Cometary Science Newsletter

April 2017
Michael S. P. Kelley (

Comet Notes

Brief observational reports or other notes related to specific comets. Limited to 1000 characters. The CSN is not intended to replace telegram services or other breaking news outlets.

Las Cumbres Outburst Monitoring of 41P/TGK

The Las Cumbres Observatory has awarded us 144 hours to use their global network of 1-meter telescopes to follow the activity of comet 41P/Tuttle-Giacobini-Kresak. The goal of this program is the early, automated detection of outbursts to enable rapid follow up.

Observations start April 1st and will continue until the end of August 2017. The comet will be observed every 48 hours using SDSS r' and g' filters. We will publish brightness data (Afr and magnitudes) on a dedicated website ( and will send frequent updates to the Minor Planet Center. Alerts will be submitted to CBET and the Yahoo Comets Mailing List. If you want to receive the alerts faster, send a message to Dennis Bodewits (

Refereed Articles

Abstracts of articles in press or recently published. Limited to 3000 characters.

Change in General Relativistic Precession Rates due to Lidov-Kozai oscillations in Solar System

  • Sekhar A. 1,2
  • Asher D. J. 2
  • Werner S. C. 1
  • Vaubaillon J. 3
  • Li G. 4
  1. Centre for Earth Evolution and Dynamics, University of Oslo, Norway
  2. Armagh Observatory and Planetarium, United Kingdom
  3. IMCCE, Observatoire de Paris, France
  4. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA

Both General Relativistic (GR) precession and the Lidov-Kozai mechanism, separately, are known to play an important role in the orbital evolution of solar system bodies. Previous works have studied these two mechanisms independently in great detail. However, both these phenomena occurring at the same time in real solar system bodies have rarely been explored. In this work, we find a continuum connecting the GR precession dominant and Lidov-Kozai like mechanism dominant regimes, i.e. an intermediate regime where the competing effects of GR precession and Lidov-Kozai like oscillations co-exist simultaneously. We find some real examples in the solar system in this intermediate regime. Moreover we identify a rare example amongst them, comet 96P/Machholz 1, which shows significant changes in the rates of GR precession (an order of magnitude higher than Mercury’s GR precession rate) due to sungrazing and sun colliding phases induced by Lidov-Kozai like oscillations. This comet’s combination of orbital elements and initial conditions (at the present epoch) favour this measurable rapid change in GR precession (at some points peaking up to 60 times Mercury’s GR precession rate) along with prograde-retrograde inclination flip (due to Lidov-Kozai like oscillations). Similar tests are performed for hundreds of bodies lying in the moderately low perihelion distance and moderately low semi-major axis phase space in the solar system, the present lowest perihelion distance asteroid 322P/SOHO 1, and further examples connected with 96P/Machholz 1 namely, the Marsden and Kracht families of sungrazing comets plus low perihelion meteoroid streams like Daytime Arietids (ARI) and Southern Delta Aquariids (SDA).

Monthly Notices of the Royal Astronomical Society (Published)

DOI: 10.1093/mnras/stx548