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At least 19 records

On the linearity of the SWP camera of the international ultraviolet explorer /IUE/ - A correction algorithm

An algorithm is presented for correcting IUE low resolution spectral images obtained with the SWP camera for some of the non-linearity effects reported by Bohlin et al. (1980). The non-linearity problem, which affects SWP images processed at Goddard Space Flight Center in the period May 22, 1978 to July 7, 1979 and at VILSPA in the period June 14, 1978 to August 6, 1979, was essentially due to the use of an Intensity Transfer Function (ITF) that erroneously included a blank image in the 20 percent exposure level. The correction algorithm described here was adopted by the three IUE Agencies in November 1979 as being suitable for most IUE users. It has the advantages to be applicable to any kind of low resolution SWP spectra, to introduce errors which are usually less than the intrinsic photometric errors, and to be of simple application. The results obtained by applying the method to a representative set of spectra of both point and extended sources are reported. In addition, a new evaluation of linearity and reproducibility of the SWP spectral data is provided, based on the improved ITF.

Holm, A.

The cool-star spectral catalog: A uniform collection of IUE SWP-LOs

Over the past decade and a half of its operations, the International Ultraviolet Explorer has recorded low-dispersion spectrograms in the 1150-2000 A interval of more than 800 stars of late spectral type (F-M). The sub-2000 A region contains a number of emission lines that are key diagnostics of physical conditions in the high-excitation chromospheres and subcoronal 'transition zones' of such stars. Many of the sources have been observed a number of times, and the available collection of SWP-LO exposures in the IUE Archives exceeds 4,000. With support from the Astrophysics Data Program, we have assembled the archival material into a catalog of IUE far-UV fluxes of late-type stars. In order to ensure uniform processing of the spectra, we: (1) photometrically corrected the raw vidicon images with a custom version of the 1985 SWP ITF; (2) identified and eliminated, sharp cosmic-ray 'hits' by means of a spatial filter; (3) extracted the spectral traces with the 'optimal' (weighted-slit) strategy; and (4) calibrated them against a well-characterized reference source, the DA white dwarf G191-B2B. Our approach is similar to that adopted by the IUE Project for its 'Final Archive', but our implementation is specialized to the case of chromospheric emission-line sources. We measured the resulting SWP-LO spectra using a semi-autonomous algorithm that establishes a smooth continuum by numerical filtering, and then fits the significant emissions (or absorptions) by means of a constrained Bevington-type multiple-Gaussian procedure. The algorithm assigns errors to the fitted fluxes - or upper limits in the absence of a significant detection - according to a model based on careful measurements of the noise properties of the IUE's intensified SEC cameras. Here, we describe the 'visualization' strategies we adopted to ensure human-review of the semi-autonomous processing and measuring algorithms; the derivation of the noise model and the assignment of errors; and the structure of the final catalog as delivered to the Astrophysics Data System.

Ayres, T.

Spectral anomalies in low dispersion SWP images

Physical interpretation of IUE spectra obtained with the SWP camera may be significantly affected by artificial spectral features of several types. In low dispersion large aperture SWP exposures of sources with nominally featureless spectra, a spectral imprint which alters the shape of the continuum, several spurious "emission features" which recur at fixed locations on the camera target, and fixed pattern noise which can result in illusory emission and absorption features were identified. The anomalies appear in spectra extracted from line by line files generated by IUESIPS at all epochs, regardless of the ITF or rectification scheme used for processing.

Hackney, R. L.

Signal-to-noise ratios in IUE SWP-LO spectra of chromospheric emission-line sources

The short-wavelength-prime (SWP) detector of the International Ultraviolet Explorer should operate near the photon-counting limit, but the noise levels in flat-field images are several times higher. The exaggerated noise can be traced to the incomplete removal of the pixel-to-pixel granularity of the television frames by the prevailing spectral image processing system. An empirical noise model for the current-epoch photometric linearization strategy and one for a hypothetical processing system that achieves complete flat fielding of the raw images are derived. A formula is then proposed to predict the signal-to-noise ratio in the measured flux of an emission line (possibly superimposed on a smooth continuum) in an IUE low-dispersion (5 A resolution) far-ultraviolet (1150 A-1950 A) spectrum as recorded with the SWP camera. For illustration, the formula is specialized to the important C IV 1549 A feature of F-K stars. The S/N relation permits one to determine sensitivity limits, upper limits in faint exposures, and optimum exposure times.

