Sunday18 July 20045:44pm MDT2004-07-18 UTC 2344 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: One of this past week's three small object discoveries, 2004 NU7 is seen in this confirmation imagery from a 0.3m f/9 Schmidt-Cassegrain telescope at Observatorio Astronomico de Mallorca (OAM) from late on July 15th, observers Observers Salvador Sanchez, Reiner Stoss, and Jaime Nomen. This is a composite of two stacks centered on 2004 NU7, which was moving 3.46"/min. in P.A. 98.6° and was measured at magnitude V=19.9. Each stack consists of nine 60-second exposures. Beside NU7, the full frame also includes two Main Belt asteroids seen as trails at angles differing from the star trails. At lower right is 17590 1995 CG and inset, from off the cropped frame to the left, is 14966 Jurijvega.

Small objects – panel 1/2 Major News for 18 July 2004 back top next  

Small objects
Discovery & follow-up for 12-18 July

This past week the Minor Planet Center's NEO Confirmation Page (NEOCP) came alive again with many targets to chase. Three of those, including July's first near-Earth object discovery, were small asteroids (defined at right) discovered by LINEAR in New Mexico. Another three small ones were tracked, and one more was reported observed back in June. Eight observatories participated in the week's work.

There were no known small object close flybys last week, but we did learn that there were two unknown flybys the previous week, on July 9th and 10th at 23.2 and 22.0 lunar distances (LD), by 2004 NF3 and 2004 NK8 respectively. And there is one known close flyby coming this next week, on Sunday, when the only numbered small object, Earth co-orbital candidate 54509 2000 PH5 [link|alt], will pass by at 5 LD.

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

Note: It turned out that last week's lack of a Sunday Daily Orbit Update MPEC possibly affected the small object observation summary in regard only to a July 10th observation of 2004 LK.

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 18 July 2004 back top next  

Small object observation summary for 12-18 July

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 MO4
Amor
32 m/yd25.1324.924.6 2004-M450.023258 AUNecessary, visibility ends 3 Aug.
2004 MO4 was observed on 11 July by LINEAR, on 12 July with the Australian Natl. Univ. (ANU) Obs. 1m telescope, and on 15 July by Powell Obs. It has an MOID of 0.027 AU with Mars.
2004 NF3
Amor
45 m/yd24.3724.624.5 2004-N400.057776 AUUseful, visibility ends 31 Aug.
NEW: 2004 NF3 was discovered on 11 July by LINEAR, was confirmed on 13 July by Powell Obs. and Mt. John Obs., and was announced in MPEC 2004-N40 of 13 July, the first near-Earth asteroid of any size to be discovered in July (see news). This object was also observed on 14 July by LINEAR, on 15 July by Powell Obs., and on 16 July by KLENOT. It has an MOID of 0.046 AU with Mars, and flew past Earth at 23.2 lunar distances (LD) on July 9th.
2004 NU7
Amor
62 m/yd23.6824.524.6 2004-O010.01381 AU
NEW: 2004 NU7 was discovered on 14 July by LINEAR, was confirmed on 15 July by LINEAR and Obs. Astronomico de Mallorca (OAM, see “cover” above), and was announced in MPEC 2004-O01 of 16 July. This object was also observed on 17 July by LINEAR. It has an MOID of 0.027 AU with Mars.
2004 MC
Apollo
79 m/yd23.1523.323.3 2004-M070.007485 AUNecessary, visibility ends 27 July
2004 MC was reported this past week as observed on 27 June by Brooklyn Park Obs. It has an MOID of 0.031 AU with Mars.
2004 NK8
Apollo
84 m/yd23.0223.023.1 2004-O060.036056 AU
NEW: 2004 NK8 was discovered on 15 July by LINEAR, was confirmed on 16 July by LINEAR and KLENOT, and was announced in MPEC 2004-O06 of 16 July. This object was also observed on 17 July by Mt. John Obs. 2004 NK8 flew past Earth at 22.0 LD on July 10th.
2004 LK
Amor
99 m/yd22.6722.722.7 2004-L220.068733 AUUseful, visibility ends 10 Oct.
2004 LK was observed on 10 July by Mt. John Obs. and on 12 July with the ANU 1m telescope.
2004 MO3
Apollo
120 m/yd22.2622.422.3 2004-M390.01127 AUUseful, visibility ends 19 Aug.
2004 MO3 was observed on 12 July by Sormano Obs. and on 13 July by Table Mountain Obs. It has an MOID of 0.024 AU with Mars.

  Small object observation cross index   [table top]
ObjectObserved by MPC code
2004 LK413 & 474
2004 MCD87
2004 MO3587 & 673
2004 MO4413, 649 & 704
2004 NF3246, 474, 649 & 704
2004 NK8246, 474 & 704
2004 NU7620 & 704
CodeObservatoryObjects observed (days)
246KLENOT2004 NF3 & 2004 NK8
413Australian Natl. Univ. 1m telescope2004 LK & 2004 MO4
474Mt. John Obs.2004 LK, 2004 NF3 & 2004 NK8
587Sormano Obs.2004 MO3
620Obs. Astronomico de Mallorca2004 NU7
649Powell Obs.2004 MO4 & 2004 NF3(2)
673Table Mountain Obs.2004 MO3
704LINEAR2004 MO4, 2004 NF3(2), 2004 NK8(2) & 2004 NU7(3)
D87Brooklyn Park Obs.2004 MC
Risk monitoring - panel 1/1 Major News for 18 July 2004 back top next  
Risk monitoring 18 July

The Sunday Daily Orbit Update MPEC has observation of 2004 NL8 from yesterday morning from LINEAR in New Mexico. And today the two risk monitors very slightly changed their risk assessments for this mile-size object, with the NEODyS risk ratings down for a period ending in 2080 and JPL's up for the period through 2104. NEODyS cut its impact solution count by more than half, and JPL cut its by a third, and both removed all solutions before 2020.

Summary Risk Table - sources checked at 2159 UTC, 18 Jul

Object

Assessment

Years

VI
PS
cum
PS
max
T
S
Arc 
days
 2004 NL8 NEODyS 7/182020-207740-2.77-3.4206.078
JPL 7/182020-210445-2.72-3.4206.078
 2004 MP7JPL 7/152087-20871-3.86-3.86017.192
NEODyS 7/1R E M O V E D
 2004 MO7 NEODyS 6/302012-208067-4.34-5.2003.869
JPL 6/302016-208811-4.83-5.4803.869
 2004 ME6JPL 6/282017-209943-5.64-6.3500.873
 NEODyS 6/272044-20637-7.29-7.7600.873
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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