Sunday1 August 20045:06pm MDT2004-08-01 UTC 2306 back top next  

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

Today's issue status: done


Cover: Earth co-orbital 54509 2000 PH5 [link|alt] observed last Monday morning (July 26th) by Pepe Manteca at Begues Observatory in Spain (north is up and east left). See the A/CC cover that day for more info and his imagery of this small object from a year ago, and see below for this week's observing record.

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

Small objects
Discovery & follow-up for 26 July – 1 August

With nights still short in the northern hemisphere, where most NEO observing is done, and with the Moon interfering as it brightened to full yesterday, there is little to report this past week for observation of small asteroids (defined at right). One discovery was announced on July 27th, and two other objects were followed, including the only numbered small asteroid. Fourteen observatories participated in the week's work.

The discovery came from Michael Van Ness at LONEOS in Arizona thirteen days after 2004 OW10 passed Earth at 4.6 lunar distances (LD). No close passes are predicted for August.

In last week's report, some older observations credited to MPC code J50 for “La Palma-NEON” were described as coming from the Network of European Observatories in the North (NEON) Archive Observing School. That was an error. A/CC has learned that the J50 code is assigned to the Nordic Near-Earth-Object Network of Spaceguard (NEON) which has a current run on the 2.5m Nordic Optical Telescope (NOT). Its observations previously had been coded with MPC#950, which is used generically for a variety of users of several La Palma telescopes.

<< 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 1 Aug. 2004 back top next  

Small object observation summary for 26 July – 1 Aug.

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 OW10
43 m/yd24.5024.524.4 2004-O390.00447 AUUrgent, visibility ends 27 Aug.
NEW: 2004 OW10 flew past Earth at 4.6 lunar distances on July 12th and was discovered on July 25th by Michael Van Ness at LONEOS, was confirmed on 26 and 27 July by Sandlot Obs., and on 27 July by Mt. John Obs., and Table Mountain Obs., and was announced in MPEC 2004-O39 of 27 July. This object was also observed on 27 July by Wykrota Obs. and Mt. John Obs. It has an MOID of 0.008 AU with Mars.
2004 HB39
100 m/yd22.6522.722.5 2004-H740.093466 AUUseful, visibility ends 17 Aug.
2004 HB39 was observed on 24 and 25 July by the Nordic Near-Earth-Object Network of Spaceguard (NEON) with the 2.5m Nordic Optical Telescope (NOT).
2000 PH5

107 m/yd22.5122.721.9 2000-P320.001726 AU
54509 2000 PH5 was observed on 26 July by Camarillo Obs., Begues Obs. (see cover above), and McCarthy Obs., on 28 July by Powell Obs., Dresden Obs., and Jurassien-Vicques Obs., on 29 July by Herrenberg Obs., and on 31 July by Powell Obs. and Modra Obs. This object shares Earth's orbit and came within 5 LD of Earth on July 25th. See the July 26th cover for more info and links. Catchall Catalog entry (alternate).

  Small object observation cross index   [table top]
ObjectObserved by MPC code
2004 HB39J50
2004 OW10474, 673, 699, 859 & H36
54509 2000 PH5118, 170, 185, 240, 639, 649, 670 & 932
CodeObservatoryObjects observed (days)
118Modra Obs.54509 2000 PH5
170Begues Obs.54509 2000 PH5
185Jurassien-Vicques Obs.54509 2000 PH5
240Herrenberg Obs.54509 2000 PH5
474Mt. John Obs.2004 OW10(2)
639Dresden Obs.54509 2000 PH5
649Powell Obs.54509 2000 PH5(2)
670Camarillo Obs.54509 2000 PH5
673Table Mountain Obs.2004 OW10
699LONEOS2004 OW10
859Wykrota Obs.2004 OW10
932McCarthy Obs.54509 2000 PH5
H36Sandlot Obs.2004 OW10(2)
J50NEON/Nordic Optical Telescope (NOT)2004 HB39(2)
Risk monitoring - panel 1/1 Major News for 1 August 2004 back top next  
Risk monitoring 1 August

The Sunday Daily Orbit Update MPEC (DOU) has observation of 2004 OT11 from yesterday morning from Powell Observatory in Kansas and this morning from Pla D'Arguines Observatory in Spain and Great Shefford Observatory in England. Today NEODyS very slightly, and JPL slightly, lowered risk ratings for this kilometer-size object while both cut their impact solution counts by about two thirds.

Today's DOU also has observation of 2004 NL8 from Powell yesterday morning and Pla D'Arguines this morning. Today NEODyS cut back to one impact solution and sharply lowered its risk assessment for this kilometer-size object.

Summary Risk Table - sources checked at 2109 UTC, 1 Aug




 2004 OT11 NEODyS 8/12008-20756-2.66-2.7204.677
JPL 8/12008-209811-2.65-2.7204.677
 2004 NL8 NEODyS 8/12073-20731-6.70-6.70020.699
JPL 7/28R E M O V E D
 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.   [ top ]
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