Title: Application of the database of comet polarimetry (DBCP) for study the connection 
between physical and dynamic characteristics of selected comets.

Olena Shubina (Main Astronomical Observatory of National Academy of Science of Ukraine, Kyiv, Ukraine)

Polarimetry is effective method to determine the physical properties of comets. Comparison data 
of polarimetric observations with results of theoretical modeling and laboratory measurements 
follows us to determine the most likely composition, structure, and some other characteristics 
of comets. However, for this, sufficiently complete phase-angle dependencies of polarization 
in a wide range of phase angles and wavelengths is need. Unfortunately, it is impossible 
to get the phase-angle dependence of polarization for a particular comet in a wide range 
of phase angles. Therefore, one can use the synthetic phase-angle polarization dependence 
that based on all available observations of different comets. In our study, we used a new 
version of the database of comet polarimetry (EAR-C-COMPIL/VARGBDET-4-COMETPOL-V2.0.NASA 
Planetary Data System, 2017) that covers ranges of phase angles, helio- and geocentric 
distances 0.0-122.1_, 0.341-7.01 au and 0.01-6.52 au, respectively. We analyzed the 
phase-angle dependence of the degree of linear polarization of comets, as a function of wavelength, 
heliocentric and geocentric distance, dynamic characteristics and other parameters. This approach 
allows us to get the average polarization characteristics for different groups of comets including 
short-periodic, Halley-type and dynamically new comets with different places of origin in the Solar 
system and different evolution.
At present time it is also discussed the effect of gas emissions in the study of the dust coma of comets 
at short distances from the Sun using a broadband filters. This important question remains relevant 
in both photometric studies and polarimetric observations. It is necessary to carry out the analysis 
of the spectral data of bright comets obtained with broadband filters in order to evaluate and 
subsequently to subtract a gas contamination. It is the first step for correct estimates 
of the colour, values of the linear polarization and dust production alone.