Ayres, Thomas R.

A line identification study of the IUE SWP high dispersion spectrum of the UV-bright star Barnard 29 of Messier 13

A line identification study was performed of the coaddition of three SWP high dispersion IUE exposures of the UV-bright star Barnard 29 of Messier 13. One of these images took two IUE shifts. The previous study by de Boer and Savage (1983) was extended and stellar lines of C I, C II, C III, C IV, N I, N III, O I, O III, O IV,Al III, Si II, Si III, Si IV, P III, S II, and S III and interstellar lines of C I, C II, C IV, N I, N III, N IV, N V, O I, Al II, Al III, Si II, Si IV, S II, and Fe II were found. These lines are the strongest expected lines in a hot Population II star. Apparent intensity minima corresponding to interstellar features are noted, especially those matching a high velocity cloud found by de Boer and Savage.

Adelman, S. J.

A far-ultraviolet atlas of symbiotic stars observed with IUE. 1. The SWP range

This atlas contains sample spectra from the far-ultraviolet observations of 32 symbiotic stars obtained with the International Ultraviolet Explorer (IUE) satellite. In all, 394 low-resolution spectra from the short-wavelength primary (SWP) camera covering the range 1200-2000 A have been extracted from the IUE archive, calibrated, and measured. Absolute line fluxes and wavelengths for the prominent emission lines have been tabulated. Tables of both the general properties of these symbiotics and of features specific to the spectrum of each are included. The spectra shown are representative of the different classes of symbiotic stars that are currently in the IUE archive. These include known eclipsing systems and those that have been observed in outburst (as well as quiescence).

Meier, S. R.

A reanalysis of the SWP-HI IUE observations of Capella

We have reanalyzed the numerous high-resolution, far-ultraviolet observations of Capella made by the International Ultraviolet Explorer (IUE) in its 16 yr lifetime. Our purpose was to search for long-term profile variations in Capella's ultraviolet emission lines and to complement the analysis of Goddard High Resolution Spectrograph (GHRS) observations of Capella, discussed in a companion paper (Linsky et al. 1995). We implemented a state-of-the-art photometric correction and spectral extraction procedure to improve S/N and control potential sources for systematic errors. Nevertheless, we were unable to find compelling evidence for any significant long-term profile variations. Previous work has shown that the G8 primary star is only a minor contributor to the high-excitation transition region lines but is a significant contributor to the low-excitation chromospheric lines. We have found exceptions to this rule, however. We find that the G8 star is responsible for a significant portion of Capella's N V lambda lambda 1239, 1243 emission, but is not a large contributor to the S I lambda 1296, Cl I lambda 1352, and O lambda 1356 lines. We suggest possible explanations for these behaviors. We also find evidence that the He II lambda 1640 emission from the G1 star is from the transition region, while the He II lambda 1640 emission from the G8 star is chromospheric, consistent with the findings of Linsky et al. (1994). The C II lambda 1336 line shows a weak central reversal. It is blueshifted by about 9 km/s with respect to the centroid of the emission from the G1 star. While the central reversal of the C II line is blueshifted by about 9 km/s with respect to the centroid of the emission from the G1 star. While the central reversal of the C II line is blueshifted, the central reversal of the Si III lambda 1207 line discussed by Linsky et al. (1994) is not.

Wood, Brian E.

Southwest Regional Partnership on Carbon Sequestration: Phase III (Final Scientific/Technical Report)

