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The Asteroid/Comet Connection's
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Cover: The imagery at left, a stack of 45 eight-second exposures, is from Peter Birtwhistle's confirmation small object 2004 RN251 at Great Shefford Observatory in England last Wednesday evening. He writes: “The set of images was the first I took, centered on the nominal ephemeris position. The object was at the time unconfirmed and moving at 24"/min with an uncertainty area 90'x50' in size. I was already exposing adjacent areas expecting to have a bit of a search to do by the time I managed to spot the 19th mag object towards the edge of frame on the first run! ” See below for more about 2004 RN251, which flew past Earth yesterday at 4.2 lunar distances.

Details: 2004 Sep 15 2024-2039 UT. 45x8s binned 2x2. Main image 22.5'x25', inset enlarged x2. North up. 0.3m f/6.3 Schmidt-Cassegrain + CCD. J95
Small objects – panel 1/2 Major News for 19 Sept. 2004 back top next  

Small objects
Discovery & follow-up for 13-19 September 2004

It was a week with a new Moon, great for discovering small asteroids (“small” is defined at right). Of 22 near-Earth discoveries announced in the last seven days, 12 were small — the most since March (13 in one week). Ten were found by LINEAR in New Mexico, one by the Siding Spring Survey in New South Wales, and one by a Vermont FMO Project volunteer reviewing images online from Spacewatch in Arizona. Another five small asteroids were tracked, one was reported from 1-5 September, and 29 observing facilities participated in the week's work.

A discovery from last week, 2004 RU109, made the closest known passage this week, at 0.957 LD on Monday. 2004 RN251 was at 4.2 lunar distances (LD) yesterday and 2004 SA1 at 9.8 LD on Thursday. Many of this week's discovery announcements were for objects caught after passing their closest point to Earth, including 2004 RG164, which was at 8 LD on September 9th. Nothing close is predicted for the coming week.

Last week's small objects report originally mis-attributed 2004 RC11 observations by Jim Bedient. At least five people have now independently submitted astrometry from New Mexico Skies MPC code H06, all of them so far using Rent-A-Scope remote-controlled instruments. So, unless or until it is known who did certain work, H06 observations in A/CC news will have to be reported as simply coming from “New Mexico Skies.”

<< 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. 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 NEODyS listings for another H calculation, and the Sormano Observatory SAEL (H>22.0, Earth MOID<0.015 AU).
Small objects – panel 2/2 (table) Major News for 19 Sept. 2004 back top next  

Small object observation summary for 13-19 Sept. 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.


