Structures in the dust coma of comet C/1999 T1 (McNaught-Hartley) from Jan. 26 to Feb. 05, 2001

Abstract

Aims. An in depth analysis of the images acquired in broad-band optical and infrared observations in the R , I , and J , H , K s bands of comet C/199T1 (McNaught-Hartley) acquired from Jan. 26 to Feb. 05, 2001 has been performed and is presented here.Methods. Beside the Laplace filtering technique applied to enhance structures in the dust coma of the comet McNaught-Hartley, we have also made use of the radial renormalization method to reveal large scale structures, usually broad jets.Results. We find that, contrary to other work, the comet did indeed show non-spherical structures besides the dust and ion tail. These structures, while not unambiguously detected when applying a Laplace filtering technique with small box sizes, have become evident by making use of radial renormalization techniques and larger box sizes in the Laplace filtering technique. This research note reports on these features.Conclusions. Geometrical analysis of the features and its evolution allows us to tentatively conclude that either the synodic spin period is very close to 24 h, or it has a rotation period much longer than 10 days, which could be indicative of the nucleus approaching an excited spin state, or the rotation axis is oriented such that an active area is permanently illuminated by the Sun and the jet is pointing toward or away from the observer.