Archive for January, 2011

Detailed statistic for the first half-year

Number of measurements: 79197

Measured objects: 18 550

Discovered objects: 228

Sky coverage: 4360 sq. degrees

Observing nights*: 128

* – include partial nights

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!

MPC statistic for December 2010 – January 2011

The new monthly MPC circular released – MPC 72993- 73612.

ISON-NM statistic for the previous month (November 29 – January 13):

Number of measurements: 36373

Measured objects: 8517

Discovered objects: 134*

Sky coverage: 1400 sq. degrees

Observing nights**: 36

* – interested object (comet C/2010 X1 (Elenin)

** – include partial nights

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

INTERNATIONAL ASTRONOMICAL UNION

New postal address:  Hoffman Lab 209; Harvard University;

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

CBATIAU@EPS.HARVARD.EDU ISSN 0081-0304

URL http://www.cbat.eps.harvard.edu/index.html

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

Asteroid 2010 JL33 shows signs of a large collision?

NASA/JPL-Caltech

December 11-12, 2010 radiolocation was carried out of the moderately large near-Earth asteroid 2010 JL33 using the Goldstone radio telescope of the Deep Space Network (Goldstone Solar System Radar). The asteroid was discovered May 6 of last year at Mt Lemmon Observatory, and it belongs to the class of potentially hazardous objects (PHA). Radiolocation helped to determine the size and shape of the heavenly body which you can see in the illustration at left.

The form of the asteroid is slightly extended, with length on the order of 1.8 km (1.1 mile). The period of rotation on its axis is 9 hours. The most interesting detail on the surface of the asteroid is a large crater, perhaps of impact origin.

At the moment of location, the asteroid was 8.5 million km from the Earth. Although it is bright enough, optical observations were hampered by the fact that 2010 JL33 had the Milky Way in the background the whole time. The observations are another success for the team of American radio astronomers conducting regular observations on the Goldstone and Arecibo radio telescopes.

January 2011
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