The Southwest Regional Partnership on Carbon Sequestration (SWP) is one of 7 regional partnerships formed in 2003 under the U.S. Department of Energy’s (DOE) Regional Carbon Sequestration Partnerships (RCSPs) initiative. The overall purpose of the initiative was to help determine and implement the technology, infrastructure, and regulations most appropriate to promote carbon storage in different regions of the country. Covering Arizona, Colorado, New Mexico, Oklahoma, Utah, and parts of Texas, Wyoming, and Kansas, the SWP evaluated regional carbon storage and utilization potential and focused on technologies and sites that could complement the region’s strong position in energy production. The project progressed through three phases: • Phase I (2003–2005): Characterized regional geologic formations and CO 2 sources, assessed sequestration potential, and identified pilot test sites. • Phase II (2005–2013): Conducted small-scale field tests to validate sequestration methods, including geologic and terrestrial projects. • Phase III (2008–2022): Demonstrated large-scale CO 2 injection at a commercial oil field to test monitoring, verification, and long-term storage strategies. This report covers Phase III. The final project site, the Farnsworth Unit (FWU) in Texas, provided real-world testing of reservoir characterization, monitoring, and risk evaluation tools and processes that could be used in any commercial scale carbon capture, utilization, and storage (CCUS) project. Extensive data collection and analysis helped refine best practices for reservoir characterization, injection monitoring, and storage verification. The SWP contributed to national databases, DOE best practice manuals, and regional geological assessments to support future sequestration efforts. Key lessons learned include the importance of robust data management, strategic site selection, regulatory navigation, and effective industry collaboration. The project’s findings will inform ongoing and future carbon storage initiatives. Task 1 (Regional Characterization) • The SWP continued to participate in national outreach efforts and NATCARB. • The SWP evaluated multiple potential sites before selecting the FWU as the primary field test location. Task 2 (Public Outreach and Education) • The SWP contributed to national databases, DOE best practice manuals, and regional geological assessments to support future sequestration efforts. Task 3 (Permitting and Regulatory Compliance) • The SWP ensured compliance with federal and state regulations, including National Environmental Policy Act (NEPA) requirements. • The SWP obtained all necessary permits for drilling, injection, and monitoring activities. Task 4 (Site Characterization and Planning) • The SWP developed work plans for four key activities: characterization, simulation, monitoring and verification, and risk evaluation. • The SWP collected and synthesized legacy data from multiple sources to build initial static geological models and dynamic reservoir models demonstrating project feasibility. • The SWP conducted an initial risk evaluation and developed mitigation plans. Task 5 (Field Operations and Data Collection) • The SWP drilled, logged, and cored three characterization wells to gather critical subsurface data. • The SWP conducted multiple geophysical surveys, including 3D seismic, crosswell seismic, and vertical seismic profiling, to improve reservoir characterization. Task 6 (Monitoring and Verification) • The SWP performed extensive geological characterization using data from characterization wells and seismic surveys. • The SWP established a surface monitoring network to track CO 2 flux in soil gas, groundwater chemistry, and near-surface atmospheric CO 2 levels. • The SWP built and refined reservoir models to study the effects of relative permeability on simulation behavior and improve calibration with experimental data. Task 7 (Risk Assessment and Model Refinement) • The SWP conducted multiple studies to evaluate reservoir integrity, predict CO 2 plume behavior and improve predictive modeling capabilities. • The SWP refined geological models and used them to enhance the accuracy of simulation models. • The SWP continued quantitative risk assessment of top-ranked risks and strengthened the link between qualitative and quantitative risk methodologies.

02 PETROLEUM

Meteorological and Soil Data from Ecohydrology Sensor Towers at Pump House and Snodgrass Mountain in East River Watershed, Colorado, 2019-2025

