Bolide Prediction

Folks - this came through on the MPML today. A large bolide is predicted for the early hours of the morning (Tuesday 7th) and may be visible from Southern Europe - that may rule out Ireland but you never know...

This is mostly the original post with some edits I made with updated information:


Hi folks,

It looks as if Mt. Lemmon has found the first object (currently on NEOCP) with a near certainty of hitting the earth. It won't be anything more than a spectacular meteor (H=30.5), and the orbit isn't solid enough to say exactly where and when it will hit... too bad; I'm never looking the right way when a nice meteor appears.

The nominal perigee distance is 5866 km.
The Earth's equatorial radius is 6378 km. Impact time would be a few minutes before the nominal perigee time, October 7 at 1:53 UT.


The time of entry into the atmosphere is now appr. 2:34 UT, Oct 7. I don't have a software that displays the situation, but from the alt/az ephems for our station (J75) it seems that it will enter atmosphere approaching from southwest, at azimuth 46° and altitude 48°, heading quickly over the sky to southeast. Southwestern Mediterranean? Morocco?
Algeria? Or Southern Europe even?

The nominal perigee distance is 2500km now with the latest data from D90 and E12.

UPDATE:

Today the object with the provisional designation 8TA9D69 was submitted to impact monitoring by using the normal software of the NEODyS system, by using the observations as reported by the MPC on the NEO Confirmation Page.

The results were as follows (this is the Risk file in the usual format)

Object: 8TA9D69

date MJD sigma sigimp dist +/- width stretch p_RE exp. en. PS
YYYY/MM (RE) (RE) RE/sig MT

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2008/10/07.116 54746.116 2.824 0.000 1.91 +/- 0.001 4.01E-03 9.98E-01 6.01E-04 1.69


Based on 26 optical observations (of which 0 are rejected as outliers)
from 2008/10/06.278 to 2008/10/06.643.

Coordinates are given on the Target Plane Unit is one Earth radius, but impact cross section has radius between 2.02 and 2.02 Earth radii

The probability of impact is, according to different computations done in slightly different ways, between 99.8% and 100%; in practice the impact can be considered sure and is for tonight. Our computation has already been confirmed independently by others, including the JPL NEO group (with which we consult in all relevant cases of possible impact).

The other important result is that the confidence ellipse for the arrival of this object on the atmosphere is very small, thus it is possible to predict this atmospheric entry point within tens of kilometers. Unfortunately we are not equipped to do this computation on short notice, but others are doing this (some already have).

The effect of this atmospheric impact will be the release, in either a single shot or maybe a sequence of explosions, of about 1 kiloton of energy. This means that the damage on the ground is expected to be zero. The location of these explosions is not easy to predict due to the atmospheric braking effects. The only concern is that they might be interpreted as something else, that is man-made explosions. Thus in this case, the earlier the public worldwide is aware that this is a natural phenomenon, which involves no risk, the better.

The NEODys team

Andrea Milani, Maria Eugenia Sansaturio, Fabrizio Bernardi, Giovanni B. Valsecchi

UPDATE:

www.cfa.harvard.edu/mpec/K08/K08T50.html

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The nominal orbit given above has 2008 TC3 coming to within one earth radius around Oct. 7.1. The absolute magnitude indicates that the object will not survive passage through the atmosphere.

Steve Chesley (JPL) reports that atmospheric entry will occur on 2008 Oct 07 0246 UTC over northern Sudan.

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Interesting. From my (brief) read over of the updates, none of them indicate a size of the object, yet it is big enough to be tracked, and with certainty, will not survive atmospheric entry. How do they come up with this stuff?

Seanie.

I don't know Seanie how they reckon it will not survive the entry, they have barely enough time to see this one coming, should be some sight though, I wonder will anyone get a shot, it would be amazing :woohoo:

Keith..

Seanie - they work off the absolute magnitude of the object, which is listed at about mag 30.4 That makes it just a few meters across.

For your information, this is receiving a lot of attention and is being tracked by a good few observers. The MPC are issuing updated information a few times per hour!

Here's the official IAU Circular (8990):



2008 TC_3
A small asteroidal object (absolute magnitude H = 30.4, suggesting a few meters in size) discovered by the Mt. Lemmon Survey (observer R. A. Kowalski) on Oct. 6.28 UT at Delta = 0.0033 AU (about 1.27 the moon's distance from the earth) will enter the earth's atmosphere over northern Sudan (according to S. Chesley, Jet Propulsion Laboratory) around Oct. 7.115, moving east to west.
Prior to entering the atmosphere, it may be around visual mag 11.
Astrometry, orbital elements, and ephemerides are given on MPECs 2008-T50, 2008-T51, and 2008-T52.