canada-France-Hawaii telescope. We discuss the structure and colors of the jet and details of the host galaxy, which have not been seen in previous observations.

catalog and the Dixon radio source catalog. We find 2010 position coincidences within about 60 arcsec, of which 23 are not noted as radio quasars in Hewitt-Burbidge. We examine the accuracy of the radio source positions of various catalogs and discuss the previously unidentified radio sources. We note an absence of radio quasars of low luminosity at redshifts greater than ~ 2.5.

The Space Telescope Imaging Spectrograph (STIS) instrument was installed on the Hubble Space Telescope(HST) during the second servicing mission, in 1997 February. Four bands cover the wavelength range of 115-1000 nm, with spectral resolving powers between 26 and 200,000. Camera modes are used for target acquisition and deep imaging. Correction for HST's spherical aberration and astigmatism is included. The 115-170 nm range is covered by a CsI MAMA (Multianode Microchannel Array) detector and the 165-310 nm range by a Cs2Te MAMA, each with a format of 2048 × 2048 pixels, while the 305-555 and 550-1000 nm ranges are covered by a single CCD with a format of 1024 × 1024 pixels. The multiplexing advantage of using these two-dimensional detectors compared with the 1 × 512 pixel detectors of the first-generation spectrographs is 1 or 2 orders of magnitude, depending on the mode used. The relationship between the scientific goals and the instrument specifications and design is discussed.

The Adaptive Optics Bonnette (AOB) of the Canada-France-Hawaii Telescope (CFHT) was used to obtain H-band and I-band images of the low-luminosity, optically selected quasar 1055.3+019 at z = 1.06. The FWHMs of stars were 0.?11 in Hand 0.?3 in Iduring these observations, and the detectors used had 0.?034 pixels in Hand 0.?12 pixels in I. Procedures for determining the point-spread function are described. The QSO is clearly resolved in both wave bands, with significant extended flux within 0.?1 of the nucleus. Overall, it appears to be elongated in the direction of a knot and connecting feature extending about 1?northeast of the nucleus visible in the H-band image. There are no other evident close companions, but the host galaxy's hybrid luminosity profile and off-centered nucleus indicate recent tidal disturbance. The I - H colors of the host galaxy correspond to an unreddened stellar population that is currently star forming or is within a very short time of ending an initial starburst. The reddening must be small to match any models.

We present 20 cm and 6 cm maps of 38 QSOs observed in the B configuration of the VLA. The maps are snapshots used in the discussion of the effects of cluster environment on radio properties of QSOs by Hutchings et al. We display maps of all QSOs from the sample of 43 that have significant structure.

We review changes to the characteristics of the Goddard High Resolution Spectrograph (GHRS) which resulted from the installation of the Corrective Optics Space Telescope Axial Replacement (COSTAR) on the Hubble Space Telescope. The introduction of two new optical elements into the light path altered the spectral distribution of the light, decreasing the amount of light striking the instrument by about 30% at wavelengths greater than 1200 Å and effectively eliminated all radiation at wavelengths less than 1130 Å. However, at the longer wavelengths the improved focus offset this loss when the Large Science Aperture (LSA) was used and increased the overall throughput of the Small Science Aperture (SSA) by a factor of 2. The improved focus also enhanced the spectral resolution of LSA observations and improved the ability of the instrument to observe in crowded fields.

H-alpha observations obtained during the 1977 coordinated campaign on Cyg X-1 are presented. Photographic and reticon data were corrected for the primary-star photospheric absorption-line profile and combined in five phase bins to increase the signal-to-noise ratio. The remaining emission profile differs from that observed in 1974, showing a broad, double-peaked structure at all phases, with a central absorption feature which changes systematically with phase. The emission appears to be associated largely, but not entirely, with the optical primary and is very similar to the H-alpha emission in the similar binary HD 152667 = V861 Sco.

Rotationally broadened line widths are measured from lambda spectrum scans of 26 O and B stars. Similar quantities are measured in the visual spectral region for about half of them. The ratio of these line widths, and values for V crit and V sin i are derived and used to estimate omega and i for 24 stars. The applicability of the simple theory of Hutchings (1976) is discussed and the distributions of omega and i for the whole samples of B and Be stars from this and previous investigations are examined and discussed. Of particular interest is the indication that Be stars do not rotate at V crit' and have a random distribution of rotational axes.

Spectroscopic data are examined on the faint reddened Of star HDE 313846. The spectrum shows strong emission in all N III lines, and emission in C III, He II, Si IV, He I, and H as well as the usual Of emissions. Weaker emission, probably due to Fe II and Ni II forbidden lines is seen in the red region of the spectrum. All absorption lines indicate mass outflow at medium to high velocity. The star is compared with other extreme Of stars and its physical parameters are discussed.

