INDEPENDENT ANALYSIS OF μδ DATA OF ILS AND INDLS CATALOGS TO OBTAIN THE SPIN OF THE BRIGHT GAIA DR2 REFERENCE FRAME

Serbian Astronomical Journal

article

Damljanović G.¹  Stojanović M.¹  Aleksić J.² 

[1] Astronomical Observatory;Department of Astronomy, Faculty of Mathematics, University of Belgrade

关键词: Catalogs;    Surveys;    Proper motions;    Reference systems;   

DOI  :  10.2298/SAJ210428002D

来源: Astronomical Observatory, Department of Astronomy, Belgrade

【 摘 要 】

The Gaia DR2 reference frame should be without relative rotation to the quasars(QSOs) and consistent with the International Celestial Reference System (ICRS). For the faint part ofDR2 (stars with Gaia magnitude G ≥ 16) that task was done via Gaia’s observations of QSOs (G ≥ 17mag), but the bright DR2 (G ≤ 13 mag) is difficult to validate and it rotates relative to the faint DR2at rate of the order of 0.1 mas/yr. Very bright DR2 stars (G ≤ 6 mag) mostly have inferior astrometry.Here, the aim is to determine two spin components (ωX and ωY ) of the bright DR2 using InternationalLatitude Service (ILS, for 387 stars) and independent latitude stations (INDLS, for 682 stars) catalogsof proper motion in declination µδ; both are referred to the Hipparcos reference frame and their starsare mostly from 4 to 8 mag in the V-band (critical part of DR2). Also, using the new Hipparcos(NHIP) values µδ for ILS and INDLS stars, we can see that the merit of the ILS and INDLS is thelong time baseline (∆t ≈ 90 years) important for µδ because the standard deviation of µδ is opposite to∆t. Applying the least squares method (LSM) to the differences of µδ between two catalogs (ILS−DR2,INDLS−DR2, etc.), our results support the mentioned spin. The 3σ criterion and Tukey’s fences methodwere used to reject some stars, the Abbe criterion to explain the variability in ILS−DR2 and other µδdifferences, and the Shapiro-Wilk test to check the standard distribution of differences. The obtainedωY is significant at the 2σ level, and the ILS and INDLS catalogs could be useful for validation of thebright reference frame of Gaia DR2.

【 授权许可】

CC BY-NC-ND