Results of baseline observations of asteroid 87 Sylvia on October 29, 2019

Abstract

On 29 October 2019 the Pulkovo Observatory observed the occultations of the the star TYC 1932-469-1 (Gaia DR2 Source id = 679856115656562048) by asteroid 87 Sylvia. The observation was made with the one-meter reflector telescope. Simultaneously, the asteroid 87 Sylvia was surveyed using the MTM-500M telescope located at the GAO RAS Mountain Astronomical Station where a visible close approach was observed. Based on this example, the article discusses the possibility of improving the accuracy of ground based astrometric observations and obtaining «instantaneous» parallaxes to refine the ephemeris by means of baseline observations of the occultations and the apparent close approaches. The paper demonstrates that the method allows to obtain the coordinate accuracy of the order of 0.010 arcsec, which in this case gives a parallax of the asteroid with the accuracy of 0".03 arcsec. Comparison with the existing ephemerides showed a high degree of convergence.