It is estimated by the researchers that the cluster is 443 light-years away by using radio telescopes and is at odds with the measurements taken through the
Hipparcos that shows the distance as 390 light-years.
Linking
Hipparcos and ICRF2 is essential in order to uniformize the reference independently of whether the source is visible (HCRF) or not (ICRF).
Further, I obtained access to the photometry of all of the stars observed by
Hipparcos [2].
These observations, re-analyzed with the
Hipparcos Catalogue (ESA 1997), were then used to determine the Earth Orientation Parameters (EOP) at 5-day intervals, covering the interval 1899.7 -1992.0 (Vondrak et al., 1998; Vondrak et al., 2000; Ron and Vondrak, 2001).
QUIZ OF THE DAY: 1 Eddie Irving; 2 A mountain range; 3 Cerne Abbas Giant; 4 Beetroot; 5 Joan of Arc; 6 When Harry Met Sally; 7 Michael Heseltine; 8
Hipparcos; 9 H.G.
ANSWERS: 1 Eddie Irving; 2 A mountain range; 3 Cerne Abbas Giant; 4 Beetroot; 5 Joan of Arc; 6 When Harry Met Sally; 7 Michael Heseltine; 8
Hipparcos; 9 H.G.
Among the topics are an overview of the Gaia Mission, a wide-field telescope in northern Arizona, astrometry and the virtual observatory, extracting sub-milliarcsecond parallaxes from
Hipparcos data, NASA programs, the future of astrometric education, and the current state of scientific imagers for astronomy.
We originally began observing HD199122 as a SPB based on its appearance in the list of such stars found through
Hipparcos data examination by Koen (MNRAS, 321, 44, 2001).
The observations by optical astrometry has recently been reanalyzed in the
Hipparcos reference frame (Vondrak 1999, Vondrak et al.
As part of the calibration effort for the WIRE satellite, investigation of the
Hipparcos database allowed stars of any given spectral type to be separated for magnitudes as faint as V=12.
The scientific promise of space exploration reached maturity with the results from Hubble, the Cosmic Background Explorer,
Hipparcos, Compton Gamma Ray Observatory, and their siblings.