|Friday||26 December 2003||6:57pm MST||2003-12-27 UTC 0157|
New-found objects: From the 23rd through this morning, eight objects were announced by the Minor Planet Center. Five of these were first spotted by LINEAR on 22 December in New Mexico, and the latest announcement, 2003 YN107, was found by LINEAR on the 20th. 2003 YQ94 was discovered with the Spacewatch 0.9m telescope on the 22nd in Arizona, and 2003 XB22 was first noticed with the 1m telescope at Siding Spring in Australia back on the 15th, but not followed further until the 24th. Of these eight objects, three are now listed with impact solutions — XB22, YQ94, and 2003 YS70 (see below), and half of them, including YN107 and YS70, are small objects with absolute magnitudes (brightness) greater than H=22.0.
Francesco Manca tells A/CC that 2003 YN107 "has had a close approach with the Earth on December 21st at 0.0148 AU, or 5.75 lunar distances." On the Minor Planet Mailing List (MPML) today, the question was raised about whether YN107 with its near-zero inclination might be space junk. Dr. Alan Harris responded about this using comparison with 2003 YS70, 2003 WT153, and J002E3:
In nature, asteroids and such get transferred into Earth-crossing orbits from perturbations (encounters) with other planets, so there is a natural minimum relative velocity "barrier" for natural objects of around 2.7 km/sec. . . J002E3 is way under that [while] 2003 YN107 and 2003 YS70, and also 2003 WT153, have Earth encounter velocities sufficient to make it to the neighboring planets [and in fact] the present orbit of WT153 makes it to Venus and YS70 makes it to Mars. . . [At H=29.8, YS70] is small enough to be an Agena rocket or other similar fairly small booster. . . WT153 is most suggestive of being space junk, as it is in a Venus-crossing orbit [and] lots of stuff goes first to Venus on its way [to elsewhere in] the outer solar system. . . Of the three, I'd say YN107 is very unlikely to be artificial, YS70 more likely, but still unlikely, and WT153 most likely of the three, although still not a "dead ringer", like J002E3.
|News briefs, part 2||
SOHO public participation: The SOHO space mission has resumed support for public comet discoveries over the Internet. Karl Battams introduced himself to the SOHO chat page on December 19th and has posted messages since then explaining progress in clearing up the discovery backlog. A/CC reported on October 18th about how support for public participation had come to a halt in August.
Recovery/follow-up: There were more update than discovery MPECs during 23-26 December, with follow-up for five near-Earth objects (two potentially hazardous) and ten Edgeworth-Kuiper Belt objects (EKBOs) that come no closer to the Sun than about 28 times the distance between Earth and Sun, and that have median width estimates of 80 km. (50 miles) to 330 km. (205 miles).
All ten EKBO update MPECs involve the work of Lowell Observatory's Deep Ecliptic Survey (DES), mostly using the Kitt Peak 4m telescope in October and November, but also including work from smaller telescopes and some archive sleuthing.
MPEC 2003-Y50 updates 2003 UY117, discovered October 22nd this year with the 0.9m Spacewatch telescope. DES followed up on 23-24 November with two 3m+ telescopes at Kitt Peak, and Bill Yeung caught it on 20 and 22 December with his 0.45m telescope. Plus Reiner Stoss found this object in NEAT/Palomar archives back to 26 July 2001.
Besides DES observing, MPEC 2003-Y51 has observations of 2002 XV93 from Wolf Bickel with the Bergisch Gladbach Observatory 0.6m telescope on 17-18 December, and MPEC 2003-Y55 for 2002 XW93 has Erich Meyer using the Linz Observatory 0.6m telescope for observations from December 23rd. This last EKBO, which was discovered by NEAT in December 2002 with its Mt. Palomar telescope, was found by Reiner Stoss in the NEAT archives from a year earlier, and in scanned plates from the same telescope from 1993 and 17 December 1989. And DES found one EKBO, 2001 UN18, in its own archives from November 2002, in addition to reporting new observations (MPEC 2003-Y52).
Three of five concerns under current observation were reported in Friday's Daily Orbit Update MPEC (DOU). Tenagra II Observatory in Arizona observed 2003 YD45 yesterday morning and Consell Observatory in Spain got it last night. Today JPL very slightly lowered its overall YD45 risk assessment while NEODyS raised its ratings.
2003 YS70 was reported from yesterday morning by Tenagra II and Desert Moon Observatory in New Mexico, and the Observatorio Astronomico de Mallorca (OAM) followed it in multiple observing sessions that spanned seven hours and 39 minutes from last night into this morning. Both risk monitors today lowered their risk ratings for this tiny object.
Missing from the DOU are 2003 XB22 and 2003 YE45.
Update 1904 UTC: NEODyS has posted 2003 YQ94, a kilometer-size object that was announced yesterday in MPEC 2003-Y73.
2003 YQ94 was discovered by Andrew Tubbiolo with the Spacewatch 0.9m telescope Monday morning in Arizona and immediately followed up by the Spacewatch 1.8m telescope. KLENOT in the Czech Republic caught it Wednesday night and the Spacewatch 1.8m and Sabino Canyon Observatory in Arizona finished out the confirmation process yesterday morning. Today's DOU reported observations from Siding Spring Observatory yesterday in Australia.
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