TRAPPIST production rates of comet 220P/McNaught in outburst
ATel #17838; E. Jehin, J. Manfroid, S. Hmiddouch, K. Aravind (STAR Institute, University of Liege)
on 8 Jun 2026; 18:55 UT
Credential Certification: Emmanuel Jehin (ejehin@uliege.be)
The author reports that they obtained, using the TRAPPIST-North (Z53) telescope located in Morocco, observations of comet 220P on the nights of June 4 and 5, a few days after a large outburst of -6 mag was reported (ATEL#17829). They used broadband and cometary HB narrow-band filters (Farnham et al. 2000, Jehin et al. 2011) and computed preliminary production rates from extracted profiles at 10.000 km using a Haser Model (Vp=Vd=0.85/SQRT(rh))km/s) (Haser 1957). Zero Points were determined on close nights using standard stars. The proxy to the dust production rate A(0)f(rho) was estimated by profile fitting at 10.000 km (A'Hearn et al. 1984) and corrected for the phase angle (Schleicher 2007).
220P/McNaught
Date UT=2026-06-05, rh= 1.56 au, Delta= 1.56 au, DT= -9 days
Q(OH)= 8.40 +/- 1.26 E27 s-1
Q(CN)= 3.04 +/- 0.45 E25 s-1
Q(C2)=Â 5.50 +/- 0.83 E25 s-1
A(0)f(rho)(Rc)= 2305 +/- 21 cm
220P/McNaught
Date UT=2026-06-06, rh= 1.56 au, Delta= 1.55 au, DT= -8 days
Q(OH)= 6.52 +/- 0.98 E27 s-1
Q(CN)= 2.27 +/- 0.34 E25 s-1
Q(C2)=Â 4.05 +/- 0.61 E25 s-1
A(0)f(rho)(Rc)= 1915 +/- 25 cm
The production rates have dropped significantly between the two nights. The comet appears enriched in C2 with respect to CN. It also displays a narrow and intense dust tail, visible in all filters and in in particular in the dust continuum filters, which could indicate a fragmentation event.
Notations: rh= heliocentric distance (in au), Delta=geocentric distance (in au), DT= Time to perihelion. OH, NH, C3, CN, and C2 are the HB gaseous narrowband filters for the corresponding species, and BC, GC, and RC are the blue, green and red dust continuum filters (Farnham et al. 2000).
Acknowledgments: TRAPPIST is a project funded by the Belgian F.R.S.-FNRS under grant PDR T.0120.21 and the University of Liege. Observations were carried out from the ESO La Silla Paranal and Oukaimeden Observatory. We thank NASA, David Schleicher, and the Lowell Observatory for the loan of the HB comet filters. https://www.trappist.uliege.be/
