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Comet 133P/ (7968) Elst-Pizarro (1996 N2)
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Comet 133P/ (7968) Elst-Pizarro (1996 N2) is at Opposition (2.447 AU) on the 25th November 2014 



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Comet 133P/Elst-Pizarro (1996 N2)
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Comet 133P/Elst-Pizarro (1996 N2) makes its closest approach to the Earth (2.444 AU) on the 20th November 2014

Ephemeris

Date    TT    R. A. (2000) Decl.     Delta      r    Elong.  Phase   Mag
2014 11 19    04 07 37.0 +18 58 24   2.4440  3.4266   172.6     2.1
2014 11 20    04 06 47.1 +18 56 03   2.4438  3.4278   173.7     1.8
2014 11 21    04 05 57.0 +18 53 41   2.4438  3.4290   174.9     1.5
2014 11 22    04 05 06.7 +18 51 18   2.4441  3.4302   176.0     1.2
2014 11 23    04 04 16.4 +18 48 55   2.4448  3.4314   177.0     0.9
2014 11 24    04 03 26.1 +18 46 32   2.4457  3.4326   177.8     0.6
2014 11 25    04 02 35.8 +18 44 09   2.4470  3.4338   178.1     0.6
2014 11 26    04 01 45.5 +18 41 47   2.4486  3.4351   177.7     0.7
2014 11 27    04 00 55.4 +18 39 24   2.4505  3.4363   176.8     0.9
2014 11 28    04 00 05.5 +18 37 02   2.4527  3.4375   175.8     1.2
2014 11 29    03 59 15.8 +18 34 41   2.4552  3.4387   174.7     1.5
2014 11 30    03 58 26.4 +18 32 20   2.4580  3.4398   173.5     1.8


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133P/(7968) Elst-Pizarro
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Title: Hubble Space Telescope Investigation of Main-Belt Comet 133P/Elst-Pizarro
Author: David Jewitt, Masateru Ishiguro, Harold Weaver, Jessica Agarwal, Max Mutchler, Steven Larson

We report new observations of the prototype main-belt comet (active asteroid) 133P/Elst-Pizarro taken at high angular resolution using the Hubble Space Telescope. The object has three main components; a) a point-like nucleus, b) a long, narrow antisolar dust tail and c) a short, sunward anti-tail. There is no resolved coma. The nucleus has a mean absolute magnitude H_V = 15.70+/-0.10 and a lightcurve range 0.42 mag., the latter corresponding to projected dimensions 3.6 x 5.4 km (axis ratio 1.5:1), at the previously measured geometric albedo of 0.05+/-0.02. We explored a range of continuous and impulsive emission models to simultaneously fit the measured surface brightness profile, width and position angle of the antisolar tail. Preferred fits invoke protracted emission, over a period of 150 days or less, of dust grains following a differential power-law size distribution with index 3.25 < q < 3.5 and having a wide range of sizes. Ultra-low surface brightness dust projected in the sunward direction is a remnant from emission activity occurring in previous orbits, and consists of the largest (>cm-sized) particles. Ejection velocities of one micron-sized particles are comparable to the ~1.8 m/s gravitational escape speed of the nucleus, while larger particles are released at speeds less than the gravitational escape velocity. The observations are consistent with, but do not prove, a hybrid hypothesis in which mass loss is driven by gas drag from the sublimation of near-surface water ice, but escape is aided by centripetal acceleration from the rotation of the elongated nucleus. No plausible alternative hypothesis has been identified.

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Comet 133P/Elst-Pizarro is at Opposition (1.776 AU) on the 4th September, 2013.



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Comet 133P/Elst-Pizarro makes its closest approach to the Earth (1.772 AU) on the 30th August, 2013



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Comet 133P/Elst-Pizarro is at Perihelion (2.650 AU) on the 9th February, 2013.



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Ephemeris

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase   Mag
2013 02 08    20 05 17.9 -19 32 10   3.5564  2.6500    19.9     7.3
2013 02 09    20 07 09.3 -19 26 43   3.5520  2.6500    20.4     7.5
2013 02 10    20 09 00.4 -19 21 11   3.5475  2.6500    21.0     7.7
2013 02 11    20 10 51.3 -19 15 35   3.5429  2.6500    21.6     7.9
2013 02 12    20 12 42.0 -19 09 55   3.5382  2.6500    22.1     8.1
2013 02 13    20 14 32.3 -19 04 11   3.5334  2.6500    22.7     8.3
2013 02 14    20 16 22.4 -18 58 24   3.5284  2.6501    23.3     8.5
2013 02 15    20 18 12.2 -18 52 33   3.5234  2.6501    23.8     8.7
2013 02 16    20 20 01.7 -18 46 38   3.5182  2.6501    24.4     8.9
2013 02 17    20 21 50.9 -18 40 39   3.5130  2.6502    25.0     9.1
2013 02 18    20 23 39.9 -18 34 37   3.5076  2.6503    25.5     9.3
2013 02 19    20 25 28.5 -18 28 32   3.5021  2.6503    26.1     9.4
2013 02 20    20 27 16.8 -18 22 23   3.4965  2.6504    26.7     9.6


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Comet 133P/Elst-Pizarro makes its closest approach to the Earth (1.863 AU) on the 14th May, 2012.



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Half Comet-Half Asteroid Confirmed Not a Fluke
Back in 1996, astronomers discovered a strange object in the asteroid belt. They decided it was either a "lost" comet or an icy asteroid, as it ejected dust like a comet but had an orbit like an asteroid. No one had ever seen anything like the object, called 133P. Ever since it was found, astronomers have wondered if it was just an oddity - one of a kind. We now know it is not, and the discovery of more of these half asteroids/half comets means there is a new class of objects in our solar system.


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Title: The Hawaii Trails Project: Comet-Hunting in the Main Asteroid Belt
Authors: Henry H. Hsieh

Supplementary data

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