Saturday17 April 200411:40pm MDT2004-04-18 UTC 0540 back top next  

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


Today's issue status: done
yesterdayApriltomorrowIndex

Cover: Discovered by LONEOS in Arizona yesterday morning, small object 2004 HE was confirmed overnight from several facilities including New Mexico Skies, where Robert Hutsebaut in Belgium was remotely operating a telescope. The image at left corresponds to the position he reported from 0922 UT this morning. 2004 HE will be at 0.74 lunar distance in the next 24 hours. In this stack of eight ten-second exposures centered on the object's fast motion, the stars behind it appear as strings of beads. See more info below.

Intruder 2004 HE – panel 1/2 Major News for 17 April 2004 back top next  
Intruder 2004 HE

The Minor Planet Center Closest Approaches page now shows an average of one asteroid per month observed to come closer to the Earth than the Moon in the last seven months, since September 19th. There have been eight since 29 April 2003, out of a total of 15 ever observed so close, going back to the first in 1991.

With the current prediction of 0.0019 AU (0.74 lunar distance), 2004 HE is on the list as the 13th closest flyby overall, and only seventh closest in the last year. It was discovered at 0758 and followed until 0853 UT yesterday by Michael Van Ness at LONEOS in Arizona, and was confirmed as night wrapped around the world, first by Rob McNaught during 1157-1433 UT with the Siding Spring Survey (SSS) 0.5m telescope in Australia, and then at 2304 UT by Michal Kocer with the KLENOT 1.06m telescope in the Czech Republic. Now early on the 17th back in the U.S. Southwest, it was picked up with a rented 0.3m telescope (see "cover" above) at New Mexico Skies operated by Robert Hutsebaut in Belgium (where it was mid-morning).

Animation of 2004 HE's Earth-Moon passage 
by Pasquale Tricarico using ORSA
Animation by Pasquale Tricarico using ORSA for Linux and Windows. The drop line from the object shows how it climbs through the Earth-Moon system.

And, finally, back once more to the South Pacific, where Alan Gilmore and Pam Kilmartin with a 0.6m telescope at Mt. John Observatory in New Zealand, and then SSS again in Australia, closed out the confirmation process, ending at 1208 UT and resulting 42 minutes later in today's MPEC 2004-H16 announcement.

At absolute magnitude H=26.7 (JPL says 26.75), the standard conversion formula puts the diameter for 2004 HE at roughly 15 meters/yards. So, if it ever

more about 2004 HE >>

Intruder 2004 HE – panel 2/2 Major News for 17 April 2004 back top next  

<< continued from panel 1

did hit Earth, it would most likely self-destruct spectacularly high in the atmosphere.

Pasquale Tricarico used his ORSA software for Linux and Windows to create the animation above and to calculate the following numbers based on MPC data posted since the announcement MPEC:

Closest18 AprilTime EDTAULD
Earth0018 UT8:18pm 17 April0.0018490.722
Moon0546 UT1:46am 18 April0.0016360.639

Note: A/CC first posted news about 2004 HE with the cover image at 1636 UTC (12:36pm EDT) on April 17th.

News briefs – panel 1/1 Major News for 17 April 2004 back top next  
News briefs

Comet Bradfield late news:  At last check there is an unexplained 19-hour gap in the SOHO image record of C/2004 F4 (Bradfield)'s perihelion passage, but regular postings have resumed beginning with a 2354 UT partial image from the 17th. See here or here.

Meteor news:  Astrobiology Magazine has pictures and additional information in an article yesterday about the Antarctic meteorite that matches "Bounce Rock" examined on Mars by the rover Opportunity (see JPL's April 15th news release).

Another Sandia all-sky camera bright meteor from Albuquerque, New Mexico has been posted (408Kb Quicktime movie, temporary link) from Thursday morning, the fifth in four weeks.

A University of Illinois at Urbana-Champaign news release from April 15th tells about repurposing a LIDAR (LIght Detection And Ranging) system designed to detect meteor trails to study "the removal of meteoric iron by polar mesospheric clouds . . . during the summer at the South Pole."

Model of 25143 Itokawa from radar 
observation, courtesy of JAXA
Illustration courtesy of JAXA

Hayabusa news:  The Japanese space agency JAXA Projects page for its MUSES-C Hayabusa mission posted this "thumbnail" yesterday and reported that the shape of the mission destination, NEO 25143 Itokawa, had been determined by JPL's Steve Ostro using radar observation from Arecibo. No larger illustration or other details are given.
Update:  Thanks to Gilbert Javaux who shares with A/CC readers that Steve Ostro's report, images (see especially), and shape model are here.

Hubble news:  Space.com has an article today, "Hubble Space Telescope Study Group Selected," about "A newly formed 20-person blue-ribbon panel that includes scientists, former astronauts, NASA managers, aerospace industrialists, a member of the Columbia Accident Investigation Board, and a robot expert." See also the Baltimore Sun's report today and Space.com's story yesterday, "Robotic Hubble Servicing Mission Plans Under Review."

Risk monitoring - panel 1/1 Major News for 17 April 2004 back top next  
Risk monitoring 17 April

There is no news to report today about risk monitoring, as there are no observations reported in the Saturday Daily Orbit Update MPEC for the two objects currently in view that have impact solutions. 2004 GA1 will be in view until July, according to the European Spaceguard Central Node Priority List, but 2004 GE2 will be in view for only about ten more days.

Summary Risk Table - sources checked at 2358 UTC, 17 Apr

Object

Assessment

Years

VI
PS
cum
PS
max
T
S
Arc 
days
 2004 GE2JPL 4/162094-21035-4.53-4.8102.643
 2004 GA1 NEODyS 4/162026-20805-2.71-2.8503.978
JPL 4/162026-209911-2.76-3.0203.978
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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