Sunday29 February 20041:20pm MST2004-02-29 UTC 2020 back top next  

The Asteroid/Comet Connection's
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asteroids, comets, and meteors


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Cover: Seen at 200%, this stack of 35 24-second exposures from late Friday has a gap of ten frames (note that each background star appears as two streaks), says Peter Birtwhistle, to separate 2004 DA53 from a bright star and a very fast moving object "(probably an artificial satellite) that passed within a few arcseconds." And the "curved line at top right is a reflection of a very bright star just off frame at lower left." 2004 DA53 is roughly estimated at just under ten meters wide (more info yesterday and below).

Details: 35x24-sec. exposures stacked, taken 2004 Feb 27 2258-2328 UT binned 2x2 with 0.3m Schmidt-Cassegrain from Great Shefford, the measured magnitude was +20.6R.
Small objects – part 1/2 Major News for 29 Feb. 2004 back top next  
Small objects  

Discovery & follow-up 23-29 February

During this past week, one new-found object was announced with absolute magnitude (brightness) calculated at H greater than 22.0, which converts to roughly 135 meters/yards wide or less. Four other such objects were tracked, and two more were reported with observations from before the week.

Discovery:  As reported yesterday, 2004 DA53 (H=28.0) was discovered by LINEAR early Thursday. Peter Birtwhistle, who has today's "cover" above, tells A/CC: Powell Observatory got the [first] confirmation on this. I got images on the first night while it was still unconfirmed and covered the whole uncertainty area, which by then was three overlapping fields for my system. It was moving at 12.7"/min. and already fairly faint. On that night I didn't locate it (it was actually just outside the uncertaintly area), and only found it later that morning when I saw Powell's note on the NEOCP that it was 8' NE of the original ephemeris.

Flybys:  On February 24th, according to the Sormano Observatory Small Asteroids list (SAEL), 2004 CZ (H=24.31) came within 6.2 lunar distances (LD) of Earth, which was predicted, and also the then unknown 2004 DA53 flew past at less than 1.3 LD. Next week, on March 5th, 2004 CE39 (H=21.37) will fly past at 33.6 LD.

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

If an asteroid's orbit brings it to within 0.05 AU of Earth's orbit, it is categorized as "potentialy 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 is dimmer, thus smaller. And 0.05 astronomical units (AU) is about 19.5 times the distance between Earth and Moon (0.00256 AU).

Notes: Diameters in the observation summary table are from a standard but very inexact H-to-size formula using H (absolute magnitude) from the JPL NEO Orbital Elements page, source also for Earth MOID (minimum orbital intersection). Other planetary MOIDs are from Lowell Observatory. Current Minor Planet Center H is also given, along with H from each object's discovery MPEC. Priorities and visibilities are from the European Spaceguard Central Node (SCN). Exception: The JPL Horizons and NEO data pages haven't updated since 2004 DA53 was announced, so MPC H and Lowell MOID are used.

