Last updated 2010 February 4
Welcome to the web site of the
of the
British Astronomical Association
The
Site Guide may help you to find your way
around the site. The What
to observe page lists many different aspects of observing
and imaging together with current projects.
The long-term objective is that the Section should be able to offer something to
active, virtual and armchair observers eg; visual telescopic observing, imaging
(photographic, CCD, webcam), virtual observing using on-line resources, orbital
motion, the impact hazard, history of
discovery and observation, general understanding of the planets and
minor planets and space missions to those bodies.
Health and Safety
A much maligned topic but one that
really should be taken seriously. One ARPS member recently had quite a nasty
accident when he fell over when walking from his observatory back to his house
in the dark. If you are planning to be out observing in the middle of the night
please take a few minutes to consider the consequences of what might happen if
you were to be incapacitated in any way.
News
And
finally …. (see bottom of page)
A
four-disk
PLANOCCULT/H.
Pavlov. In March this year the
asteroid 2009 DD45 come very close to the Earth and became bright enough to be
observed by amateurs. Back then
As a result a guide to video astrometry was put together and made available. It can be downloaded from the MPC web site: http://www.cfa.harvard.edu/iau/info/VideoAstrometry.pdf
Now
there is another NEO which is coming close to us. It will not be as fast as
DD45 but will be almost as bright. On
Knowing the position of the target is essential and to get an accurate ephemeris you will need to use the MPC ephemeris service: http://www.cfa.harvard.edu/iau/MPEph/MPEph.html
From 2009 DD45, I remember that finding the target was the most difficult part of the observation. You will want to have available the position of the object every 15 min. In case you loose it you can go to the next expected position and wait for it to come.
2009 UN3 will be an excellent opportunity for occultationists with integrating video cameras or bigger telescopes to try another area in which amateurs can make a difference. So don't wait but read the video astrometry guide and get ready to observe. And remember for astrometry you need as many stars as you can get in the FOV and the target does not have to be in the center.
The near-Earth object, designated 2010 AB78, was discovered by WISE Jan. 12.
The mission's sophisticated software picked out the moving object against a
background of stationary stars. As WISE circled Earth, scanning the sky above,
it observed the asteroid several times during a period of one-and-a-half days
before the object moved beyond its view. Researchers then used the University
of Hawaii's 2.2-meter (88-inch) visible-light telescope near the summit of
Mauna Kea to follow up and confirm the discovery.
The asteroid is currently about 158 million kilometers (98 million miles) from
Earth. It is estimated to be roughly 1 kilometer (0.6 miles) in diameter and
circles the sun in an elliptical orbit tilted to the
plane of our solar system. The object comes as close to the sun as Earth, but
because of its tilted orbit, it will not pass very close to Earth for many
centuries. This asteroid does not pose any foreseeable
impact threat to Earth, but scientists will continue to monitor it.
Near-Earth objects are asteroids and comets with orbits that pass relatively
close to Earth's path around the sun. In extremely rare cases of an impact, the
objects may cause damage to Earth's surface. An
asteroid about 10 kilometers (6 miles) wide is thought to have plunged into our
planet 65 million years ago, triggering a global disaster and killing off the
dinosaurs.
Additional asteroid and comet detections will continue to come from WISE. The
observations will be automatically sent to the clearinghouse for solar system
bodies, the Minor Planet Center in Cambridge, Mass., for comparison against the
known catalog of solar system objects. A community of professional and amateur
astronomers will provide follow-up observations, establishing firm orbits for
the previously unseen objects.
"This is just the beginning," said Ned Wright, the mission's principal
investigator from UCLA. "We've got a fire hose of data pouring down from
space."
On Jan. 14, the WISE mission began its official survey of the entire sky in
infrared light, one month after it rocketed into a polar orbit around Earth
from Vandenberg Air Force Base in California. By casting a wide net, the
mission will catch all sorts of cosmic objects, from asteroids in our own solar
system to galaxies billions of light-years away. Its data will serve as a
cosmic treasure map, pointing astronomers and telescopes, such as NASA's
Spitzer Space Telescope and the upcoming James Webb Space Telescope, to the
most interesting finds.
