Sunday3 October 20049:53pm MDT2004-10-04 UTC 0353 last
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The Asteroid/Comet Connection's
daily news journal about
asteroids, comets, and meteors

Today's issue status: done


Cover: Prediscovery imagery of small object 2002 EA (long path) located by Josep Julia Gomez in the archive of NEAT's Mt. Palomar observations and reported this past week from the morning of 2 March 2002. Rafael Ferrando at Pla D'Arguines Observatory in Spain caught 2002 EA that night, the third of six NEO discoveries made from amateur observatories in 2002 (see his discovery story in English or Spanish). Gomez writes that he has been working in the archives for several months to find earlier positions for asteroids discovered by “Rafa Ferrando, friend and prolific discoverer. This prediscovery has been the most exciting, although not the most difficult.” More info below. The object with the short path in this three-frame composite image is Main Belter 2002 CY157.

Small objects – panel 1/2 Major News for 3 Oct. 2004 back top next  

Small objects
Discovery & follow-up for 27 Sept. – 3 Oct. 2004

Despite the full Moon, this past week was a good one for keeping track of small asteroids (defined at right), even if no new asteroid discoveries were announced, small or large. Ten observatories managed to participate in observing six small objects, of which one, 2004 RQ252, had impact solutions until this morning. Observations were also reported in the last seven days for two more observed in mid-September.

Prediscovery (discovery apparition), precovery (previous apparition), and other observations found in archives for small asteroids are rare. In fact, the last reported here was on June 13th for 1998 HG49, although more than two dozen were reported in March and April. And so we make special note that Tuesday's Daily Orbit Update MPEC reported prediscovery positions found in the archives by Josep Julia Gomez for 2002 EA (see imagery above and more info below).

One small object was known to have made a fairly close flyby this past week, 2004 SY4 at 8.3 lunar distances (LD) on Wednesday. For the coming week, the closest predicted passage is by 2004 SC56 at 13.6 LD tomorrow, Monday.

<< previous report | skip table | Small objects table >>

What’s so big about “small objects?” If an asteroid’s orbit brings it to within 0.05 astronomical units (AU) of Earth's orbit, it is categorized as “potentially hazardous” unless it has an absolute magnitude H greater than 22.0, which corresponds to a diameter on the order of 135 meters/yards. Larger H means less bright, thus smaller size. And 0.05 AU is about 19.5 times the distance between Earth and Moon (0.00256 AU). To be discovered and tracked, such objects usually must come close (a few are Earth’s nearest neighbors, coming closer than the Moon). They are exposed pieces of distant asteroid populations, and they have within their own population tomorrow’s meteors. And their discovery and follow-up represents today’s best amateur and professional asteroid observing work. Diameter & Earth MOID: In the following observation summary table, the stated diameters are rough best estimates from a standard but very inexact H-to-size formula using H (absolute magnitude, or brightness) from the JPL NEO Orbital Elements page, source also for Earth MOID (minimum orbital intersection distance). Current Minor Planet Center H is also given, along with the original H from each object's discovery MPEC. Other sources: Planetary MOIDs are from Lowell Observatory. Priorities and visibilities are from the European Spaceguard Central Node (SCN). And flyby distances and times are from the JPL Close Approach Table. See also the Sormano Observatory SAEL (H>22.0 and Earth MOID<0.015 AU), and NEODyS listings have yet another H calculation.
Small objects – panel 2/2 (table) Major News for 3 Oct. 2004 back top next  

Small object observation summary for 27 Sept. – 3 Oct. 2004

H = absolute magnitude (brightness), from which size is roughly estimated   —   m/yd = meters/yards   —   [cross index]
All objects had observations reported last week. Those on a light-blue background had observations from only before the week.

