By Roger W.
Sinnott - Associate Editor Sky & Telescope
On August
26, 2000, the NEAT/MSSS survey (Eleanor F. Helin and colleagues)
picked up an unusually bright near-Earth asteroid with its 1.2-m
reflector on Haleakala, Hawaii. In an electronic circular issued
this afternoon, Gareth V. Williams of the Minor Planet Center
( http://cfa-www.harvard.edu/iau/mpc.html
) in Cambridge, Massachusetts, designated this object 2000 QW7.
About magnitude
13.6 when first detected, the asteroid will brighten to 12.7 within
the next week as it makes a moderately close flyby, coming within
0.032 astronomical unit of Earth (about 12 Earth-Moon distances)
in the first few days of September. Anyone with an 8-inch or larger
telescope and clear, dark skies should have no trouble spotting
the object visually during this period as it glides from Aquarius
through Pisces into Cetus. Small CCD-equipped telescopes can also
capture trailed images of 2000 QW7. (See the detailed ephemeris
at the end of this AstroAlert.)
As soon as
NEAT astronomers reported the object, the Minor Planet Center
posted the position and direction of motion on the NEO Confirmation
Page of its Web site. Within the next 30 hours, a total of 115
precise positions had arrived from 19 astrometric observatories
around the world (including 7 positions obtained by the undersigned
at the Drum Hill Station in northern Massachusetts). Williams
then issued on Minor Planet Electronic Circular 2000-Q32, containing
the following preliminary orbital elements (equinox 2000.0):
Epoch
2000 Aug. 24.0 TT
Mean anomaly, M
353.92092
Semimajor axis, a
1.9510626
Eccentricity, e
0.4694395
Arg. of perihelion
190.39996
Long. of ascending node 158.81329
Inclination, I
4.16947
The elements
show that this asteroid belongs to the Amor family and follows
an orbit inclined 4.2 degrees to the ecliptic. It ranges as far
out as the main belt of asteroids (roughly midway between Mars
and Jupiter), but every 2.7 years it comes in to a point fairly
close to the Earth's orbit. As far as is currently known, the
object has not been detected by astronomers before. Its brightness
suggests it may be about a half mile (0.8 kilometer) across.
The following
ephemeris, calculated at Sky & Telescope from the above elements,
gives the object's right ascension and declination at 6-hour intervals
for the next two weeks. Also listed is its distance from the Earth
(Delta) and the Sun (r) in a.u., expected visual magnitude, and
the constellation through which it is passing.
When searching
for the asteroid, keep in mind the parallax effect. Because the
object is so close to the Earth in the next few days, it can appear
displaced up to about 5 arcminutes from the geocentric positions
tabulated below. (HINT: to make the numbers line up in straight,
vertical columns, set your e-mail program to display this message
in a font such as Courier that
does not use proportionally spaced letters.)
Roger W. Sinnott
Associate Editor
Sky & Telescope
Ephemeris
for Minor Planet 2000 QW7
Date UT
R.A. (2000) Dec. Delta
r Mag. Const.
2000 Aug 27 0h 21 33.1 -03
39 0.038 1.047
13.4 Aqr
2000 Aug 27 6h 21 37.9 -03