WISE
is expected to find about 100,000 previously unknown asteroids in our main
asteroid belt, a rocky ring of debris between the orbits of Mars and Jupiter.
It will also spot hundreds of previously unseen near-Earth objects.
By observing infrared light, WISE will reveal the darkest members of the
near-Earth object population -- those that don't reflect much visible light.
The mission will contribute important information about asteroid and comet
sizes. Visible-light estimates of an asteroid's size can be deceiving, because
a small, light-colored space rock can look the same as a big, dark one. In
infrared, however, a big dark rock will give off more of a thermal, or infrared
glow, and reveal its true size. This size information will give researchers a
better estimate of how often Earth can expect potentially devastating impacts.
"We are thrilled to have found our first new near-Earth object," said
Amy Mainzer of NASA's Jet Propulsion Laboratory in Pasadena, Calif. Mainzer is
the principal investigator of NEOWISE, a program to mine the collected WISE
data for new solar system objects. "Many programs are searching for near-Earth
objects using visible light, but some asteroids are dark, like pavement, and
don't reflect a lot of sunlight. But like a parking lot, the dark objects heat
up and emit infrared light that WISE can see."
"It is great to receive the first of many anticipated near-Earth object
discoveries by the WISE system," said Don Yeomans, manager of NASA's
Near-Earth Object Program Office at JPL. "Analysis of the WISE data will
go a long way toward understanding the true nature of this population."
(This created a certain amount of what
might be called ‘excitement’ on the
A new report from the National Research
Council lays out options NASA could follow to detect more near-Earth
objects (NEOs) -- asteroids and comets that could pose a hazard if they cross
Earth’s orbit. The report says the $4 million the U.S. spends annually to
search for NEOs is insufficient to meet a congressionally mandated requirement
to detect NEOs that could threaten Earth.
Congress mandated in 2005 that NASA discover 90 percent of NEOs whose diameter is 140 meters or greater by 2020, and asked the National Research Council in 2008 to form a committee to determine the optimum approach to doing so. In an interim report released last year, the committee concluded that it was impossible for NASA to meet that goal, since Congress has not appropriated new funds for the survey nor has the administration asked for them.
In its final report, the committee lays out two approaches that would allow NASA to complete its goal soon after the 2020 deadline; the approach chosen would depend on the priority policymakers attach to spotting NEOs. If finishing NASA’s survey as close as possible to the original 2020 deadline is considered most important, a mission using a space-based telescope conducted in concert with observations from a suitable ground-based telescope is the best approach, the report says. If conserving costs is deemed most important, the use of a ground-based telescope only is preferable.
The report also recommends that NASA monitor for smaller objects -- those down to 30 to 50 meters in diameter -- which recent research suggests can be highly destructive. However, the report stresses that searching for smaller objects should not interfere with first fulfilling the mandate from Congress. Beyond completion of that mandate, the report notes the need for constant vigilance in monitoring the skies, so as to detect all dangerous NEOs. In addition, the nation should undertake a peer-reviewed research program to better investigate the many unknown aspects connected with detecting NEOs and countering those that could be a threat. The U.S. should also take the lead in organizing an international entity to develop a detailed plan for dealing with hazards from these objects.
In addition, the report recommends that immediate action be taken to ensure the continued operation of the Arecibo Observatory in Puerto Rico. NASA and NSF should support a vigorous program of NEO observations at Arecibo, and NASA should also support such a program at the Goldstone Deep Space Communications Complex. Although these facilities cannot discover NEOs, they play an important role in accurately determining the orbits and characterizing the properties of NEOs within radar range.
The Scope of the Hazard
Near-Earth objects are asteroids and comets that orbit the Sun and approach or cross Earth’s orbit. An asteroid or comet about 10 kilometers in diameter struck the Yucatan peninsula 65 million years ago and caused global devastation, probably wiping out large numbers of plant and animal species including the dinosaurs. Objects as large as this one strike Earth only about once every 100 million years on average, the report notes. NASA has been highly successful at detecting and tracking objects 1 kilometer in diameter or larger, and continues to search for these large objects. Objects down to sizes of about 140 meters in diameter -- which NASA has been mandated to survey for -- would cause regional damage; such impacts happen on average every 30,000 years, the report says.
