What is the fine-grained topic of the following text: Comet 67P/Churyumov–Gerasimenko seen towards the constellation of Ophiuchus (note that from the vantage point of Earth, both the comet and Rosetta are presently in Sagittarius), with the globular cluster M107 also clearly visible in the field of view. Only return the topic.
Observation of Comet 67P/Churyumov–Gerasimenko and its position in relation to constellations and star clusters.