Saturday21 February 20046:31pm MST2004-02-22 UTC 0131 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: An animation made from images supplied by Rob Matson from his precovery work that led to identifying 2004 DW ("packed" designation K04D00W) on a digitized scan of a glass plate exposed more than 52 years ago at Mt. Palomar, on 8 November 1951. It is blinked with another plate scan of the same sky location from 1992, with the object absent, showing that it wasn't a star or other background object on the 1951 plate. These plates and scans are ©Copyright Caltech/Palomar and AURA/STScI. Read below for more about this and other 2004 DW "precovery" work.

2004 DW update – part 1/2 Major News for 21 Feb. 2004 back top next  
2004 DW update

When Rob Matson found what he believed to be the newly discovered 2004 DW on a digitized plate from the National Geographic Society-Palomar Observatory Sky Atlas (POSS-I) from 8 November 1951, more than 52 years ago, the check was to look at another plate of the same sky location on a different date to make sure this object wasn't there. This to verify that his find wasn't actually a star or some other relatively "fixed" object beyond the Solar System. In the cover above, you see the 1951 plate blinked with a 1992 Second Palomar Observatory Sky Survey (POSS-II) plate. Not needed for the precovery work but necessary to create a blink animation, the 1992 image was scaled and rotated to match the 1951 image.

These archive images are available from the Digitized Sky Survey (DSS), and when an interesting newly-discovered object is announced there may be an international race among a small number of amateur astronomers to "precover" that object. With 2004 DW, Rob Matson, Reiner Stoss, and Maik Meyer all

independently turned in, and were credited in MPEC 2004-D15 with, archival findings from several observatories in 1951 and various other years up through 2002. And unrelated MPEC 2004-D28 today bore a correction that, "On MPEC 2004-D15, R. Matson should also have been credited with some of the measurements of 2004 DW from observatory code 608" (NEAT's Air Force telescope on Haleakala).

1954 find validated >>

More 2004 DW news coverage
See Major News yesterday and Thursday for A/CC's reports, images, orbital diagrams, and links to news coverage elsewhere.

More news coverage elsewhere

2004 DW update – part 2/2 Major News for 21 Feb. 2004 back top next  

1954 find validated   by Herbert Raab

After MPEC 2004-D15 noted that "the 1954 observation [of 2004 DW] was recorded as a star in the USNO-B1.0 catalogue," I checked the USNO-B1.0 and noted that the object, designated as 1121-0125248, was apparently detected on all five available plates: On the B and R plates of POSS-I, as well as on the B, R, and I plates of POSS-II. Obviously, if the object was still there when the POSS-II plates were exposed, the object cannot be 2004 DW.

I downloaded the relevant sections from the USNO-B and there seems to be no doubt that 2004 DW is indeed present on the POSS-I plates, and that this object is missing on the POSS-II plates.

Using the proper motion data provided by the USNO-B1.0, the position of 1121-0125248 is found to be within ~0.5" of the position reported for the 1954 observation of 2004 DW on MPEC 2004-D15. The magnitude listed in USNO-B1.0 is R=17.81mag and B=19.49mag, consistent with what one would expect for 2004 DW.

Now, by using the proper motion data to calculate the position for 1121-0125248 at the epoch of the POSS-II plates, it is apparent that the result matches that of the faint star, located about 7" west-southwest of 2004 DW in the POSS-I plates. Apparently, 2004 DW and that faint star were matched for the object identification and for the calculation of the proper motion when compiling the USNO-B data. The fainter magnitude listed for 1121-0125248 for the POSS-II plates (B=20.32mag, R=19.25mag) is also consistent with that hypothesis.

Therefore, I would conclude that the USNO-B does indeed include the 1954 observations of 2004 DW, that the 1954 position listed for 2004 DW on MPEC 2004-D15 is correct, and the data listed for 1121-0125248 in the USNO-B is invalid.

This is the author's report today to the Minor Planet Center. The 1954 precovery data was reported independently by Rob Matson and then by Reiner Stoss, who noted the USNO star catalog problem. The "B, R, and I" plates refer respectively to blue, red, and near-infrared. Stars do move and "proper motion" is the measure of that movement on the sky dome.–Ed.

News briefs – part 1/1 Major News for 21 Feb. 2004 back top next  
News briefs

California fireball?  A/CC has received a message, apparently from an Ann Hagerman, who writes:
I live in Westminster, California. Last night (Friday Feb 20, 2004) about 10:15pm I saw a fireball, meteor, or plane? Satellite burning up on reentry? It was visible to me for at least 30 sec to 60 sec. I heard nothing about it on the evening news or on any news Internet sites. It was solid orange and seemed to be moving from the west. A piece broke off, then eventually another, then it disintegrated. – If you saw this or know something about it, please tell A/CC.

Spitzer proposals:  The Spitzer Science Center (SSC) yesterday posted a 212Kb PDF with "Cycle-1 Proposal Statistics." It says 594 proposals have been received from 24 countries, and most from outside the Spitzer Space Telescope organization. Only 39 (6.6%) relate to the Solar System, with 12 for comets and 18 for "small bodies." Other solar systems (circumstellar disks and exoplanets) have 65 proposals.

Planetary defense:  The Atlanta, Georgia Journal-Constitution has a long article from yesterday, "Dodging a space bullet," about SpaceWorks Engineering, Inc. (SEI) with a $75,000 contract from the NASA Institute of Advanced Concepts (NAIC) for "purely a conceptual exercise" in how to defend against asteroid impacts. The company, "founded by Georgia Tech aerospace engineering professor John Olds and staffed entirely by Georgia Tech graduates," proposes in its NAIC Phase I abstract "a rapid and scalable solution consisting of hundreds or thousands of small, nearly identical spacecraft that will intercept the target body and conduct mass driver/ejector operations to perturb the target body’s trajectory." See also an SEI 30 October 2003 news release.

A Senate committee took testimony last Wednesday from Altair Development Corporation / NEO Safety International (transcript at SpaceRef.com ) telling of a grand plan to explore and prepare defenses against asteroids that "will be financed as a traditional real estate development," and asking for tax incentives and other government help.

Risk monitoring - part 1/1 Major News for 21 Feb. 2004 back top next  
Risk monitoring 21 Feb.

The Saturday Daily Orbit Update MPEC has observation of 2004 DC from Great Shefford Observatory in England this morning. Today NEODyS and JPL cut their impact solution counts considerably and slightly lowered their overall risk estimates for this near-kilometer size object.

Summary Risk Table - sources checked at 2309 UTC, 21 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 2/212013-207940-2.73-3.3204.714
JPL 2/212013-210247-2.53-3.1904.714
 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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