While impacts by large NEOs are rare, a single impact could inflict extreme damage, raising the classic problem of how to confront a possibility that is both very rare and very important. Far more likely are those impacts that cause only moderate damage and few fatalities. Conducting surveys for NEOs and detailed studies of ways to mitigate collisions is best viewed as a form of insurance, the report says. How much to spend on these insurance premiums is a decision that must be made by the nation’s policymakers.
Mitigating Damage
The report also examines what is known about methods to defend against NEOs. These methods are new and still immature. No single approach is effective for the full range of near-Earth objects, the committee concluded. But with sufficient warning, a suite of four types of mitigation is adequate to meet the threat from all NEOs, except the most energetic ones.
* Civil defense (evacuation, sheltering in place, providing emergency
infrastructure) is a cost-effective mitigation measure for saving lives from the smallest NEO impact events and is a necessary part of mitigation for larger events.
* “Slow push” or “slow pull” methods use a spacecraft to exert force on the target object to gradually change its orbit to avoid collision with the Earth. This technique is practical only for small NEOs (tens of meters to roughly 100 meters in diameter) or possibly for medium-sized objects (hundreds of meters), but would likely require decades of warning. Of the slow push/pull techniques, the gravity tractor appears to be by far the closest to technological readiness.
* Kinetic methods, which fly a spacecraft into the NEO to change its orbit, could defend against moderately sized objects (many hundreds of meters to 1 kilometer in diameter), but also may require decades of warning time.
* Nuclear explosions are the only current, practical means for dealing with large NEOs (diameters greater than 1 kilometer) or as a backup for smaller ones if other methods were to fail.
Although all of these methods are conceptually valid, none is now ready to implement on short notice, the report says. Civil defense and kinetic impactors are probably the closest to readiness, but even these require additional study prior to reliance on them.
Given the significant unknowns about many aspects of the threat and its mitigation, the report recommends that the U.S. start a peer-reviewed, targeted research program on the hazards posed by NEOs, and how to deal with them. Because this is a policy-driven, applied research program, it should not be in competition with basic scientific research programs or be funded from them, the report adds.
The study was sponsored by NASA at the request of Congress. The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council make up the National Academies. They are private, nonprofit institutions that provide science, technology, and health policy advice under a congressional charter. The Research Council is the principal operating agency of the National Academy of Sciences and the National Academy of Engineering. A committee roster follows.
Copies of “Defending Planet Earth: Near-Earth Object Surveys and Hazard Mitigation Strategies” are available from the National Academies Press, telephone +1 202-334-3313 or 1-800-624-6242, or on the Internet at http://www.nap.edu/catalog.php?record_id=12842.
The proposed missions would probe the atmosphere and crust of Venus; return a
piece of a near-Earth asteroid for analysis; or drop a robotic lander into a
basin at the moon's south pole to return lunar
rocks back to Earth for study.
NASA will select one proposal for full development after detailed mission
concept studies are completed and reviewed. The studies begin during 2010, and the selected mission must be
ready for launch no
later than Dec. 30, 2018. Mission cost, excluding the launch vehicle, is
limited to $650 million.
"These are projects that inspire and excite young scientists, engineers
and the public," said Ed Weiler, associate administrator for the Science
Mission Directorate at NASA Headquarters in Washington. "These three
proposals provide the best science value among eight submitted to NASA this
year."
Each proposal team initially will receive approximately $3.3 million in 2010 to
conduct a 12-month mission concept study that focuses on implementation
feasibility, cost, management and technical plans.
Studies also will include plans for educational outreach and small business
opportunities.
The selected proposals are: The Surface and Atmosphere Geochemical Explorer, or
SAGE, mission to Venus would release a probe to descend through the planet's
atmosphere. During descent, instruments would conduct extensive measurements of
the atmosphere's composition and obtain meteorological data. The probe then
would land on the surface of Venus, where its abrading tool would expose both a
weathered and a pristine surface area to measure its composition and
mineralogy. Scientists hope to understand the origin of Venus and why it is so
different from Earth. Larry Esposito of the University of Colorado in Boulder,
is the principal investigator.