Object
Estimated
diameter
JPL
H
MPC
H
Discovery
H in MPEC
Earth
MOID
European Spaceguard Central Node
priority/visibility/campaign
2004 RU109
Apollo
has VIs
17 m/yd26.5126.426.5 2004-R630.001226 AU
2004 RU109 was reported this past week as observed on 12 Sept. by LINEAR, 7300 Obs., and finally by Starkenburg Obs. before it went out of view. It has an MOID of 0.013 AU with Mars. See last week's report about this object, which briefly intruded into the Earth-Moon system on 13 Sept..
2004 SA
Amor
20 m/yd26.1226.126.1 2004-S110.040157 AU
NEW: With 2004 SA, Lawrence Garrett became the first FMO Project online volunteer to make two discoveries that have received IAU designations. He found it 16 Sept. in images from the Spacewatch 0.9m telescope, the day that it came to 15.6 lunar distances (LD) from Earth. It was confirmed on 16 Sept. by KLENOT, and on 17 Sept. by Powell, Three Buttes, Table Mountain, and Sabino Canyon observatories and with the Spacewatch 1.8m telescope, and it was announced in MPEC 2004-S11 of 17 Sept. This object was also observed on 17 Sept. by Mt. John Obs.
2004 RN251
Apollo
23 m/yd25.8626.026.0 2004-R890.004615 AU
NEW: 2004 RN251 was discovered the morning of 15 Sept. by LINEAR and was confirmed that night by Great Shefford Obs. (see “cover” image above). With LINEAR observations covering 68 minutes and Great Shefford's 44 minutes — nine positions total over an observing arc of 14.345 hours, this object was announced the same day UT in MPEC 2004-R89. It was also observed on 16 Sept. by Great Shefford Obs., LINEAR, and Powell Obs. and on 17 Sept. by Farpoint Obs. It has an MOID of 0.021 AU with Mars, and flew past Earth on 18 Sept. at 4.2 LD.
2004 RG164
Apollo
26 m/yd25.5825.825.1 2004-R750.006475 AUUseful, visibility ends 16 Oct.
NEW: 2004 RG164 passed the Earth at 8 LD on Sept. 9th and was discovered early the next day by LINEAR, which also observed it on 11 and 12 Sept. in three sessions covering 1.069, 0.804, and 1.869 hours respectively, but it apparently was posted to the NEOCP only briefly on the 14th, when KLENOT confirmed it and RG164 was announced in MPEC 2004-R75 that day. This object was also observed on 14 Sept. by Farpoint Obs. and LINEAR, on 15 Sept. by Great Shefford Obs., on 16 Sept. with the Spacewatch 0.9m telescope and Consell Obs., and on 18 Sept. by KLENOT and Pla D'Arguines Obs. It has an MOID of 0.007 AU with Mars.
2004 SA1
Apollo
34 m/yd25.0225.025.0 2004-S200.02125 AU
NEW: 2004 SA1 passed the Earth at 9.8 LD on 16 Sept. and was discovered the next day by LINEAR, which confirmed it on the 18th along with Great Shefford Obs. and KLENOT, and it was announced in MPEC 2004-S20 that day. It was also observed 18 Sept. by Sormano Obs. and 19 Sept. by Great Shefford Obs.
2004 RN111
Apollo
39 m/yd24.6725.025.2 2004-R730.034412 AUNecessary, visibility ends 3 Oct.
NEW: 2004 RN111 passed the Earth at 14.8 LD on 9 Sept. and was discovered on the 12th by LINEAR. It was confirmed on 13 Sept. by Powell Obs. and Farpoint Obs., and was announced in MPEC 2004-R73 that day. This object was also observed on 13 Sept. by LINEAR and Great Shefford Obs., on 16 Sept. by KLENOT, and on 17 Sept. by KLENOT.
2004 RW2
Apollo
46 m/yd24.3424.524.5 2004-R300.037725 AUNecessary, visibility ends 21 Sept.
It was reported this week that 2004 RW2 was observed on 8 Sept., and also on the 17th, by Powell Obs.
2004 RC80
Amor
47 m/yd24.2724.324.6 2004-R510.043643 AUUseful, visibility ends 6 Oct.
2004 RC80 was observed on 13 Sept. by LINEAR, Great Shefford Obs., and KLENOT, on 14 Sept. by Farpoint Obs., and on 17 and 18 Sept. by KLENOT.
2004 RV164
Apollo
49 m/yd24.1824.324.4 2004-R800.000787 AUNecessary, visibility ends 20 Oct.
NEW: 2004 RV164 passed the Earth at 11.2 LD on 8 Sept. and was discovered on the 13th by LINEAR. It was confirmed on 14 Sept. by Great Shefford, Farpoint, Three Buttes, Grasslands, and Table Mountain observatories, and by Robert Hutsebaut using a Rent-A-Scope telescope (see cover image). And it was announced in MPEC 2004-R80 of 14 Sept. This object was also observed on 14-17 Sept. by LINEAR, on 14 Sept. by Great Shefford Obs., on 16 and 17 Sept. by Consell Obs., on 16 Sept. by KLENOT and Powell Obs., and on 18 Sept. by Begues Obs. and KLENOT. Robert Hutsebaut observed it again on the 15th and noted to A/CC: “On the 14 Sept. confirmation this object was an easy target but in the 15 Sept. observations it was very difficult for the 0.25m! (Same number of images with the same exposure with about the same sky conditions.)” 2004 RV164 was briefly listed by JPL this week with impact solutions.