This data package includes hourly meteorological and soil sensor data at eight ecohydrology monitoring sites in East River Watershed, Colorado as part of the Watershed Function Scientific Focus Area (WFSFA) research led by Lawrence Berkeley National Lab (LBNL). Four field sites were located on the hillslope of East River (ER) near Pump House (PH) at Mount Crested Butte (ER-PHS1 to 4), and the other four are in the Snodgrass Mountain (SG) area (SG-EHS5 to 8). In terms of vegetation cover, three sites are in montane grasslands (ER-PHS1, ER-PHS2, and SG-EHS5), three are below evergreen conifer canopy (ER-PHS3, SG-EHS6, and SG-EHS7), and two are below deciduous aspen canopy (ER-PHS4 and SG-EHS8). The monitoring period began in October 2019 at the East River sites, in October 2020 at SG-EHS5 and SG-EHS6, and in October 2021 at SG-EHS7 and SG-EHS8. In September 2024, all four East River sites were fully retired. The four Snodgrass Mountain sites remain active. Each site is equipped with a comprehensive suite of meteorological sensors on a tripod and soil sensors that measure weather, energy fluxes, and soil variables. This data package includes measurements from ten different types of sensors and up to thirteen individual sensors per site, including (1) a weather station (measurement height ranges from 2.8~3.8 meters (m) above ground), (2) a quantum sensor for photosynthetic active radiation (PAR) (2.4~3.3m), (3) a net radiometer (1.7~2.1m), (4) an infrared radiometer (1.6~2.2m), (5) a sonic distance sensor (1.5~1.9m), (6) a soil carbon dioxide (CO2) flux chamber (0m), (7) a soil heat flux plate (-0.05m below ground), (8) a soil oxygen sensor (-0.3m), (9) a soil water potential sensor (-0.3m), and (10) soil water content sensors at 3~4 depths (-1.15 ~ -0.1m). A total of twenty-three variables is reported in this data package, including (1) atmospheric variables: air temperature (TA), atmospheric pressure (PA), vapor pressure (VP), and vapor pressure deficit (VPD), (2) precipitation variables: rain precipitation (P) and snow depth (D_SNOW), (3) energy fluxes variables: four-component net radiation (NETRAD) (shortwave/longwave incoming/outgoing radiation, SW_IN, SW_OUT, LW_IN, LW_OUT), photosynthetic photon flux density (PPFD), and soil heat flux (G), (4) soil variables: soil water content (SWC), soil water potential (SWP), soil temperature (TS), soil bulk electrical conductivity (COND_SOIL), and soil gaseous oxygen concentration (O2_SOIL), (5) wind variables: two-dimensional wind speed (WS), gust speed (WS_MAX), and wind direction (WD), and (6) surface variables: surface infrared temperature (T_CANOPY) and soil CO2 flux (CO2_SOIL). Please see the Methods section for data processing and QA/QC steps taken to generate the hourly datasets. The following files are included in this data package (notes on version: v{x}-{y}, where x is the metadata version, and y is the data version, when applicable): (1) “metadata_site_v{x}-{y}.csv” - a site metadata file that summarizes location information of all sites, including site ID, description, coordinates, timeframe, elevation, and vegetation cover, (2) “metadata_instrument_v{x}-{y}.csv” - an instrument metadata file that summarizes sensor information of all sites, including sensor manufacturer and model, measurement height, and sampling and averaging interval of all variables, (3) "data_{SITE_ID}_v{x}-{y}.csv" - eight data files that contain hourly data of each site indicated by {SITE_ID} in the filename, (4) “/figure/data_{SITE_ID}_v{x}-{y}.png" - eight figures that help visualize data of each site indicated by {SITE_ID} in the filename, (5) “/photo/*” - photos of each site indicated by {SITE_ID} in the filename, and (6) four file level metadata (flmd.csv) and data dictionary (*_dd.csv) files that summarize file, header, column, and variable information of all files. Notes: (1) Measurement height: Each variable name is followed by conventional positional qualifiers “H_V_R”, where H indicates the relative horizontal positions of that specific variable, V the vertical positions, and R the replicates. In this data package, only the vertical qualifier V varies, and V increases from the highest vertical position (V=1) to the lowest. Variables with the same qualifier are not necessarily measured by the same sensor, and the same variable with the same qualifier across different sites are not necessarily measured at the same height. Please refer to “metadata_instrument.csv” for the sensor information and measurement heights, and whether a variable is measured below the canopy. (2) Variable availability: Snow depth is not available at ER-PHS3 and SG-EHS7. SWC, soil temperature, and soil bulk EC at the deepest depth (<-1m) are not available at SG-EHS6 and SG-EHS7. The missing value code for numeric variables is -9999, except for SWP. For SWP, the missing value code is +9999, because SWP values are negative. (3) Sampling frequency: Please refer to “metadata_instrument.csv” for the increase of sampling frequency of some variables from 30-min to 1-min at ER-PHS1 to 4 in July 2020. (4) Sensors: While the methods of each sensor are not detailed, all sensors are commercially available, and their methods can be found in their manuals. Please refer to “metadata_instrument.csv” for the sensor manufacturer and model information. This work was supported by the Watershed Function Science Focus Area at Lawrence Berkeley National Laboratory funded by the US Department of Energy, Office of Science, Biological and Environmental Research under Contract No. DE-AC02-05CH11231.