The Origins Spectral Interpretation Resource Identification Security Regolith
Explorer spacecraft, called Osiris-Rex, would rendezvous and orbit a primitive
asteroid. After extensive measurements, instruments would collect more than two
ounces of material from the asteriod's surface for return to Earth. The
returned samples would help scientists better understand and answer long-held
questions about the formation of our solar system and the origin of complex
molecules necessary for life. Michael Drake, of the University of Arizona in
Tucson, is the principal investigator.
MoonRise: Lunar South Pole-Aitken Basin Sample Return Mission would place a
lander in a broad basin near the moon's south pole and return approximately two
pounds of lunar materials for study. This region of the lunar surface is
believed to harbor rocks excavated from the moon's mantle. The samples would
provide new insight into the early history of the Earth-moon system. Bradley
Jolliff, of Washington University in St. Louis, is the principal investigator.
The proposals were submitted to NASA on July 31, 2009, in response to the New
Frontiers Program 2009 Announcement of Opportunity. New Frontiers seeks to
explore the solar system with frequent,
medium-class spacecraft missions that will conduct high-quality, focused
scientific investigations designed to enhance understanding of the solar system.
The final selection will become the third mission in the program. New Horizons,
NASA's first New Frontiers mission, launched in 2006, will fly by the
Pluto-Charon system in 2014 then target another Kuiper Belt object for study.
The second mission, called Juno, is designed to orbit Jupiter from pole to pole
for the first time, conducting an in-depth study of the giant planet's
atmosphere and interior. It is
slated for launch in August 2011. For more information about the New Frontiers
Program, visit: http://newfrontiers
Most models of Solar System formation posit that the planets formed from the
collision and eventual coalescence of planetesimals. Beyond the orbit of Mars,
the gravitational perturbation of the giant planet Jupiter prevented the
formation of a planet-sized body by disrupting the orbits of many of these
planetesimals. The remaining bodies, some of them several hundred kilometres in
size, have undergone frequent collisions since this time and today mostly
occupy the asteroid belt between the orbits of Mars and Jupiter. Asteroids are
of interest for understanding the formation process of our Solar System because
they carry information about the nature and composition of the Solar System at
an early stage of its formation. Asteroid (2867) Steins, an E-type asteroid, is
a rare type of solar system body. Only a few tens of these asteroids have been
detected.
In the results published in the 8 January issue of Science, H. Uwe Keller and
colleagues report on observations of asteroid Steins obtained during the
Rosetta flyby of 5 September 2008. This is the first time
that a close-up view of an E-type asteroid has been obtained. The closest
approach to the asteroid was at 18:38:20 UTC at a distance of 803 km. About 60
per cent of the surface was resolved during the flyby providing a unique set of
images from which a number of important physical properties can be inferred.
Little was known about asteroid (2867) Steins when it was chosen early in 2004
as one of the targets for a close flyby during the Rosetta mission. At the
time, it was classified as an E-type asteroid on the
basis of its visual and near-infrared spectrum and its high albedo. Later,
ground-based observations estimated a diameter of approximately 4.6 km and
determined a rotation period of about 6 hours.
The new OSIRIS images show Steins to be an oblate body, resembling a brilliant
cut diamond, with dimensions of 6.67x 5.81 x 4.47 km³. Its surface is mostly
covered with shallow craters with some of the larger craters being pitted with
smaller ones. Analysis of the impact craters reveals a deficit of small craters
(those with diameter less than 0.5 km) which Keller and his colleagues attribute
to surface reshaping as a result of the Yarkovsky-O'
Two remarkable features are clearly visible in the images obtained near closest
approach: a large, 2.1 km diameter crater located at the south pole, and a
chain of pits which extend northwards from this crater. Taken together these
features suggest that Steins was subject to a big impact which created the
large crater and caused fracturing of the asteroid body resulting in it having
a rubble pile structure. This type of loosely-bound structure is also
consistent with the YORP effect hypothesis.
Detailed study of the OSIRIS images has also allowed Keller and his colleagues
to confirm the nature of Steins as an E-type asteroid – the albedo and spectral
characteristics are consistent with this
classification - and to demonstrate that there is no measurable surface colour
variation, which points to a homogeneous composition.
