TRAPPIST Narrow Band Survey of Bright Long Period Comets in 2022-2023

Introduction: Comets are remnants of the early Solar System, as they formed from icy and dusty material 4.6 billion years ago. Therefore, their study provides valuable information on the physico-chemical environment of the early Solar System. The dynamical distribution of comets has evolved since then, most notably due to the migration of giant planets. Today, the main reservoirs are the Oort cloud, source of the isotropic Oort cloud comets (OCCs) or long period comets (LPCs) with orbital periods exceeding 200 years, and the Kuiper Belt, source of the Jupiter Family Comets (JFCs). TRAPPIST Observations: We used both TRAPPIST-North (TN) and-South (TS) [1], to observe and follow LPCs along their orbits. These telescopes are equipped with standard Johnson-Cousin B, V, Rc, and Ic filters, as well as narrow-band filters optimized for observing emission bands of volatiles found in comets [2]. These filters isolate emission signature of OH (309.7 nm), NH (336.1 nm), CN (386.9 nm), C3 (406.3 nm), C2 (513.5 nm), and four continuum-free wavelengths (UC at 344.9 nm, BC at 445.3 nm, GC at 525.9 nm, and RC at 713.3 nm). TN and TS allow us to continuously monitor those comets in both hemispheres, before and after perihelion. In this work, we investigated the activity and composition changes of the brightest LPCs between 2022 and 2023 using both TRAPPIST telescopes. The LPCs investigated are C/2022 E3 (ZTF), C/2020 V2 (ZTF), C/2019 U5 (Pan-STARRS), and C/2022 A2 (Pan-STARRS), some were also observed by other programs on large telescopes for detailed chemical composition analysis from the UV to the radio domains. We analyzed the evolution of production rates and chemical mixing ratios of OH, NH, CN, C2, and C3 at different heliocentric distances. Additionally, we computed A(0)fp, a proxy for dust activity, during the comets' journey towards the inner Solar System.