European Spaceguard Central Node
2004 RN111
39 m/yd24.6725.025.2 2004-R730.034409 AU
2004 RN111 was reported this past week as observed on 16 Sept. by LONEOS, within the existing 5.699-day observation arc.
2004 SY4
45 m/yd24.3624.424.3 2004-S260.016995 AUUrgent, visibility ends 12 Oct.
2004 SY4 was observed on 25 and 26 Sept. with the Australian National University (ANU) 1m telescope, adding 4.424 days to what had been an observing arc of 2.647 days. This object passed Earth at 8.4 lunar distances (LD) at 1935 UT on 29 Sept.
2004 RC80
46 m/yd24.3424.424.6 2004-R510.043624 AUUrgent, visibility ends 6 Oct.
2004 RC80 was reported this past week as observed on 16 Sept. by the Nordic Near-Earth-Object Network of Spaceguard (NEON) on La Palma, within the existing 9.725-day observing arc.
2004 SR
59 m/yd23.8123.823.7 2004-S140.025372 AUUseful, visibility ends 29 Oct.
2004 SR was observed on 1 Oct. by Consell Obs.
2004 SC56
85 m/yd23.0122.922.9 2004-S650.011544 AUUrgent, visibility ends 16 Oct.
2004 SC56 was observed on 26 Sept. by Naef Obs., on 28 Sept. by University Hills Obs., Naef Obs., and Linhaceira Obs., on 29 Sept. by Linhaceira Obs., on 1 Oct. by Robert Hutsebaut using a Rent-A-Scope telescope at New Mexico Skies and by Consell and Pla D'Arguines observatories, and on 2 Oct. by University Hills Obs. It has an MOID of 0.019 AU with Venus and will pass Earth at 13.6 LD on 4 Oct.
2004 SA20
102 m/yd22.6022.922.9 2004-S400.032962 AUNecessary, visibility ends 22 Oct.
2004 SA20 was observed on 26 Sept. with the ANU 1m telescope, adding 4.283 days to what had been a 1.035-day observing arc. This object has MOIDs of 0.031 AU with Venus and 0.001 AU with Mars.
2002 EA
112 m/yd22.4022.422.4 2002-E100.035319 AU
2002 EA was reported this past week as having been observed early on 2 March 2002 by NEAT from Mt. Palomar. This was discovered in the NEAT archives by Josep Julia Gomez (see image above), and added 0.509 day to the previous 8.938-day observation arc.
2004 RQ252
116 m/yd22.3222.322.3 2004-S050.00009.2 AUUrgent, visibility ends 12 Oct. / campaign
2004 RQ252 was observed on 25 and 26 Sept. with the ANU 1m telescope, and was picked up again 5.843 days later by Hunters Hill Obs. and then Leura Obs. on 2 Oct. This object had impact solutions that were all removed by NEODyS and JPL on 3 Oct. (see below). Both risk monitors previously had removed all their solutions on 20 Sept., but NEODyS had reposted this object on 25 Sept. and JPL on 28 Sept. It has an MOID of 0.045 AU with Venus and will pass Earth at 21.3 LD on 9 Oct.
2004 RE84
132 m/yd22.0422.222.6 2004-R550.020014 AUUrgent, visibility ends 10 Oct.
2004 RE84 was observed on 25 Sept. with the ANU 1m telescope, bringing this object's observing arc to 15.236 days, which was expanded by another 5.716 days when Desert Moon Obs. caught it on 1 Oct. It has an MOID of 0.029 AU with Venus and will pass Earth at 24.1 LD on 6 Oct.

  Small object observation cross index   [table top]
ObjectObserved by MPC code
2002 EA644
2004 RC80J50
2004 RE84413 & 448
2004 RN111699
2004 RQ252413, E14 & E17
2004 SA20413
2004 SC56176, 938, 941, A13, G72 & H06
2004 SR176
2004 SY4413
CodeObservatoryObjects observed (days)
176Consell Obs.2004 SC56 & 2004 SR
413Australian National University (ANU) 1m telescope2004 RE84, 2004 RQ252(2), 2004 SA20 & 2004 SY4(2)
448Desert Moon Obs.2004 RE84
644NEAT/Palomar2002 EA
699LONEOS2004 RN111
938Linhaceira Obs.2004 SC56(2)
941Pla D'Arguines Obs.2004 SC56
A13Naef Obs.2004 SC56(2)
E14Hunters Hill Obs.2004 RQ252
E17Leura Obs.2004 RQ252
G72University Hills Obs.2004 SC56(2)
H06Robert Hutsebaut/New Mexico Skies2004 SC56
J50Nordic Near-Earth-Object Network2004 RC80
News briefs – panel 1/1 Major News for 3 Oct. 2004 previous
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News briefs

Deep Impact news:  Ball Aerospace has a news release dated October 1st stating that the Deep Impact comet flyby and impactor spacecraft have “completed the final environmental testing phase before launch, scheduled for December 2004.” This included “thermal vacuum, electromagnetic conductance, electromagnetic interference, vibration and acoustic testing.”

The High Resolution Imager aboard the Flyby spacecraft will be one of the largest interplanetary telescopes ever flown in order to record the details of the collision. The Impactor spacecraft will also provide close-encounter photos of the comet just prior to impact, giving scientists the most complete view of a comet to date. 

A news briefing was held Friday and there were reports yesterday at the Rocky Mountain News and Boulder Daily Camera. All computer problems are reported to have been fixed, and the mission is compared to firing a pellet at a charcoal briquet six miles away in the dark. The final aiming to hit 9P/Tempel 1 on its sunlit side must be done autonomously by the impactor, 15 light minutes from Earth next July 4th. Following the impact, which may be naked-eye visible from Earth, the flyby spacecraft will have 13 minutes to dump

its most important data to Earth before passing through the comet's tail.

The Deep Impact mission has posted its September newsletter with a brief progress report, a photo of the two spacecraft being stacked together after environmental testing, and an interview with JPL staffer Jennifer Marie Rocca, who is in charge of scenario testing and coordinating launch operations for the mission.

IAU Circulars:  Thirty IAU Circulars from August 5th through September 23rd were made public Friday, including reports of discovery circumstances for comets C/2004 P1 (NEAT), C/2004 Q1 (Tucker), C/2004 Q2 (Machholz), P/2004 R1 (McNaught), C/2004 R2 (ASAS), P/2004 R3 (LINEAR-NEAT), and P/2004 NL_21 (LINEAR), plus some other comet observation details as well as binary asteroid news about Main Belter 854 Frostia and large NEO 2002 CE26.

Risk monitoring - panel 1/1 Major News for 3 Oct. 2004 previous
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Risk monitoring yesterday 3 Oct. tomorrow

The Sunday Daily Orbit Update MPEC carries observations of 2004 RQ252 from yesterday from Hunters Hill and Leura observatories in Australia. These were the first observations reported since September 26th, and today NEODyS and JPL for the second time removed all their impact solutions for this small object.

Summary Risk Table - sources checked at 0351 UTC, 4 Oct




 2004 RQ252JPL 10/3R E M O V E D
NEODyS 10/3R 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.   [ top ]
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