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Trying to find the more marginal comets

Presentation #113.08 in the session Asteroids: Observational Surveys (Oral Presentation)

Published onOct 23, 2023
Trying to find the more marginal comets

The Pan-STARRS survey currently discovers about one third of new comets. However, in some cases, their initial detection appears marginally active, and the measurement of such activity is often subjective to the person who reviews them. Follow-up observations using the Canada-France-Hawaii Telescope almost always confirms that these marginal discoveries are in fact comets, which implies our selection criteria could be improved. We basically want to know: how many faint comets do we miss? And how many comets found by the other survey telescopes could have been discovered sooner, allowing for additional observations to better characterise them? We have devised a parallel pipeline to reprocess “chip” images corresponding to recent unlinked observations relegated to the Isolated Tracklet File. By fitting their PSF profiles using more sophisticated techniques than were previously implemented, we aim to better assess (quantitatively vs qualitatively) whether we are indeed missing many objects exhibiting low level activity. There are two important cases of comets we wish to find: Great comets for public outreach purposes, and Near Earth Comets which might pose an impact risk to the Earth, and possibly produce meteoroid streams which if observed as ablating meteors, could help constrain the properties of their parent objects. However, our work also has many other important benefits, such as being able to better assess the curvature of low scoring objects (allowing us to find objects close to the Earth that are hidden in plain sight — see the talk by Veres et al.), and even trying to search for much slower moving objects than the current Pan-STARRS image processing pipeline allows.

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