2004 ST2
Aten
53 m/yd24.0224.124.1 2004-S230.046463 AU
NEW: 2004 ST2 was discovered on 18 Sept. by LINEAR, the day after it came to 26.1 LD from Earth. It was confirmed on 18 Sept. by KLENOT and Great Shefford Obs., and on 19 Sept. by Great Shefford Obs., and was announced in MPEC 2004-S23 of 19 Sept.
2004 SR
Apollo
59 m/yd23.8023.723.7 2004-S140.025376 AU
NEW: 2004 SR passed Earth at 10.8 LD on 10 Sept., was discovered by LINEAR on the 17th, and was linked to LONEOS observations from the 14th. It was confirmed 17 Sept. by Tentlingen Obs. and 18 Sept. by KLENOT, and was announced in MPEC 2004-S14 of 18 Sept. This object was also observed on 18 Sept. by LINEAR, Francisquito Obs., Eschenberg Obs., and Sormano Obs.
2004 RC11
Apollo
70 m/yd23.4123.523.6 2004-R460.004998 AUNecessary, visibility ends 23 Oct.
2004 RC11 was observed on 16 Sept. by KLENOT, adding 5.918 days to what had been a 2.761-day observing arc. This object has an MOID of 0.023 AU with Mars.
2004 RB11
Amor
74 m/yd23.3023.724.0 2004-R450.036569 AUUseful, visibility ends 21 Nov.
2004 RB11 was observed on 10 Sept. by LINEAR and on 15 Sept. by Great Shefford Obs.
2004 RO111
Aten
84 m/yd23.0323.323.6 2004-R740.02383 AUNecessary, visibility ends 4 Oct.
NEW: 2004 RO111 was discovered on 12 Sept. by LINEAR, was confirmed on 13 Sept. by Farpoint, Table Mountain, Powell, and Sabino Canyon observatories, and was announced in MPEC 2004-R74 of 13 Sept. This object was also observed on 16 Sept. by LINEAR, on 17 Sept. by LINEAR, KLENOT, and Consell Obs., and on 18 Sept. by KLENOT. It has an MOID of 0.035 AU with Venus, and will pass 28.3 LD from the Earth on Sept. 29th.
2004 QF14
Apollo
99 m/yd22.6622.924.2 2004-Q460.017956 AUUseful, visibility ends 8 Oct.
2004 QF14 was reported this past week as observed on 1 Sept. with Faulkes Telescope North, and was also observed on 17 Sept. by KLENOT.
2004 RL251
Amor
107 m/yd22.5122.622.5 2004-R870.035711 AUUseful, visibility ends 15 Nov.
NEW: 2004 RL251 was discovered on 14 Sept. by LINEAR, the day after it came to 23.2 LD from Earth. It was confirmed on 15 Sept. by LINEAR and Great Shefford Obs., and was announced in MPEC 2004-R87 of 15 Sept. This object was also observed on 16 Sept. by KLENOT, Consell Obs., Begues Obs., LINEAR, and Stony Ridge Obs., on 17 Sept. by KLENOT and Consell Obs., and on 18 Sept. by Cascade Mountain, Eschenberg, Pla D'Arguines, Great Shefford, and Sormano observatories. It has an MOID of 0.008 AU with Mars.
2004 QA2
Amor
114 m/yd22.3722.422.1 2004-Q210.030088 AUNecessary, visibility ends 6 Oct.
2004 QA2 was reported this past week as observed on 1 and 5 Sept. with the Australian Natl. Univ. (ANU) 1m telescope.
2004 RQ252
Apollo
has VIs
115 m/yd22.3422.322.3 2004-S050.000415 AUUrgent, visibility ends 12 Oct.
NEW: 2004 RQ252 was discovered on 15 Sept. by the Southern Sky Survey (SSS), was confirmed on 16 Sept. by Powell, Three Buttes, Table Mountain, and Sabino Canyon observatories, and finally by SSS itself in three sessions spanning 8.47 hours. It was announced in MPEC 2004-S05 of 16 Sept. This object was also observed on 17 Sept. by Mt. John Obs. and on 18 Sept. by SSS. It has an MOID of 0.045 AU with Venus, and will be at 21.3 LD from Earth on Oct. 9th.
2004 SS
Amor
135 m/yd22.0022.122.1 2004-S150.033308 AU
NEW: 2004 SS came to 19.1 LD from Earth on Sept. 8th. It was discovered on the 17th by LINEAR and linked to LONEOS observations from the 14th (as with 2004 SR above). It was confirmed 17 Sept. by La Canada Obs. and on 18 Sept. by Eschenberg Obs., KLENOT, Pla D'Arguines Obs., and Modra Obs., and was announced in MPEC 2004-S15 of 18 Sept. This object was also observed on 18 Sept. by LINEAR, Francisquito Obs., and Robert Hutsebaut, and on 19 Sept. by Great Shefford Obs.
2004 RE84
Apollo
145 m/yd21.8422.122.6 2004-R550.019881 AUUrgent, visibility ends 10 Oct.
2004 RE84 was observed on 12 Sept. by LINEAR and with the Spacewatch 0.9m telescope, on 13 Sept. by LINEAR and KLENOT, on 14 Sept. by Farpoint Obs., on 17 Sept. by KLENOT and Eschenberg Obs., and on 18 Sept. by LINEAR. It has an MOID of 0.029 AU with Venus.

