On the possibility of prompt processing of observations of a space debris object to calculate a preliminary orbit and ephemeris for the purpose of repeated observations on the current night

Abstract

The paper explores the conditions for a successful dynamic planning of the repeated observations of new space objects when the telescope operates in automatic mode. To organize the dynamic planning, we wrote software for determining the preliminary orbits and calculating the ephemeris for the near future in the format of a telescope operation scheduler. The computer program finds a preliminary orbit using the Laplace method and then improves it using the differential correction method. The program first uses the two-body problem formulas and then the SGP4 model to improve the orbit and calculate the ephemeris. This study considers 248 pairs of observation sets for 119 small-sized objects with an orbital semi-major axis from 7254 to 44 674 km, obtained during one night with the AT-64 telescope of the Crimean Astrophysical Observatory in 2022. Our software determined preliminary orbits by the first observation set and computed ephemeris for the time points of the second observation set for 234 pairs. Next, we estimated their quality by determining the angular distance (O — C) between the observed and calculated positions of the object. We accept that the preliminary orbit and ephemeris have a good quality if (O — C) < 45′, that is, the object falls within a field of view of the AT-64 telescope. As a result, we find that it is advisable to get the first observation set with a topocentric arc of more than 1° (and more than 5° in case of orbits with a semi-major axis of less than 20 000 km) and a duration of more than 3 minutes in order to successfully determine the preliminary orbit and compute a good-quality ephemeris during 60 minutes from the epoch of preliminary elements. But a repeated observation should be carried out within 30—40 minutes if objects have a high area-to-mass ratio.