Astrometric and photometric observations of six brightest trans-Neptunian objects at the Kyiv comet station

In this work we focused on observations of six trans-Neptunian objects (TNOs) whose apparent magnitudes are brighter than 20m. We present the results of astrometric and photometric observations of (134340) Pluto, (136108) Haumea, (136472) Makemake, (136199) Eris, (90482) Orcus, and (20000) Varuna obtained at the Kyiv comet station (Code MPC 585) in 2017-2019. For observations we used the 0.7-m (f/4) reflector AZT-8 with FLI PL4710 CCD camera and filters of Johnson-Cousins photometric system. From our images we measured the objects' astrometric positions, calculated apparent magnitudes in the BVRI (mostly R) bands using aperture photometry method, and found absolute magnitudes together with the colour indices in several bands. Analysing our results, we investigate the limitation on the astrometry and photometry of faint objects with the 0.7-m telescope.