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Hipparcos red stars in the HpV_T2 and V I_C systems
For Hipparcos M, S, and C spectral type stars, we provide calibratedinstantaneous (epoch) Cousins V - I color indices using newly derivedHpV_T2 photometry. Three new sets of ground-based Cousins V I data havebeen obtained for more than 170 carbon and red M giants. These datasetsin combination with the published sources of V I photometry served toobtain the calibration curves linking Hipparcos/Tycho Hp-V_T2 with theCousins V - I index. In total, 321 carbon stars and 4464 M- and S-typestars have new V - I indices. The standard error of the mean V - I isabout 0.1 mag or better down to Hp~9 although it deteriorates rapidly atfainter magnitudes. These V - I indices can be used to verify thepublished Hipparcos V - I color indices. Thus, we have identified ahandful of new cases where, instead of the real target, a random fieldstar has been observed. A considerable fraction of the DMSA/C and DMSA/Vsolutions for red stars appear not to be warranted. Most likely suchspurious solutions may originate from usage of a heavily biased color inthe astrometric processing.Based on observations from the Hipparcos astrometric satellite operatedby the European Space Agency (ESA 1997).}\fnmsep\thanks{Table 7 is onlyavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/397/997
| New periodic variables from the Hipparcos epoch photometry
Two selection statistics are used to extract new candidate periodicvariables from the epoch photometry of the Hipparcos catalogue. Theprimary selection criterion is a signal-to-noise ratio. The dependenceof this statistic on the number of observations is calibrated usingabout 30000 randomly permuted Hipparcos data sets. A significance levelof 0.1 per cent is used to extract a first batch of candidate variables.The second criterion requires that the optimal frequency be unaffectedif the data are de-trended by low-order polynomials. We find 2675 newcandidate periodic variables, of which the majority (2082) are from theHipparcos`unsolved' variables. Potential problems with theinterpretation of the data (e.g. aliasing) are discussed.
| The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
| Evaluation of a 512X512-Element Platinum Silicide Schottky-Barrier Infrared Image Sensor and Pilot Observations of Cygnus X Region
We present evaluation of the performance of Mitsubishi's 512X512 elementplatinum silicide (PtSi) Schottky-Barrier infrared image sensor forapplication to astronomical observation. An infrared camera system,incorporating the PtSi array, was built and its performance wasevaluated both in the laboratory and in observations. Dark current, DCstability, noise, quantum efficiency (QE), linearity, and uniformitywere measured. Results of a series of measurements show that the arrayhas potential capability for astronomical use. Several problems such aslow QE and "splashes" are discussed. To demonstrate the effectiveness ofthe array by using this infrared camera, we have mapped an area of 8X9square degrees of the Cygnus X region with a small telescope consistingof a silicon singlet lens. More than 1000 stars brighter than 6.5 mag inH-band were detected in the region. (SECTION: AstronomicalInstrumentation)
| Photoelectric photometry of M-type stars
UBVRI photoelectric photometry was obtained for 110 M-type starscontained in the Caltech Two-Micron Survey and the revised AFGL Catalog.Of the 110 stars, 58 have a color index (B-R) greater than or equal to 4mag. A graph is given of (V-R) versus (V-I) for the present stars.
| The Distribution of the BD M-Type Stars Along the Galactic Equator.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1958ApJ...128..510N&db_key=AST
| Bright Late M-Type Stars Near the Galactic Equator.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1954ApJ...120..118N&db_key=AST
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Besorolás csoportokba:
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Pozíciós és asztrometriai adatok
| Csillagkép: | Hattyú |
| Rektaszcenzió: | 20h44m58.45s |
| Deklináció: | +40°24'42.3" |
| Vizuális fényesség: | 8.514 |
| Távolság: | 943.396 parszek |
| RA sajátmozgás: | 8.5 |
| Dec sajátmozgás: | 6.9 |
| B-T magnitude: | 10.299 |
| V-T magnitude: | 8.662 |
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