54 ENVIRONMENTAL SCIENCES

Comparison of electric and growth responses to excision in cucumber and pea seedlings. II. Long-distance effects are caused by the release of xylem pressure

Excision of a growing stem causes local wound responses, such as membrane depolarization and growth inhibition, as well as effects at larger distances from the cut. In this study, cucumber hypocotyls were excised 100 mm below the hook, so that the growing region was beyond the reach of the wound-induced depolarization (up to 40 mm). Even at such a distance, the cut still caused a considerable and rapid drop in the hypocotyl growth rate. This growth response is not a direct wound response because it does not result from the cut-induced depolarization and because it can be simulated by root pressure manipulation (using a pressure chamber). The results indicate that the growth response resulted from the rapid release of the xylem pressure upon excision. To test this conclusion we measured the xylem pressure by connecting a pressure probe to the cut surface of the stem. Xylem pressure (Px) was found to be +10 to +40 kPa in cucumber hypocotyls and -5 to -10 kPa or lower in pea epicotyls. Excision of the cucumber hypocotyl base led to a rapid drop in Px to negative values, whereas excision in pea led to a rapid rise in Px to ambient (zero) pressure. These fast and opposite Px changes parallel the excision-induced changes in growth rate (GR): a decrease in cucumber and a rise in pea. The sign of the endogenous xylem pressure also determined whether excision induced a propagating depolarization in the form of a slow wave potential (SWP). Under normal circumstances pea seedlings generated an SWP upon excision whereas cucumber seedlings failed to do so. When the Px in cucumber hypocotyls was experimentally inverted to negative values by incubating the cumber roots in solutions of NaCN or n-ethylmaleimide, excision caused a propagating depolarization (SWP). The experiment shows that only hydraulic signals in the form of positive Px steps are converted into propagating electric SWP signals. These propagating depolarizations might be causally linked to systemic 'wound' responses, which occur independently of the short-distance or direct wound responses.

Non-NASA Center

Faint object studies with IUE

To push IUE to the limit on faint sources, detector background contributions from the night sky, energetic particle events, detector flaws and calibration errors must be established. Multiple spectra of faint nebular filaments were intercompared with multiple spectra of sky background in a study of the Crab Nebula. Radiation hits dominate the background of any long exposure spectrum but bright spots of the detector can be misconstrued to be radiation hits, or spectral information. The spectra were normalized and then, on a pixel by pixel basis, average and median spectra were constructed. Four data sets (six SWP nebular, six SWP sky, six LWR nebular, and six LWR sky) were processed in parallel. A number of bright and faint background features remain, especially for SWP images. Several features could be misconstrued to be emission from a faint object.

Gull, T. R.

Far-ultraviolet radiation from disk globular clusters

IUE spectra obtained in a survey of the metal-rich disk system of globular clusters are presented. Significant FUV fluxes were detected in the 1200-2000-A short-wavelength (SWP) range of the IUE Observatory in several disk globular clusters. These clusters are the most metal-rich known to have an FUV flux. Three clusters show spectral energy distrbutions (SEDs) clearly rising at shorter wavelengths, not unlike the upturns observed in the bulges of metal-rich elliptical galaxies. Several others with weak SWP detections appear to have flat or uncertain spectral energy distributions. Blue stragglers provide a possible explanation for flux redder than 2000 A in clusters showing weaker flux in the SWP region, and with flat or declining SEDs.

Rich, R. M.

Collaborative observations of HDE 332077

IUE low dispersion observations were made of the Tc-deficient peculiar red giant (PRG) star, HDE 332077, to test the hypothesis that Tc--poor PRG's are formed as a result of mass transfer from a binary companion rather than from internal thermal pulsing while on the asymptotic red giant branch. Previous ground-based observations of this star indicated that it is a binary, but the secondary star was too massive for an expected white dwarf. A deep, SWP exposure was needed to search for evidence of an A-type main-sequence companion. We obtained a 120 minute LWP exposure (LWP 23479), followed by a collaborative 120 minute SWP exposure (SWP 45113). These observations were combined with our earlier IUE and optical data on this PRG star to model the spectral energy distribution of the system.

Ake, T.

Collaborative observations of HDE 332077

IUE low dispersion observations were made of the T(sub c)-deficient peculiar red giant (PRG) star, HDE 332077, to test the hypothesis that T(sub c)-poor PRG's are formed as a result of mass transfer from a binary companion rather than from internal thermal pulsing while on the asymptotic red giant branch. Previous ground-based observations of this star indicated that it is a binary, but the secondary star was too massive for an expected white dwarf. A deep, short wavelength prime (SWP) exposure was needed to search for evidence of an A-type main-sequence companion. We obtained a 120 minute LWP exposure (LWP 23479), followed by a collaborative 1230 minute SWP exposure (SWP 45113). These observations were combined with our earlier IUE and optical data on this PRG star to model the spectral energy distribution of the system.

