2008TC3:
This object was discovered by R.A. Kowalski of the Mount Lemmon Survey
(MPC G96) at 06:40UT on 2008 Oct. 06 at a distance of 0.00329AU. A report was
made soon after discovery that this small object, with H=30.673 according to
the JPL ephermeris, corresponding to a diameter of a few metres, could impact
the Earth early on October 7th. This was not the first prediction of
this kind to have been made, but as the orbit improved it rapidly became
obvious that the initial assessment was correct and a trajectory termination
point could be determined, giving a presumed impact in
MPC Code |
Name |
Site |
First |
Last |
No. astrometry |
No. Photometry |
213 |
Ramón Naves
& Montse Campàs |
|
20:22 |
00:11 |
50 |
50 |
J47 |
Gustavo Muler |
Lanzarote |
21:08 |
23:13 |
125 |
125 |
J51 |
Juan Antonio Henríquez |
|
21:56 |
21:58 |
3 |
3 |
J53 |
Rafael
Benavides |
|
21:44 |
01:24 |
15 |
15 |
J95 |
Peter
Birtwhistle |
Great |
19:20 |
23:44 |
16 |
13 |
Total |
|
|
19:20 |
01:24 |
209 |
206 |
In total the asteroid was followed for 6h4m from the five sites. The
observations by J51 were curtailed by cloud, whilst J95 suffered from cloud
interruptions. J53 reported that the velocity of the asteroid was too high at
the end to allow reliable photometry to be taken from the images. The light
curve from the data can be seen below. Significant scatter is seen at the
beginning and the end due to the difficult conditions of observation. Initially
the asteroid brightened relatively slowly, from R=16.6 at 19:29UT to R=15.3 at
23:10UT (0.35 mags/h), before accelerating to R=13.5 at 01:23UT when the last
observations were made (1.5 mags/h). We see that the observed CCD light curve
in R is about 0.9 magnitudes brighter than the JPL geocentric ephemeris in V,
part of which is due to the observers being on the surface of the Earth and not
at it centre and part due to the (V-R) colour index of the asteroid, although
it does genuinely seem a little brighter than the assumed absolute magnitude.
Given the object’s small and rapidly decreasing geocentric distance,
parallax became an important effect for observers, even separated by relatively
small distances. Of the five sites that have reported data here, one was in
southern
06/10/2008 21:50 |
23 |
33 |
41.76 |
8 |
8 |
17.7 |
15.6 |
R |
J53 |
06/10/2008 21:50 |
23 |
35 |
21.28 |
8 |
30 |
44.2 |
15.9 |
C |
J47 |
06/10/2008 21:52 |
23 |
32 |
31.51 |
7 |
59 |
31.4 |
15.7 |
R |
213 |
06/10/2008 22:42 |
23 |
33 |
58.29 |
8 |
2 |
50.6 |
15.6 |
R |
213 |
06/10/2008 22:42 |
23 |
37 |
11.45 |
8 |
42 |
10.5 |
15.6 |
C |
J47 |
06/10/2008 22:45 |
23 |
35 |
27.03 |
8 |
14 |
32.8 |
15.5 |
R |
J53 |