Complete text (abstract only):
We have selected from the Hipparcos catalogue (ESA 1997) a list of 307 very wide visual double stars, which can be used for performing an accurate astrometric calibration of CCD detectors mounted on telescopes. Angular separations are between 10 and 100 arcsec, mainly around 20" and less than 35".
Our list can be obtained from the Internet at the address
http://midas.oma.be/www_root/serverdoc/www/ccdlas.html
or it can be obtained from the authors directly. All information in our list was extracted, or computed from the Hipparcos catalogue. The format is simple containing one line per visual double star. (RA, Dec) coordinates of the component with the smallest RA value are given first. This component is obviously not always the primary. The epoch of the coordinates is the Hipparcos one: 1995.25. The following columns give V magnitudes and (B-V) colours of both components, their angular separation, and Hipparcos identifiers (HIC numbers).
For the information that will enable you to compute the current value of the angular separation of each wide visual double star used for calibration, you have to search in the main Hipparcos catalogue. Each component of the double stars in our list has a separate entry in this catalogue.
According to Sinachopoulos and van Dessel (1998), the Hipparcos catalogue contains some erroneous entries for wide visual double stars components as well. For this reason, it is advised to use at least three double stars of the list each time you calibrate your detector. All double stars in our list have been introduced to the Hipparcos mission by Brosche and Sinachopoulos (1988, 1989). In case you get problems or doubts on the correctness of the Hipparcos results for a particular double star, you can use information of these two publications for an additional control.
Acknowledgements
This research was carried out in the framework of the project »Pôles d'Attraction Interuniversitaires« P4/05, initiated and financed by the Belgian Federal Scientific Servics (DWTC/SSTC).
References
Brosche P., Sinachopoulos D., 1988, Bull. Inform. CDS 34
Brosche P., Sinachopoulos D., 1989, Bull. Inform. CDS 36
ESA 1997, The Hipparcos catalogue, ESA SP-1200
Sinachopoulos D., van Dessel E., 1998, A&A, in press
Bibliographical details:
Dimitrios Sinachopoulos, Edwin van Dessel, Michael Geffert: A list of Hipparcos very wide visual double stars for the astrometric calibration of imaging with CCDs. In: Peter Brosche, Wolfgang R. Dick, Oliver Schwarz, Roland Wielen (Eds.): The Message of the Angles - Astrometry from 1798 to 1998. Proceedings of the International Spring Meeting of the Astronomische Gesellschaft, Gotha, May 11-15, 1998. (Acta Historica Astronomiae ; 3). Thun ; Frankfurt am Main : Deutsch, 1998, p. 195-196.
Html-Version: Wolfgang R. Dick. Created: 21 Jan 1999