Ake, Thomas B., III

Geologic Traverse Planning for Apollo Missions

The science on Apollo missions was overseen by the Science Working Panel (SWP), but done by multiple PIs. There were two types of science, packages like the Apollo Lunar Surface Experiment Package (ALSEP) and traverse science. Traverses were designed on Earth for the astronauts to execute. These were under direction of the Lunar Surface PI, but the agreed traverse was a cooperation between the PI and SWP. The landing sites were selected by a different designated committee, not the SWP, and were based on science and safety.

Lofgren, Gary

The Global Exploration Roadmap: Opportunities for Lunar Science

The Global Exploration Roadmap (GER) has been developed by the International Space Exploration Coordination Group (ISECG comprised of 14 space agencies) to define various pathways to getting humans beyond low Earth orbit and eventually to Mars. Such pathways include visiting asteroids or the Moon before going on to Mars. This document has been written at a very high level and many details are still to be determined. However, a number of important papers regarding international space exploration can form a basis for this document.This poster will focus on developing the Lunar Vicinity scenario by adding detail via mapping a number of recent reportsdocuments into the GER. The documents highlighted here are in no way meant to be all encompassing and other documents can and should be added, (e.g., the JAXA Space Exploration Roadmap). This exercise is intended to demonstrate that existing documents can be mapped into the GER despite the major differences in granularity, and that this mapping is a way to promote broader national and international buy-in to the Lunar Vicinity scenario.The documents used here are: the Committee on Space Research (COSPAR) Panel on Exploration report on developing a global space exploration program, the Strategic Knowledge Gaps (SKGs) report from the Lunar Exploration Analysis Group (LEAG), the Lunar Exploration Roadmap developed by LEAG, the National Research Council report Scientific Context for the Exploration of the Moon (SCEM), and two journal articles, the scientific rationale for resuming lunar surface exploration, and the astrobiological benefits of human space exploration.In addition, the ISECG is in the process of developing a Science White Paper (SWP) to accompany the next edition of the GER, due in late 2016. The SWP will be an important tool to communicate science which will be able to be accomplished at human exploration destinations to policymakers. This abstract will discuss the process of developing this SWP and ways in which the global science community can become engaged in its development.

Schmidt, Gregory

Upscaling Methods Applied to a Fine-Scale Reservoir Model

This study was conducted as part of the Southwest Regional Partnership on Carbon Sequestration (SWP) project to evaluate how upscaling fine-scale simulation models to coarse-scale simulation models impacted the results. The focus was on the Farnsworth Unit (FWU) and its Morrow' B' Sandstone reservoir, specifically the west half of the field. Due to data limitations and the geologic characteristics of the surrounding area, the upscaling was limited to the west half of the FWU rather than a broader basinscale model. The primary aim was to explore how upscaling impacts numerical simulation models, particularly regarding CO 2 -enhanced oil recovery (EOR) and storage capacity predictions. Upscaling was necessary to reduce computational demands when transitioning from high-resolution geological models to coarser grids, as large-scale simulations with finer grids can be computationally prohibitive. This study expands on previous work by the SWP to understand how additional upscaling, applied to already fine-scale numerical simulation models, affects reservoir performance simulations (Ampomah, Balch, & Grigg, 2015). This is key to understanding how loss of resolution can affect coarsescale model results that may be used for large sensitivity analyses, uncertainty quantifications, and training data for machine learning applications.

02 PETROLEUM

RW Tauri as a weak W Serpentis star

Observations of the short-period eclipsing binary RW Tau made with the LWR and SWP cameras of the IUE satellite and with the ITS scanner at the 3-m Shane telescope of the Lick Observatory in August and October, 1982, are reported and analyzed. At total eclipse, weak excess continuous radiation in the LWR range and emission lines at Si IV (1), C IV (1), Al III (1), Fe III (34), and Mg II (1) in the SWP range were detected. These findings are similar to those for W Ser-type binaries such as U Cep. The parameters of the system are estimated using a bilinearly interpolated atmospheric model of the type developed by Kurucz (1979): primary-star T(eff) = 11,750 K, log g = 4.2, cool-component spectral type = K0 III, E(B-V) color excess = 0.14 mag, system distance = 270 pc. The implications of these findings for proposed models of the W Ser binaries are discussed, and the observation of a possible distant optical companion star 45 arcsec from RW Tau is reported.

Plavec, M. J.