Long-lasting activity of asteroid (248370) 2005 QN 173

We present the results of observations of asteroid (248370) QN$_{173}$ obtained during July 2021 - January 2022 with three telescopes. Our analysis revealed the presence of the dust tail for about half of a year. The direct images of the asteroid were obtained with broad-band filters. No emissions were revealed in the spectra, and the spectrum of the asteroid closely matched that of a C-type asteroid. Created color and linear polarization variations along the tail were analyzed. The asteroid demonstrated a redder color compared to the Sun. Dramatic changes in dust productivity obtained in different filters were not detected. The $g-r$ color changes from $0.2^{m}$ to $0.7^{m}$ over the coma, and the linear polarization degree varies from about $1.2$\% to $0.2$\% and from $-0.2$\% to $-1.5$\% at the phase angle of $23.2^{\circ}$ and $8.16^{\circ}$. The total dust mass ejected until the latest observation on October 10 is $4.2 \times 10^7$~kg, with a maximum rate of 2.6~kg\,s$^{-1}$ based on the Monte Carlo modeling of the dust tail. The estimated asteroid size is 1.3~km. It is shown that large particles are concentrated around the nucleus, whereas smaller ones dominate in the tail. The evolution of (248370) QN$_{173}$ orbit and the orbits of the sample of the 464 short-periodic comets were followed. Ten of them approached the asteroid's orbit. These objects are not genetically related, despite the very close distance of their orbits for a relatively long time.Comment: pages 13; 5 tables; figures 1

Density, porosity and magnetic susceptibility of the Košice meteorite shower and homogeneity of its parent meteoroid

Bulk and grain density, porosity, and magnetic susceptibility of 67 individuals of Košice H chondrite fall were measured. The mean bulk and grain densities were determined to be 3.43 g/cm3 with standard deviation (s.d.) of 0.11 g/cm3 and 3.79 g/cm3 with s.d. 0.07 g/cm3, respectively. Porosity is in the range from 4.2 to 16.1%. The logarithm of the apparent magnetic susceptibility (in 10−9 m3/kg) shows narrow distribution from 5.17 to 5.49 with mean value at 5.35 with s.d. 0.08. These results indicate that all studied Košice meteorites are of the same composition down to ∼g scale without presence of foreign (non-H) clasts and are similar to other H chondrites. Košice is thus a homogeneous meteorite fall derived from a homogenous meteoroid.Peer reviewe