The Asteroid/Comet Connection's
daily news journal about
asteroids, comets, and meteors
Today's issue status: done
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|
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.
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
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.
|Risk monitoring - part 1/1||Major News for 29 Feb. 2004|
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.
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).