Friday20 February 20046:57pm MST2004-02-21 UTC 0157 back top next  

The Asteroid/Comet Connection's
daily news journal about
asteroids, comets, and meteors


Today's issue status: done
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Cover: Today's image of 2004 DW is a stack of three 30-second exposures made by the Starkenburg Observatory team (Martin Buchmann, Matthias Busch, and Felix Hormuth) Wednesday in confirming this object during a five-day run with the Madrid Observatory 1.52m telescope at Calar Alto in Spain. Technical details are the same as for the Astrometrica screen shot shown with news coverage yesterday. Two update MPECs were issued today for this object, with data now found all the way back to 1951 (see below).

Massive discovery – part 1/2 Major News for 20 Feb. 2004 back top next  
2004 DW (Darn Wide)

It is a nice coincidence that Pluto was discovered on 18 February 1930 by Clyde Tombaugh while examining plates from 21, 23, and 29 January at Lowell Observatory, whereas 2004 DW, which may prove to be the next-largest known object after Pluto circling the Sun, was discovered on February 17th and confirmed on the 18th, 74 years later.

The Minor Planet Center (MPC) this morning issued update MPEC 2004-D13 with a 0011 UTC time stamp with a 2004 DW position from Mt. Palomar from December 3rd and a new observation from Irmtraut Observatory yesterday, and restated the discovery observations both technically and for reattributing discovery credit. That credit is explained in a Caltech news release dated yesterday, "Planetary scientists find planetoid in Kuiper Belt; could be biggest yet discovered." Of the discoverers, Mike Brown is with Caltech, Chad Trujillo was formerly with Caltech, and David Rabinowitz is with Yale University.

The MPC issued another update, MPEC 2004-D15 with time stamp 1415 UTC today, showing not only new observations but also precovery positions going all the way back to 1951. This archival work is credited to Reiner Stoss, Maik Meyer, and Rob Matson, who tells A/CC: "After finding it in the first image, it was clear that the initial guess of a circular orbit was wrong — eccentricity was over 0.2 (0.2177). The result is a very Pluto-like orbit with a semimajor axis of 39.488 AU." Indeed, the MPEC announces that 2004 DW is in resonance with Neptune, which classifies it as a "Plutino" rather than as "Cubewano." And the new MPC absolute magnitude calculation of H=2.2 seems to support the upper range of early size estimates.

See below for orbit diagrams showing just how much the orbital solution has changed for this object.

more about 2004 DW >>

Massive discovery – part 2/2 Major News for 20 Feb. 2004 back top next  

<< continued from part 1

At right: Orbit diagrams for 2004 DW composited from EasySky screen shots to show the preliminary orbit solution and new less circular solution based on new observations found in the archives by Rob Matson, Maik Meyer, and Reiner Stoss going back as far as 8 November 1951 at Mt. Palomar, including positions in 1954, 1991-93, and 2001-02 at Palomar, Siding Spring, and Haleakala.

News coverage elsewhere
A/CC Major News broke the 2004 DW story at just before 4am EST yesterday based on the first Minor Planet Center MPEC. Here are some of the places where the story has gone today:

2004 DW old & new orbit solutions
News briefs – part 1/1 Major News for 20 Feb. 2004 back top next  
News briefs

Rosetta:  The Southwest Research Institute has a news release today (and photos) about two NASA-funded instruments it built for the Rosetta comet orbiter — the Alice ultraviolet imaging spectrometer and Ion and Electron Spectrometer (IES).

Meteor news:  Nature Science Update has an article today, "Meteorite molecules spin sugars." See also the Arizona State University news release today.

Main Belt news:  Rent-a-scope proprietor Arnie Rosner tells A/CC that Main Belt asteroid 2004 CU50 was discovered on February 15th by Ulrich Wolff in Germany operating a 0.3m telescope at New Mexico Skies. A check with the Minor Planet Ephemeris Service (MPES) shows that Wolff also caught it the next day, and that this object has been linked with observations from LONEOS on the 11th in Arizona and LINEAR on the 14th in New Mexico. Follow-up observations are "Desirable between 2004 Mar. 2-8." From its brightness (H=16.0), this object is estimated to be on the order of 2.14 km. (1.33 miles) wide.

Short warnings:  Thanks to Marco Langbroek for bringing to our attention a must-read report from David Morrison with Clark Chapman and Brian Marsden on Short Warning Times dated yesterday. It tells about the unusual situation that developed with asteroid 2004 AS1, which is almost better known by its temporary LINEAR discovery designation, AL00667 (see A/CC's brief February 9th report). The narrative is riveting.

The estimated size of asteroid AL00667, diameter 30 m, was small enough that no serious consequences were expected, but large enough that significant ground damage or possible injury could not be ruled out. The very limited data (from one night's observations) and the preliminary nature of the orbit at no time allowed an estimate of a possible impact site [during the next 36 hours]. The situation remained uncertain for several hours, until amateur astronomer Brian Warner, with a 20-inch aperture telescope in Colorado, searched the area where JPL calculations showed that the asteroid would have to be if it were on an actual collision course. Warner's observations were negative, showing that the true orbit for AL00667 did not intersect the Earth. 
Risk monitoring - part 1/1 Major News for 20 Feb. 2004 back top next  
Risk monitoring 20 Feb.

The Friday Daily Orbit Update MPEC has no observations for objects listed with impact solutions and currently in view.

Did you ever wonder if the risk monitors sometimes work with objects that haven't yet been observed long enough to obtain an IAU designation and discovery announcement? The answer to that is in David Morrison's report posted yesterday (see "Short warnings" above) about an object that briefly looked like it might destruct in the Earth's atmosphere before the confirmation process could be finished, a highly preliminary prediction that proved untrue.


Update:  The European Spaceguard Central Node has today posted observing campaigns for both 2004 DC and 2004 DD.

Summary Risk Table - sources checked at 2357 UTC, 20 Feb

Object

Assessment

Years

VI
PS
cum
PS
max
T
S
Arc 
days
 2004 DD NEODyS 2/192012-207417-4.97-5.3500.832
 2004 DC NEODyS 2/192006-207985-2.51-2.8502.013
JPL 2/182006-2103263-2.29-2.7302.013
 2004 BG121 NEODyS 2/142005-2080123-3.65-3.9400.934
JPL 2/13R E M O V E D
VI = count of "virtual impactors" (impact solutions)
See A/CC's Consolidated Risk Tables for more and maybe
  newer details, and check the monitors' links for latest info.
Note that only objects recently in view are shown here.
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