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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.
| New optical positions and proper motions of late type stars associated with SiO masers
The 33 cm astrograph of the Bordeaux Observatory has been used to derivewith respect to AGK3 reference stars, accurate positions of late typevariable stars variable stars associated with strong SiO maser emission.It is suggested that selected maser stars can be used to link theHIPPARCOS system and the VLBI extragalactic reference frame. The propermotions of the program (SiO) and reference stars are derived and, forthe program stars, are compared to the McCormick catalog of propermotions.
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Herkul |
| Sað Açýklýk: | 16h23m04.58s |
| Yükselim: | +19°30'21.5" |
| Görünürdeki Parlaklýk: | 7.386 |
| Uzaklýk: | 180.832 parsek |
| özdevim Sað Açýklýk: | -11.7 |
| özdevim Yükselim: | 12.1 |
| B-T magnitude: | 7.607 |
| V-T magnitude: | 7.405 |
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