Grupa: Użytkownik
Posty: 787 #2030651
Od: 2011-9-14
| Poniżej ciekawy tekst z 'moon-net' o możliwości obserwacji echa radarowego od asteroidy, która jutro będzie najbardziej zbliżona do Ziemi.
73's de Staszek SP6GWB
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AMSAT News Service Bulletin 025.01
From AMSAT HQ Kensington, MD.
January 25, 2015
To All RADIO AMATEURS
BID: $ANS-025.01
Listen In To Radar Observations of Near-Earth Asteroid 2004 BL86
On 2015 January 26, the near-Earth asteroid 2004 BL86 will pass within
0.008 AU
of Earth (3.1 times as far away as the Moon). This will be the closest
approach
to Earth by this asteroid for at least the next 240 years.
As part of an extensive campaign of radar observations to learn about
BL86’s shape, spin state, and surface; and to refine knowledge of its
trajectory; the Arecibo Observatory’s S-band planetary radar plans to
illuminate
the asteroid with a continuous-wave signal over 2015 January 27 03:45 –
04:00
UTC. Over that time, BL86’s radar echo will be received by elements of
the Very
Long Baseline Array and the Very Large Array in New Mexico. Anyone with an
antenna and receiver capable of detecting the echo is welcome to listen in.
BL86 will be above the horizon for most observers in North and South
America,
and for some parts of western Europe and western Africa. To readily
detect its
radar echo, observers should have an antenna with an effective
collecting area
of at least 10 square meters. BL86 will be moving rapidly across the
sky. Over
Jan 27 03:45 – 04:00, it will move by ~0.5º. The asteroid’s exact
position on
the sky will depend on where it is observed from as well as the time,
but will
be near (RA,Dec) = (130º,+17º . A current ephemeris can be obtained
from JPL’s
Horizons system:
http://ssd.jpl.nasa.gov/?horizons.
The Arecibo transmission will be tuned to give a nominal echo center
frequency
of exactly 2380 MHz at geocenter. Without correction for Earth’s rotation,
BL86’s radar echo will appear as slowly-drifting and within 15 kHz of
2380 MHz.
Predicted echo frequency as a function of time for a given location can be
obtained on-request by emailing Michael Busch (mbusch@seti.org). We
expect an
echo bandwidth of 6 Hz or less.
Details of the BL86 radar observing campaign at the Arecibo Observatory,
NASA’s
Goldstone Solar System Radar facility, and the National Radio Astronomy
Observatory are available at:
http://echo.jpl.nasa.gov/asteroids/2004BL86/2004BL86_planning.html.
[ANS thanks JPL for the above information] |
