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

Today's issue status: done, updated

• News briefs – PHA now PHC & Rosetta news + bits & pieces
  panel 2 – Queensland event & space surveillance
• Risk monitoring
  – NEODyS has posted 2004 FE31
  & JPL has posted 2004 FY31

Cover: Juan Lacruz participated in the discovery confirmation of comet P/2004 F1 (NEAT) during the night of 18-19 March, working from his La Canada Observatory in Spain, as seen at left and reported in MPEC 2004-F39 of the 19th.

PHA now PHC:  From February 5th to 15th, 2004 CB was listed with impact solutions. Today it was redesignated as comet P/2004 CB (LINEAR) with MPEC 2004-F96, which has observations with the 1.0m telescope used by the Siding Spring Survey. Perihelion will be just inside Earth's orbit (0.912 AU) on April 2nd at more than 0.44 AU from Earth.

There are 41 other potentially hazardous comets (PHCs), of which all but 15 are numbered. JPL had the asteroid's absolute magnitude at H=16.33. If that calculation came from inactive surface brightness, then this object as a dark comet nuclei could be upwards of 4 km. (2.5 miles) in diameter, but smaller if biased by cometary activity.

Using ORSA with today's MPEC data, Pasquale Tricarico tells A/CC that, after 2004 CB flies by Earth at 0.26 AU in April 2009, it will come within 0.59 AU of Jupiter in 2012, giving it "a significant kick to the orbital elements," leading to an Earth flyby at 0.055 AU (21.5 LD) on 29 May, ten years from now.

Rosetta news:  The European Space Agency has an item from yesterday that explains why landing on a comet surface at what amounts to a slow walk (one meter/second) is not so easy. The Rosetta mother ship will send the little lander on its way with a "gentle push" from low altitude to tackle unknown conditions with shock-resistant, tilt-limited landing gear, harpoons, and, in case the surface is powdery, wide landing pads.

Bits & pieces:  About "From brightness to size," Petr Scheirich informs A/CC of his page with a magnitude-to-diameter conversion chart and table. Also nicely done is his Asteroid Groups page.

Additional to yesterday's news about the hundred-year-old Scotland fall, that meteorite is being put on public display in Glasgow. See report.

Xinhua reports today that the Nanjing Purple Mountain Observatory, which "has discovered about 1,000 asteroids, among which more than 100 can be named by the Observatory," has received "the go-ahead domestically" to propose to the IAU naming one of them for China's first astronaut, Yang Liwei.

more news briefs >>

<< continued from panel 1

Queensland event:  Many Australian news outlets have items dated April 1st about "scores of reports about a large fireball seen in the sky over Queensland's north and central west last night" at about 7pm local time, accompanied by an explosion and reported ground shaking. One account called it "like a kite on fire"

• ABC Far North Queensland, "Qld abuzz with fireball yarns"
• The Age, "Fireball shakes town in Qld"
• ABC Far North Queensland, "Large fireball sighted over Qld"
• ABC Queensland, "Qld residents spot large fireball in the sky"
• Townsville Bulletin, "Space rock hits the North"
• Brisbane Courier-Mail, "Light show startles residents"

  “ "I looked up and in the north-east there was this bloody big fireball, like a kite on fire. Then I heard this explosion and everyone ran out into the street to see what was going on because the houses were shaking." [Account by a Winton resident who "said the object left a trail of white vapour after it disappeared."] ”

Notes: "ABC" here refers to the Australian Broadcasting Corporation. News of this event was first posted on A/CC at 2053 UTC.

Space-based surveillance:  Boeing has a news release from yesterday that it and Ball Aerospace have won a contract "to develop and initially operate the Space-Based Space Surveillance System (SBSS) for the U.S. Air Force" to detect and track "space objects, such as satellites and orbital debris." The SBSS satellite is "to be launched by mid to late 2007."
      Nothing is said about tracking NEOs. Boeing is the prime contractor for the Maui Space Surveillance System where JPL's NEAT program piggybacks asteroid tracking onto military missions using first a 1.0m and now a 1.2m telescope. And this is part of the same Air Force operations that include two telescopes at White Sands in New Mexico used by LINEAR. But these operations also include telescopes that aren't available for watching natural near-Earth objects.

Risk monitoring 31 March

NEODyS has posted 2004 FE31 which was announced today in MPEC 2004-F93 as discovered yesterday by Jim Scottie early Monday with the Spacewatch 0.9m telescope in Arizona and followed up yesterday morning with the Spacewatch 1.8m telescope and Tenagra II Observatory in Arizona, and early today by Powell Observatory in Kansas. From its brightness, it is roughly estimated at 700 meters/yards wide.

The Wednesday Daily Orbit Update MPEC carries no observation of 2004 FN18 but has observations of 2004 FU4 from yesterday morning from the Spacewatch 1.8m telescope and from Jornada Observatory in New Mexico. Today NEODyS cut its impact solution count by two and lowered its overall risk ratings for this object. JPL only slightly lowered its risk ratings but cut its solution count from 27 to 14.

The MPC Last Observation page is showing that 2004 FU4 was caught with the Spacewatch 1.8m telescope this morning, and 2004 FE31 by Desert Moon Observatory in New Mexico.

Update:  Both NEODyS and JPL have revised their 2004 FU4 risk assessments based on the same data used for their earlier updates. Each cut its impact solution count by one. NEODyS has further lowered its overall risk ratings for 2004 FU4, but JPL has very slightly raised its ratings for a longer time horizon.

Late update:  JPL has posted 2004 FY31, announced on the 31st in MPEC 2004-F98 as discovered earlier this day by LONEOS in Arizona.