  Small object observation cross index   [table top]
ObjectObserved by MPC code
2004 QA2413
2004 QF14246 & F65
2004 RB11704 & J95
2004 RC11246
2004 RC80246, 704, 734 & J95
2004 RE84151, 246, 691, 704 & 734
2004 RG164176, 246, 691, 704, 734, 941 & J95
2004 RL251151, 170, 176, 246, 587, 671, 704, 941, H44 & J95
2004 RN111246, 649, 704, 734 & J95
2004 RN251649, 704, 734 & J95
2004 RO111176, 246, 649, 673, 704, 734 & 854
2004 RQ252474, 649, 673, 854, E12 & G90
2004 RU109611, 704 & H07
2004 RV164170, 176, 246, 649, 651, 673, 704, 734, G90, H06 & J95
2004 RW2649
2004 SA246, 291, 474, 649, 673, 691, 854 & G90
2004 SA1246, 587, 704 & J95
2004 SR151, 246, 587, 699, 704, A16 & G70
2004 SS118, 151, 246, 699, 704, 941, G70, H06, J87 & J95
2004 ST2246, 704 & J95
CodeObservatoryObjects observed (days)
118Modra Obs.2004 SS
151Eschenberg Obs.2004 RE84, 2004 RL251, 2004 SR & 2004 SS
170Begues Obs.2004 RL251 & 2004 RV164
176Consell Obs.2004 RG164, 2004 RL251(2), 2004 RO111 & 2004 RV164(2)
246KLENOT2004 QF14, 2004 RC11, 2004 RC80(3), 2004 RE84(2), 2004 RG164(2), 2004 RL251(2), 2004 RN111(2), 2004 RO111(2), 2004 RV164(2), 2004 SA, 2004 SA1, 2004 SR, 2004 SS & 2004 ST2
291Spacewatch 1.8m telescope2004 SA
413Australian Natl. Univ. 1m telescope2004 QA2(2)
474Mt. John Obs.2004 RQ252 & 2004 SA
587Sormano Obs.2004 RL251, 2004 SA1 & 2004 SR
611Starkenburg Obs.2004 RU109
649Powell Obs.2004 RN111, 2004 RN251, 2004 RO111, 2004 RQ252, 2004 RV164, 2004 RW2(2) & 2004 SA
651Grasslands Obs.2004 RV164
671Stony Ridge Obs.2004 RL251
673Table Mountain Obs.2004 RO111, 2004 RQ252, 2004 RV164 & 2004 SA
691Spacewatch 0.9m telescope2004 RE84, 2004 RG164 & 2004 SA
699LONEOS2004 SR & 2004 SS
704LINEAR2004 RB11, 2004 RC80, 2004 RE84(3), 2004 RG164(2), 2004 RL251(3), 2004 RN111, 2004 RN251(2), 2004 RO111(2), 2004 RU109, 2004 RV164(5), 2004 SA1(2), 2004 SR(2), 2004 SS(2) & 2004 ST2
734Farpoint Obs.2004 RC80, 2004 RE84, 2004 RG164, 2004 RN111, 2004 RN251, 2004 RO111 & 2004 RV164
854Sabino Canyon Obs.2004 RO111, 2004 RQ252 & 2004 SA
941Pla D'Arguines Obs.2004 RG164, 2004 RL251 & 2004 SS
A16Tentlingen Obs.2004 SR
E12Southern Sky Survey (SSS)2004 RQ252(2)
F65Faulkes Telescope North2004 QF14
G70Francisquito Obs.2004 SR & 2004 SS
G90Three Buttes Obs.2004 RQ252, 2004 RV164 & 2004 SA
H06New Mexico Skies
 – Robert Hutsebaut
2004 RV164(2) & 2004 SS
H077300 Obs.2004 RU109
H44Cascade Mountain Obs.2004 RL251
J87La Canada Obs.2004 SS
J95Great Shefford Obs.2004 RB11, 2004 RC80, 2004 RG164, 2004 RL251(2), 2004 RN111, 2004 RN251(2), 2004 RV164(2), 2004 SA1(2), 2004 SS & 2004 ST2(2)
Precovery, recovery & comet news – panel 1/1 Major News for 19 Sept. 2004 previous
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Precovery, recovery & comet news

