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Comet Hale-Bopp and the Diffuse Interstellar Lines
As an illustration of the manner in which serendipitous events can beused to obtain useful scientific information, the reasons for observing,spectroscopically, the appulse of HD 12895 and Comet Hale-Bopp arediscussed and the conclusions of the study are briefly presented.
| Radial velocities. Measurements of 2800 B2-F5 stars for HIPPARCOS
Radial velocities have been determined for a sample of 2930 B2-F5 stars,95% observed by the Hipparcos satellite in the north hemisphere and 80%without reliable radial velocity up to now. Observations were obtainedat the Observatoire de Haute Provence with a dispersion of 80Ä,mm(-1) with the aim of studying stellar and galactic dynamics.Radial velocities have been measured by correlation with templates ofthe same spectral class. The mean obtained precision is 3.0 km s(-1)with three observations. A new MK spectral classification is estimatedfor all stars. Based on observations made at the Haute ProvenceObservatory, France and on data from The Hipparcos Catalogue, ESA.Tables 4, 5 and 6 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr or viahttp://cdsweb.u-strasbg.fr/Abstract.htm
| A search for the presence of diffuse interstellar bands in the coma of Comet Hale-Bopp
The spectrum of HD 12895 (B8, V=8.2) was observed on 1997 April 3 as thenucleus of Comet Hale-Bopp passed at a minimum star-nucleus separationof 31 arcsec. Spectrograms were obtained at R=45 000 using the Keck IHIRES. No convincing enhancement of the equivalent width of any of thediffuse interstellar bands at 4726, 4779, 5780, 6269 and 6613 A wasfound during this event. This negative result is compatible with ourprevious lower resolution observations of Comet Halley in 1986. It isconcluded that the carriers of these particular bands, if initiallypresent in the nucleus of Hale-Bopp, either were not carried into thecoma with the evaporating volatiles, or were modified or destroyed bythe solar radiation field while in transit.
| Radial-velocity measurements. V - Ground support of the HIPPARCOS satellite observation program
The paper presents data on 1070 radial velocity measurements of starsdistributed in 39 fields measuring 4 deg x 4 deg. The PPO series ofFehrenbach et al. (1987) and Duflot et al. (1990) is continued using theFehrenbach objective prism method.
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