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An Einstein Observatory SAO-based catalog of B-type stars
About 4000 X-ray images obtained with the Einstein Observatory are usedto measure the 0.16-4.0 keV emission from 1545 B-type SAO stars fallingin the about 10 percent of the sky surveyed with the IPC. Seventy-fourdetected X-ray sources with B-type stars are identified, and it isestimated that no more than 15 can be misidentified. Upper limits to theX-ray emission of the remaining stars are presented. In addition tosummarizing the X-ray measurements and giving other relevant opticaldata, the present extensive catalog discusses the reduction process andanalyzes selection effects associated with both SAO catalog completenessand IPC target selection procedures. It is concluded that X-rayemission, at the level of Lx not less than 10 exp 30 ergs/s, is quitecommon in B stars of early spectral types (B0-B3), regardless ofluminosity class, but that emission, at the same level, becomes lesscommon, or nonexistent, in later B-type stars.
| Miscellaneous spectroscopic notes
Results of slit-spectrograph observations are reported for approximately260 stars. The data presented range from recognition of many new Ap, Am,and other unusual stars to H-alpha observations of early-typesupergiants and Be stars. The material discussed was obtained over thepast 40 years at a number of U.S. observatories and at the DominionAstrophysical Observatory in Victoria, B.C.
| Speckle interferometry of HIPPARCOS link stars. II
A second list is presented of stars that have been tested for theirsuitability as astrometric links between the Hipparcos satellite and theSpace Telescope. A speckle interferometer and autocorrelator were used,first on the 1.9-m telescope of the Mt. Stromlo and Siding SpringObservatories, and then, after discarding 16 stars showing evidence of abinary nature, on the Anglo-Australian 3.9-m telescope. Results aregiven for 123 stars. Combining the present list with the 1984 list, itis estimated that 29 percent of the original selection of 'cleanlooking' stars (on sky survey prints) are expected to be multiple at theresolution of the 3.9-m telescope, 0.03-0.7 arcsec.
| Lunar occultation summary. III
Observations of 242 photoelectric lunar occultation events studied atErwin W. Fick Observatory are reported. Approximately one-fourth ofthese are reappearances. From each observation are estimated the minimummagnitude differences between the observed object and possibleundetected companions. Occultation observations are given of 23 starsbrighter than 6th mag, including Alpha Vir, Beta-1 Sco, Mu Gem, Xi-2Sgr, Zeta Tau, Lambda Gem, and Beta Cap.
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| Сазвежђа: | Стрелац |
| Ректацензија: | 19h11m19.25s |
| Deклинација: | -20°20'50.1" |
| Apparent магнитуда: | 7.712 |
| Даљина: | 406.504 parsecs |
| Proper motion RA: | -3.2 |
| Proper motion Dec: | -9.3 |
| B-T magnitude: | 7.68 |
| V-T magnitude: | 7.71 |
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