41 0.038 1.047
13.3 Aqr
2000 Aug 27 12h 21 42.7 -03 44
0.037 1.047 13.3 Aqr
2000 Aug 27 18h 21 47.8 -03 46
0.037 1.046 13.2 Aqr
2000 Aug 28 0h 21 52.9 -03
49 0.036 1.046
13.1 Aqr
2000 Aug 28 6h 21 58.2 -03
51 0.036 1.045
13.1 Aqr
2000 Aug 28 12h 22 03.6 -03 53
0.035 1.045 13.0 Aqr
2000 Aug 28 18h 22 09.2 -03 56
0.035 1.045 12.9 Aqr
2000 Aug 29 0h 22 14.9 -03
58 0.034 1.044
12.9 Aqr
2000 Aug 29 6h 22 20.7 -04
00 0.034 1.044
12.8 Aqr
2000 Aug 29 12h 22 26.6 -04 02
0.034 1.043 12.8 Aqr
2000 Aug 29 18h 22 32.7 -04 04
0.033 1.043 12.7 Aqr
2000 Aug 30 0h 22 38.8 -04
06 0.033 1.043
12.7 Aqr
2000 Aug 30 6h 22 45.1 -04
07 0.033 1.042
12.7 Aqr
2000 Aug 30 12h 22 51.5 -04 09
0.033 1.042 12.7 Aqr
2000 Aug 30 18h 22 58.0 -04 10
0.032 1.042 12.7 Aqr
2000 Aug 31 0h 23 04.5 -04
11 0.032 1.041
12.8 Aqr
2000 Aug 31 6h 23 11.1 -04
12 0.032 1.041
12.8 Aqr
2000 Aug 31 12h 23 17.8 -04 13
0.032 1.041 12.9 Aqr
2000 Aug 31 18h 23 24.5 -04 14
0.032 1.040 12.9 Aqr
2000 Sep 1 0h 23 31.2
-04 14 0.032 1.040
12.9 Aqr
2000 Sep 1 6h 23 38.0
-04 14 0.032 1.040
13.0 Aqr
2000 Sep 1 12h 23 44.8 -04
14 0.032 1.040
13.0 Aqr
2000 Sep 1 18h 23 51.6 -04
14 0.032 1.039
13.1 Aqr
2000 Sep 2 0h 23 58.4
-04 14 0.032 1.039
13.1 Psc
2000 Sep 2 6h 0 05.2
-04 13 0.032 1.039
13.2 Psc
2000 Sep 2 12h 0 11.9
-04 12 0.032 1.039
13.2 Psc
2000 Sep 2 18h 0 18.5
-04 11 0.032 1.038
13.3 Psc
2000 Sep 3 0h 0 25.1
-04 10 0.032 1.038
13.3 Psc
2000 Sep 3 6h 0 31.7
-04 09 0.032 1.038
13.4 Cet
2000 Sep 3 12h 0 38.1
-04 07 0.033 1.038
13.4 Cet
2000 Sep 3 18h 0 44.5
-04 05 0.033 1.038
13.5 Cet
2000 Sep 4 0h 0 50.7
-04 03 0.033 1.037
13.5 Cet
2000 Sep 4 6h 0 56.9
-04 01 0.033 1.037
13.6 Cet
2000 Sep 4 12h 1 02.9
-03 59 0.034 1.037
13.6 Cet
2000 Sep 4 18h 1 08.8
-03 57 0.034 1.037
13.7 Cet
2000 Sep 5 0h 1 14.6
-03 54 0.034 1.037
13.8 Cet
2000 Sep 5 6h 1 20.3
-03 52 0.035 1.037
13.8 Cet
2000 Sep 5 12h 1 25.8
-03 50 0.035 1.036
13.9 Cet
2000 Sep 5 18h 1 31.3
-03 47 0.035 1.036
13.9 Cet
2000 Sep 6 0h 1 36.5
-03 44 0.036 1.036
14.0 Cet
2000 Sep 6 6h 1 41.7
-03 42 0.036 1.036
14.0 Cet
2000 Sep 6 12h 1 46.7
-03 39 0.037 1.036
14.1 Cet
2000 Sep 6 18h 1 51.5
-03 36 0.037 1.036
14.1 Cet
2000 Sep 7 0h 1 56.3
-03 33 0.038 1.036
14.2 Cet
2000 Sep 7 6h 2 00.9
-03 30 0.038 1.036
14.2 Cet
2000 Sep 7 12h 2 05.3
-03 28 0.039 1.036
14.3 Cet
2000 Sep 7 18h 2 09.7
-03 25 0.039 1.035
14.4 Cet
2000 Sep 8 0h 2 13.9
-03 22 0.040 1.035
14.4 Cet
2000 Sep 8 6h 2 18.0
-03 19 0.041 1.035
14.5 Cet
2000 Sep 8 12h 2 21.9
-03 17 0.041 1.035
14.5 Cet
2000 Sep 8 18h 2 25.8
-03 14 0.042 1.035
14.6 Cet
2000 Sep 9 0h 2 29.5
-03 11 0.042 1.035
14.6 Cet
2000 Sep 9 6h 2 33.1
-03 08 0.043 1.035
14.7 Cet
2000 Sep 9 12h 2 36.6
-03 06 0.044 1.035
14.7 Cet
2000 Sep 9 18h 2 40.0
-03 03 0.044 1.035
14.8 Cet
2000 Sep 10 0h 2 43.3
-03 01 0.045 1.035
14.8 Cet
2000 Sep 10 6h 2 46.5
-02 58 0.046 1.035
14.9 Eri
2000 Sep 10 12h 2 49.6 -02
56 0.046 1.035
14.9 Eri
2000 Sep 10 18h 2 52.6 -02
54 0.047 1.035
14.9 Eri
2000 Sep 11 0h 2 55.5
-02 51 0.048 1.035
15.0 Eri
Mitch Battros
Producer - Earth Changes TV
http://www.earthchangesTV.com
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