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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
| Variable stars in the Tycho photometric observations. I. Detection
We present an original way to detect variable stars in the Tychophotometric observations. A modified Kolmogorov-Smirnov statistical testhas been constructed, based on a model of most of the satellite'sparameters, leading to the dispersion in the measurements. This allowsus to build a treatment taking into account truncated detections andcensored measurements, and to search for variability in the faint partof the catalogue. The selection threshold of variable stars has beencalibrated to minimize false alarm rate. Reliable results were thusobtained for stars as faint as 11 mag. One thousand and ninety-onesuspected variable stars have been listed, 407 of which are alreadyknown in Hipparcos, GCVS or NSV, and 684 of which are suspected variablestars to be identified soon.
| Stars with the Largest Hipparcos Photometric Amplitudes
A list of the 2027 stars that have the largest photometric amplitudes inHipparcos Photometry shows that most variable stars are all Miras. Thepercentage of variable types change as a function of amplitude. Thiscompilation should also be of value to photometrists looking forrelatively unstudied, but large amplitude stars.
| Hipparcos: The Stars
Not Available
| The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
| Near-infrared photometry of unidentified IRC stars. III - The Mira variables of spectral type M10
Less than two dozen visually bright Mira variables are known to exceedthe extremely late spectral type of M9.5 at minimum light. Near-infraredphotometry of the reddest unidentified sources in the Two-Micron SkySurvey has led to the identification and spectral classification of agroup of 38 additional M type Mira variables that reach M9.5, but whichon the average exhibit significantly larger amplitudes at 1 micron,longer periods, later spectral types, and redder near-infrared colorsthan the ones whose mean properties previously defined the coolest Miravariables. Periods and epochs of maximum light are given for 13 stars.Near-infrared magnitudes and photometric spectral types are also givenfor 107 additional unidentified IRC stars having less extreme spectraltypes, including 13 highly reddened early-M supergiants and four coolcarbon stars.
| Classification of 831 two-micron sky survey sources south of +5 degrees.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975AJ.....80.1011H&db_key=AST
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Osservazione e dati astrometrici
| Costellazione: | Corona Boreale |
| Ascensione retta: | 16h20m34.97s |
| Declinazione: | +34°37'40.1" |
| Magnitudine apparente: | 8.963 |
| Distanza: | 343.643 parsec |
| Moto proprio RA: | 0 |
| Moto proprio Dec: | -28.7 |
| B-T magnitude: | 10.552 |
| V-T magnitude: | 9.095 |
Cataloghi e designazioni:
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