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Speckle Interferometry at the US Naval Observatory. V.
The results of 1544 speckle interferometric observations of 637 binarystars, ranging in separation from 0.25" to 5.25", are tabulated. Theseobservations were obtained using the 66 cm refractor at the US NavalObservatory in Washington, DC, with an intensified CCD detector. This isthe fifth in a series of papers presenting measures obtained with thissystem and covers the period 1998 January 1 through December 31. Randomerrors for all measures are estimated to be 17.6 mas in separation and0.55d/ρ in position angle, where ρ is the separation inarcseconds.
| Speckle Interferometry at the US Naval Observatory. IV.
The results of 1314 speckle interferometric observations of 625 binarystars, ranging in separation from 0.2" to 5.2" with a limiting secondarymagnitude of V=11, are tabulated. These observations were obtained usingthe 66 cm refractor at the US Naval Observatory in Washington, DC, withan intensified CCD detector. This is the fourth in a series of paperspresenting measures obtained with this equipment and covers the period1997 January 1 through December 31. Random errors for all measures areestimated to be 18 mas in separation and 0.57d/rho in position angle,where rho is the separation in arcseconds.
| A preliminary compilation of DS-programme star positions
A catalog is presented of the double-star-program (DS-program) starpositions, listing right ascensions for 930 DSs and declinations for1225 DSs of the program. The positions were compiled from the observedvalues obtained between 1980 and 1987 with the meridian circles of sixUSSR observatories (the Moscow, Kazan', Kiev, Khar'kov, Odessa, andTashkent Observatories) and the Belgrade Observatory. The measurementsand the treatment of the observational material were performed using therelative method, and the FK-4 system stars were used as reference stars.
| Micrometer Measurements of Visual Double Stars - Part Three -
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| On the distribution of interstellar matter around the sun
Available data on interstellar line or EUV continuum absorptionattributable to the local (r equal to or less than 100 pc) interstellarmedium are presented and analyzed as a whole for clues leading to adeeper understanding of the spatial distribution and physical propertiesof this material. By using these data in conjunction with upper limitsprovided by polarization and color excess surveys and relatingeverything to the neutral-hydrogen column density, it is shown that thedata are consistent with a simple model that assumes the relativelypervasive presence of a tenuous (nH = 0.07 per cu cm), possibly warm (T= 1,000-10,000 K) gas extending uniformly out to considerable distancesfrom the sun in most directions. The only region manifestly clear ofthis material lies in the 200 deg to 270 deg galactic longitude range inboth high and low latitudes. Strong density discontinuities are clearlyobservable at r approximately 100-150 pc in the general directions ofthe Sco-Cen and Per associations and a weaker discontinuity much closerto the sun running along a ridge oriented parallel to the lineconnecting their centers. Beyond these fronts, the space density ofinterstellar matter must fall to very low values that extend out toseveral hundred parsecs or so from the sun. These results are notincompatible with H I, 21-cm, and soft X-ray all-sky surveys. Theimplication of these findings for the theory of the interstellar mediumand EUV visibility is briefly discussed.
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