Line identifications, velocities, and line strengths are presented for four luminous composite systems in the LMC: R67, R84, R94, and R108. Estimates of the luminosities of the cool companions suggest they are similar to other supergiants in both the LMC and the Galaxy. From measurements of the ratio of blue to red stars with wavelength it is inferred that the blue components are several magnitudes brighter (and possibly more massive) than their nearest counterparts (the VV Cephei stars) in the Galaxy. Other spectroscopic evidence shows that three of these systems also have a higher excitation, more extensive emission regions, or both, than the VV Cep stars.

Spectroscopic data are presented for the cataclysmic variable 0623 + 71. The spectrum contains only narrow, weak Balmer emission, and very weak emission lines of HeI, HeII, and CII. The period of this system is not uniquely established by the data. The most probable periods are 0.1390 and 0.1535 day. Based on the former period, other elements are determined to be: V0= -81 + or - 3 km/s, K = 71 + or - 5 km/s, T0= 2446073.836 + or - 0.002; while on the latter, V0= -77 + or - 4 km/s, K = 72 + or - 5 km/s, T0= 2446073.834 + or 0.002. A circular orbit is adopted for both sets of solutions. The masses of the white dwarf and the lower luminosity star are discussed.

Results of single-trailed spectrograms of the magnetic accreting white-dwarf binary 0139 - 68 are presented. The spectral resolution is approximately 2.5 A and the time resolution is 45 seconds. Line-profile changes and radial velocities are derived and described. A discussion of possible orbital velocities indicates probable masses of 0.2-0.6 solar mass for the white-dwarf primary and 0.3 solar mass for the M-star secondary. The position of the active pole is suggested. The origin of the high-velocity line components is not clear, but their behavior is similar to those in the system VV Pup.

Spectroscopic data are presented from the optical primary of the LMC X-ray source 0535 - 668 during its optical low state. From these data the star appears as a normal B1 star, slightly evolved off the main sequence. Adopting the X-ray outburst period of 16.65 days, radial velocities indicate an orbit with a high eccentricity, and periastron passage very close to the X-ray flux peak. Probable masses are normal for the primary and the pulsar. At periastron, the center of mass separation is less than the primary-star diameter, and during optical outburst the photosphere is larger than the minimum separation. Orbital parameters and implied quantities are discussed.

Far-ultraviolet spectra have been obtained of the eclipsing, hot subdwarf binary, BE UMa, with phase coverage in the 2.3-day orbital period concentrated near minimum light. No clearly phase-related spectral changes were found, but the UV continuum appeared to be in a highly variable state, with changes of a factor of two occurring on a time scale of hours. The hot star in this system may be one of the few known PG 1159-035 variables, which show nonradial pulsations. If so, this is the first such star known in a binary system and thus should be important for determining the physical properties of these stars.

Measurements of BR 52 (= FDA 47, = HV 5947) over three years show it to have a constant high radial velocity (within the measuring errors), in spite of the expectation (from the initial observations and its known photometric variations) that it might be a spectroscopic binary of large radial-velocity amplitude. Hydrogen absorption-line components, which have been thought to be due to a hot companion, appear rather to be formed in a variable stellar wind from the WR star. The high velocity (about +470 km/s) of BR 52 with respect to the LMC (about +270 km/s) is noted. A new WN5 star, designated W0536-67, has been found near the X-ray source CAL 60, although it does not appear to be the optical identification for this source. Some details about its spectrum and velocity are given.

The authors present spectroscopic data on the O6 + WN3 binary R31 in the SMC, which improve the orbital determination of Moffat (1982). The period is found to be 6.538 days. From several considerations they consider an eccentricity of ?0.2 to be possible. From the absence of known eclipses and lack of evidence that the primary fills its Roche lobe, they infer that the orbital inclination is ?60° or less. The stellar masses are most probably 65 Msun; and 12 Msun;. This makes the O star one of the most massive yet measured. Velocity differences between absorption lines of different ions are thought to be due to stellar wind effects, and may be phase dependent. The unusually large mass ratio is discussed.

Spectroscopic data are presented for the cataclysmic variable VY Scl taken during the rise from the low state of 1983 when the spectrum still showed strong emission lines. The period is not definitely established but is probably 0.1662 days. No strong phase-related spectral changes are seen, but there are night-to-night changes in the line intensities. The system appears to be viewed at a low inclination, with a white dwarf mass of 0.8 solar mass or more. The emission-line profiles have a narrow peak whose velocity variation is small but in phase with the broad-line base.