MPEC 2004-S17, issued with a 1638 UT time stamp yesterday, showed that an asteroidal object, which LINEAR in New Mexico found in July wandering around the Main Belt and was observed up through yesterday, had been caught exhibiting cometary activity. Not quite two and a half hours later, MPEC 2004-S18 reported precovery positions for this comet, now designated P/2004 NL21 (LINEAR). These were found by Maik Meyer in 8 and 15 September 1996 images from NEAT's telescope on Haleakala in Hawaii.

The next MPEC issued yesterday, 2004-S19, carried archive precovery work from “R. Haver, A. Pelloni, G. Forti, M. Read,” who had located 2004 DA62 in scans of plates from 12 March and 17 April 1983 from the U.K. Schmidt 1.2m telescope at Siding Spring in Australia. Discovered by LINEAR on February 25th and observed up through July 21st, this object travels a highly inclined (i=52.2°) path that takes it through the ecliptic inside Jupiter's orbit and outside Saturn's. From its brightness, it is estimated to be on the order of 9.3 km. (5.8 miles) wide, and maybe larger.

Three MPECs, and less than six hours, later, MPEC 2004-S22 early today reported the recovery and precovery of Edgeworth-Kuiper Belt object 2003 UZ117. It was caught

early yesterday by Erich Meyer at Linz Observatory in Austria and last night on both sides of midnight at KLENOT in the Czech Republic. And Reiner Stoss is reported to have found it in 13 November 2002 NEAT images from its Mt. Palomar telescope. This object, which was discovered 24 October 2003 with the Spacewatch 0.9m telescope in Arizona, had been last reported seen on 22 November, and is estimated very roughly from its brightness to be about 385 km. (240 miles) wide.

And the large PHO 2003 QO104, which hadn't been reported since 22 December 2003, was in Friday's Daily Orbit Update MPEC (DOU) as having been picked up Thursday morning with the Spacewatch 1.8m telescope. Estimated at 2.3 km. (1.4 miles) wide, this object gave NEO observers quite a chase after its 31 August 2003 discovery with NEAT's telescope on Haleakala and announcement on September 2nd. It was listed at Torino Scale 1 for much of the time until its last impact solutions were removed on October 13th. Later that month, in the DOU of the 31st, a set of archival positions were reported from 20 December 2001 from NEAT/Palomar.

Risk monitoring - panel 1/1 Major News for 19 Sept. 2004 previous
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Risk monitoring 19 Sept.

The Sunday Daily Orbit Update MPEC has observation of 2004 RQ252 from yesterday from its discoverer, the Siding Spring Survey (SSS) in Australia. Today NEODyS cut its risk assessment to just one low-rated impact solution in 2012, and JPL solidly lowered its its overall risk ratings for this small object.

Summary Risk Table - sources checked at 0408 UTC, 20 Sep

Object

Assessment

Years

VI
PS
cum
PS
max
T
S
Arc 
days
 2004 RU109 NEODyS 9/142038-20536-6.72-7.1301.627
JPL 9/142038-20535-6.81-7.2101.627
 2004 RQ252 NEODyS 9/192012-20121-5.32-5.3203.051
JPL 9/192012-20194-4.92-4.9503.051
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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