Posts Tagged ‘P/2006 U1 (LINEAR)’

P/2006 U1 – evolution of the orbit of a pinpoint comet

R. Ligustri, F. Romanello / CARA

I want to return again to the recently recovered comet P/2006 U1 (LINEAR). There are several reasons. First, this comet comes close to the Earth and merits a detailed analysis of the future evolution of its orbit. Second, this is a very unusual long-period comet. Looking at the picture at the left, you will understand what I have in mind.

A little history: the comet was discovered as an “asteroid” October 19, 2006 by the American sky survey Lincoln Near Earth Asteroid Research (LINEAR). After being placed on the NEOCP confirmation page, several observers commented on the presence of a long tail for this new object. The coma was very compact. The external appearance of the new comet was similar to 133P/Elst-Pizarro.

Let us return to the evolution of the comet’s orbit. After its recovery, the observation arc was now 4.24 years. Calculations were made with the help of the programming complex EPOS (V.N. Lvov, S.D. Tsekmeister) and numerical ephemerides DE406. Below is shown a graph of the osculating elements – semimajor axis (a), eccentricity (e), orbital inclination (i), perihelion distance (q), for a period of 2000-3000 years.

So what can we conclude from this graph? First – from the beginning of this century the orbital elements of the comet have begun to seriously change. The orbital inclination, after falling to a minimum value of 7.22° in the 70s of this century at the moment of closest approach of the comet to the Earth, April 26, 2076 (?=0.0505 a.u. noted on the graph), will grow over the course of the next seven centuries, achieving a magnitude of 37.7° by the middle 70s of the 28th century.

Along with the increase in inclination, the perihelion distance will also increase (the comet will pass farther from the Sun), although perihelion will not pass the limit of the Earth’s orbit (qmax = 0.81 a.u.). Along with that, the size of the eccentricity will begin to decrease to e=0.71, so the comet’s orbit will still remain eccentric. However, the most important outcome: after the 2076 apparition, the comet will begin to pass farther from the Earth. After 200 years, the distance of passage will increase by a factor of 10. Comet P/2006 U1 will not be hazardous to the Earth for the forseeable future.

In the current passage of 2011, there have already been several observations. All were made at our observatory. In the near future we will return to this comet to observe chages in its cometary activity. Will it delight us this time with its unusual tail? We will soon see!

Recovery of comet P/2006 U1 (LINEAR)

L. Elenin / ISON-NM

January 14th, at the ISON-NM Observatory, we recovered a short-period comet of the Jupiter family – P/2006 U1 (LINEAR). The observations were made under the auspices of the ROCOT program. This is the second appearance of this comet; the last time its perihelion date was August 28, 2006.

On the images, the comet was off from the calculated coordinates by 9.2 arc minutes which was significant. At this moment, the comet is quickly approaching Earth, and will come within 0.775 a.u. on March 12-13, 2011. Its maximum brightness of mag. 17 will be in the first half of April. The comet’s period of revolution around the Sun is 4.63 years.

It is worth noting that Comet P/2006 U1 is a near-Earth object. The minimum distance at which its orbit crosses Earth’s orbit is 0.0526 a.u. (7.89 million km.). Taking into account its absolute magnitude M1 = 16.3, the comet could be considered a potentially hazardous object (PHO) if its MOID were less by just 0.0026 a.u.

The last time Comet P/2006 U1 was observed was about 4 years ago – January 13, 2007. In the near future it should receive its permanent number – 249P/LINEAR.

Below is shown the circular from the International Astronomical Union (IAU), dedicated to this event.

Circular No. 9194

Central Bureau for Astronomical Telegrams


New postal address:  Hoffman Lab 209; Harvard University;

20 Oxford St.; Cambridge, MA  02138; U.S.A.



Prepared using the Tamkin Foundation Computer Network

COMET P/2011 A4 = P/2006 U1 (LINEAR)

L. Elenin, Lyubertsy, Russia, reports his recovery of P/2006

U1 (cf. IAUC 8763) on images obtained remotely at the ISON-NM

Observatory near Mayhill, NM, USA; his astrometry is provided

below, and the object is described as slightly diffuse with no

visible tail.

2011 UT             R.A. (2000) Decl.       Mag.   Observer

Jan. 14.51322   14 14 00.58   -21 18 30.4   19.5   Elenin

14.52034   14 14 01.76   -21 18 36.5   19.3     “

14.52751   14 14 02.94   -21 18 43.5   19.7     “

15.46672   14 16 45.65   -21 32 55.8   19.3     “

15.49142   14 16 49.95    -21 33 18.1   19.4     “

15.51633   14 16 54.19    -21 33 41.2   19.1     “

The indicated correction to the prediction by S. Nakano (2010/2011

Comet Handbook) is Delta(T) = +0.24 day.  The following improved

elliptical elements by the undersigned are from 360 observations,

2006 Oct. 19-2011 Jan. 15 (mean residual 0″.46).

Epoch = 2011 Apr. 29.0 TT

T = 2011 Apr. 16.08061 TT        Peri. =  64.22882

e = 0.8160435                    Node  = 240.47143 2000.0

q = 0.5108788 AU                 Incl. =   8.42516

a =  2.7771717 AU   n = 0.21296095   P =   4.63 years

(C) Copyright 2011 CBAT

2011 January 17                (9194)            Daniel W. E. Green

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