Small objects – part 2/2 (table) Major News for 29 Feb. 2004 back top next  

Small object observation summary for 23-29 February

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 DA53
Aten
9 m/yd28.028.0 2004-D460.00291 AU (LO)Urgent, visibility ends 3 March
NEW: 2004 DA53 was discovered on 26 Feb. by LINEAR, was confirmed on 27 Feb. by Powell Obs. and later by Great Shefford Obs. with observations from 26 and 27 Feb., and was announced in MPEC 2004-D46 of 28 Feb. See image and reports yesterday and above. It has an MOID of 0.007 AU with Venus, and passed Earth at less than 1.3 lunar distances on 24 Feb. (20th in the top-20 known closest).
2004 CQ
Amor
37 m/yd24.8024.724.6 2004-C390.04005 AUNecessary, visibility ends 16 March
2004 CQ was observed on 26 Feb. by Powell Obs.
2004 CZ1
Apollo
47 m/yd24.3124.424.4 2004-C490.00408 AU
2004 CZ1 was observed on 22 and 23 Feb. by Great Shefford Obs., and on 24 Feb. by Tenagra II Obs. and Camarillo Obs. It came within 6.2 lunar distances of Earth on 24 Feb.
2004 BF11
Amor
52 m/yd24.0524.024.2 2004-B150.14201 AU
2004 BF11 was observed 22 Feb. with the Spacewatch 1.8m telescope. It has a Mars MOID of 0.047 AU.
2003 QY29
Amor
134 m/yd22.0222.322.7 2003-Q260.07120 AU
2003 QY29 was reported this last week from David Tholen's University of Hawaii team at Mauna Kea as observed on 29 Aug. 2003, within the existing observing arc.
2004 BT58
Aten
142 m/yd21.8922.022.1 2004-B440.07855 AU
2004 BT58 was reported this last week as observed on 14 Feb. by Jornada Obs.
2004 CE39
Apollo
180 m/yd21.3721.622.4 2004-C600.07688 AUNecessary, visibility ends 22 March
2004 CE39 was observed on 23 Feb. by LINEAR, on 25 Feb. by Stonegate Obs. and Modra Obs., on 26 Feb. by Hobbs Obs., Herrenberg Obs., and Linhaceira Obs., and on 28 Feb. by Camarillo Obs. and Begues Obs. It has an MOID of 0.014 AU with Venus, and will pass Earth at 33.6 lunar distances on 5 March.

  Small object observation cross index   [table top]
ObjectObserved by MPC code
2003 QY29568
2004 BF11291
2004 BT58715
2004 CE39118, 170, 240, 670, 704, 750, 938 & H67
2004 CQ649
2004 CZ1670, 926 & J95
2004 DA53649, 704 & J95
CodeObservatoryObjects observed (days)
118Modra Obs.2004 CE39
170Begues Obs.2004 CE39
240Herrenberg Obs.2004 CE39
291Spacewatch 1.8m telescope2004 BF11
568Mauna Kea2003 QY29
649Powell Obs.2004 CQ & 2004 DA53
670Camarillo Obs.2004 CE39 & 2004 CZ1
704LINEAR2004 CE39 & 2004 DA53
715Jornada Obs.2004 BT58
750Hobbs Obs.2004 CE39
926Tenagra II Obs.2004 CZ1
938Linhaceira Obs.2004 CE39
H67Stonegate Obs.2004 CE39
J95Great Shefford Obs.2004 CZ1(2) & 2004 DA53(2)
Risk monitoring - part 1/1 Major News for 29 Feb. 2004 back top next  
Risk monitoring 29 Feb.

The Sunday Daily Orbit Update MPEC has observations of 2004 DV24 from Tentlingen Observatory late on February 27th and from Consell Observatory last night.

As of 11:30am on a Sunday in Pasadena, JPL has not yet updated its risk assessments with yesterday's new 2004 DM44 data nor on two days of new 2004 DV24 data. Other JPL NEO and Solar System Dynamics pages also appear not to have been updated since Friday, including Horizons (orbital elements).

Update:  NEODyS has issued a new 2004 DV24 assessment that very slightly raises its overall risk ratings.

Summary Risk Table - sources checked at 2358 UTC, 29 Feb

Object

Assessment

Years

VI
PS
cum
PS
max
T
S
Arc 
days
 2004 DV24 NEODyS 2/292023-20779-1.84-1.9907.499
JPL 2/262023-210121-1.89-2.3804.506
 2004 DM44NEODyS 2/28R E M O V E D
JPL 2/272057-20967-5.49-5.9001.125
 2004 DC NEODyS 2/262013-207426-2.72-3.3508.973
JPL 2/262029-210129-2.22-3.0108.973
 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.

Note: This will be the last day that A/CC shows the lost object 2004 BG121 in the Summary Risk Table (at right) and on the Consolidated Risk Tables (CRT) page. These show only objects listed with impact solutions that are active observation and analysis, and 2004 BG121 hasn't been reported seen since it was announced on February 11th with a 23-hour discovery arc that ended January 31st (later observations in the discovery MPEC were subsequently unlinked).

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