The perihelion activity of comet 67P/Churyumov-Gerasimenko as seen by robotic telescopes

TL;DR

This study used robotic telescopes to observe comet 67P's activity around perihelion, revealing the timing and levels of dust and gas emissions, and comparing these with spacecraft data.

Contribution

It demonstrates the effectiveness of robotic telescopes in monitoring comet activity during limited visibility windows and provides new observational data around perihelion.

Findings

Peak activity occurred two weeks after perihelion.

Dust brightness matched previous predictions with no significant change.

Gas production rates were consistent with past measurements near perihelion.

Abstract

Around the time of its perihelion passage the observability of 67P/Churyumov-Gerasimenko from Earth was limited to very short windows each morning from any given site, due to the low solar elongation of the comet. The peak in the comet's activity was therefore difficult to observe with conventionally scheduled telescopes, but was possible where service/queue scheduled mode was possible, and with robotic telescopes. We describe the robotic observations that allowed us to measure the total activity of the comet around perihelion, via photometry (dust) and spectroscopy (gas), and compare these results with the measurements at this time by Rosetta's instruments. The peak of activity occurred approximately two weeks after perihelion. The total brightness (dust) largely followed the predictions from Snodgrass et al. 2013, with no significant change in total activity levels from previous apparitions. The CN gas production rate matched previous orbits near perihelion, but appeared to be relatively low later in the year.