Sunday18 January 20045:39pm MST2004-01-19 UTC 0039 back top next  

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

Today's issue status: done

Today's cover shows how a faint fast-moving object is tracked down. As Peter Birtwhistle at Great Shefford Observatory tells on his 2003 RU11 page, this object, first designated AH79759 and estimated now at 20-50 meters wide, was posted to the Minor Planet Center NEO Confirmation Page last year after discovery by LINEAR. He made two passes making multiple exposures of each overlapping field in the "uncertainty area," but didn't find the object until the next night, when a better orbit calculation from further LINEAR observations helped him re-examine his images, finding it in the two frames shown at 200% at top.

Small objects – part 1/1 Major News for 18 Jan. 2004 back top next  
Small objects

Since A/CC's last seven-day report on tracking the smallest near-Earth asteroids — some of our closest neighbors, three more have been announced. "Smallest" is by absolute magnitude (brightness) of H>22.0 — the line beyond which asteroids can't fall into the category of "potentially hazardous" (PHA). In the usual absence of other information, higher H is interpreted to mean smaller. But small won't keep an object off the risk monitors' lists, and 2004 BY1 (H=25.0) was posted to JPL's list today, as reported below.

The two other new-found small objects are 2004 AD1 (H=22.4) and 2004 AE6 (H=24.7). Lowell Observatory shows that AD1 would be categorized as a PHA if larger, while AE6 is only a risk to Mars. 2004 AD1 was announced in MPEC 2004-A53 on January 14th, discovered the day before by LONEOS with follow-up from Table Mountain, Great Shefford, and Highworth observatories. It has since been reported by Great Shefford (twice) as well as Powell, Sormano, and Tenagra II observatories.

Earth's tiniest neighbors on 18 Jan. 2004
Green dots are H>22.0 NEAs
Circled were observed last week
Adapted from EasySky screen shots
Ecliptic grid set to 10 lunar distances

Announced yesterday in MPEC 2004-B04, 2004 AE6 was discovered January 15th with the Spacewatch 0.9m telescope, which spotted it again the next morning, and Tenagra II confirmed it yesterday morning.

Pursued further this last week was 2004 AD (H=24.4), subject of last Sunday's cover. It was reported from 11, 13, 16, and 17 January by Great Shefford, and from the 12th by Tenagra II, as well as from the 10th by San Marcello Pistoiese Observatory. Tenagra II reported 2003 YR117 (H=22.9) from the 12th, Powell observed 2003 YT70 (H=25.8) on the 13th, and Great Shefford caught Earth co-orbital candidate 2002 AA29 [link|alt] (H=24.1) on the 15th.

The median inexact size estimates for the objects in this report, with H from 25.8 to 22.4, range by standard formula from 24 to 114 meters/yards wide, within maximum extents on the order of 18-197 meters.

News briefs – part 1/1 Major News for 18 Jan. 2004 back top next  
News briefs
C/2003 WT42 (LINEAR)
where it is today
EasySky screen shot
Ecliptic grid set to 1 AU

C/2003 WT42:  The German Comet Section yesterday posted brief details about how C/2003 WT42 (LINEAR) was caught displaying cometary activity, seen with optical and infrared telescopes of sizes 2.5 to 4 meters. Friday's MPEC 2004-B02 doesn't incorporate astrometry from those telescopes, but it does publish a non-elliptical path for this object with e=1.00183 and perihelion put at 11 April 2006. That leaves plenty of time to accumulate better orbital data for this large object that appears to be on a one-way trip around the Sun and out of our Solar System.

The screen shot above from EasySky shows where C/2003 WT42 (LINEAR) is today, and the path it is taking through the center of the Solar System.

Readings: yesterday posted the January 15th edition of David Morrison's NEO News E-mail newsletter with a review of the philosophical question, "Has the Spaceguard Survey made us any safer?" The E-mailed version apparently also included the text of Jim Oberg's USA Today opinion piece, "Think outside moon-Mars box: Maybe visit asteroid?" It offered an alternative vision for NASA's future just ahead of President Bush's January 14th speech.

Deep Impact:  The Deep Impact mission has a reminder on its home page that the 31st of this month is the deadline for signing up for the mission's Send Your Name to a Comet campaign.

Risk monitoring - part 1/1 Major News for 18 Jan. 2004 back top next  
Risk monitoring 18 Jan.

JPL today posted 2004 BY1 with two very low rated impact solutions in 2090, beyond the NEODyS time horizon. This object, estimated by JPL to be roughly 40 meters/yards wide, was announced today in MPEC 2004-B10. It was discovered NEAT's Air Force telescope on Haleakala in Hawaii yesterday and first confirmed last night by Ondrejov Observatory in the Czech Republic. The confirmation process was closed out this morning by Great Shefford Observatory in England and Grasslands Observatory in Arizona.

JPL today removed its one impact solution for the kilometer-plus 2003 YG118 following observations reported in Sunday's Daily Orbit Update MPEC (DOU) from early yesterday from Hudson, Egan, and McCarthy observatories in New York, Florida, and Connecticut. The DOU also carries observations of YG118 from McCarthy from January 1st and 11th.

Summary Risk Table - sources checked at 0037 UTC, 19 Jan




 2004 BY1JPL 1/182090-20902-7.73-8.0200.845
 2004 BV1JPL 1/182010-2103120-3.61-4.0202.121
 2003 YG118JPL 1/18R E M O V E D
NEODyS 12/31R 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.

1927 UTC update:  JPL has posted 2004 BV1, which was announced today in MPEC 2004-B08 as having been discovered Friday morning with the Spacewatch 0.9m telescope in Arizona, followed up by the same yesterday, and this morning by it and Grasslands Observatory in Arizona. From its brightness, 2004 BV1 is estimated by standard formula to be on the order of 325 meters/yards in diameter.
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