The view of Steins obtained by OSIRIS during the September 2008 flyby with
Rosetta has provided scientists with the first detailed characterisation of
this rare type of solar system body.
The results are reported in "E-type asteroid (2867) Steins as Imaged by
OSIRIS on board Rosetta" by H. U. Keller, C. Barbieri, D. Koschny, P.
Lamy, H. Rickman, R. Rodrigo, H. Sierks, M. F. A’Hearn, F. Angrilli, M. A.
Barucci, J.-L. Bertaux, G. Cremonese, V. Da Deppo, B. Davidsson, M. De Cecco,
S. Debei, S. Fornasier, M. Fulle, O. Groussin, P. J. Gutierrez, S. F. Hviid,
W.-H. Ip, L. Jorda, J. Knollenberg, J. R. Kramm, E. Kührt, M. Küppers, L.-M.
Lara, M. Lazzarin, J. Lopez Moreno, F. Marzari, H. Michalik, G. Naletto, L.
Sabau, N. Thomas, K.-P. Wenzel, I. Bertini, S. Besse, F. Ferri, M. Kaasalainen,
S. Lowry, S. Marchi, S. Mottola, W. Sabolo, S. E. SchrÃder, S. Spjuth, and P.
Vernazza, Science, Vol. 327. no. 5962, pp. 190 – 193, 8 January 2010. DOI:
10.1126/science.
Footnote: The YORP effect is a phenomenon that occurs when photons from the Sun
are absorbed by a body and reradiated as infrared emission which carries off
momentum as well as heat. The loss of momentum causes a change in the rotation
rate of a small body such as an asteroid. The resulting high spin rate of
asteroid Steins could have caused material to migrate towards the equator of
the asteroid resulting in the distinctive conical shape.
better) the accuracy of UCAC3 is generally either better than, or the same as,
UCAC2.
There are a number of very puzzling meteoritic events including (a) The
Tunguska event. It is the only known example of a low altitude atmospheric
explosion. It is also the largest recorded event. Remarkably no fragments or
significant chemical traces have ever been recovered.(b) Anomalous low altitude
fireballs which (in some cases) have been observed to hit the ground.
The absence of fragments is
particularly striking in these cases, but this is not the only reason they are
anomalous. On the other hand, there is strong evidence that most of our galaxy
is made
from exotic dark material - `dark matter'. Mirror matter is one well motivated
dark matter candidate, since it is dark and stable and it is required to exist
if particle interactions are mirror symmetric.
If mirror matter is the dark matter, then some amount must exist in our solar
system. We demonstrate that the mirror matter theory allows for a simple
explanation for the puzzling meteoritic events [both (a) and (b)] if they are
due to mirror matter space-bodies. A direct consequence of this explanation is
that mirror matter fragments should exist in (or on) the ground at various
impact sites. The properties of this potentially recoverable material depend importantly
on the sign of the photon-mirror photon kinetic mixing parameter,
"epsilon". We argue that the broad characteristics of the anomalous
events suggests that "epsilon" is probably negative. Strategies for
detecting mirror matter in the ground are discussed.
There are several papers that have been submitted and accepted, but not included in this issue for reasons of space. I urge anyone who has responsibility for drafting papers for the JDSO to do the
drafting sooner rather than later, to avoid lengthy delays until actual publication of the paper.
http://www.cfa.
though, as I am currently moving all my software to a new PC, and it will take
me some time before everything is up and running.
The default for stacked images will certainly be 'K', but if the observer decides that any other flag is
more important in a particular case, he or she can change that flag.
Personally, I see no problem with flagging stacked images. A lot of people do
excellent work using stacked images, and I see no reason why that flag will
depreciate their work. In case that there is some problem with an observation,
it might be useful to know that it came from a stack.
The ultimate solution would probably be the new MPC format. That would allow
for multiple flags, and additional information (
observation than a simple flag.
http://www.cfa.
Aborigines sometimes made up new stories when talking to researchers to fit
their expectations. In particular I was told that the *real* dreamtime stories
about impact craters usually don't have cosmic connections whatsoever, e.g. in
one case (Wolf Creek?) the story is that a giant snake came out of the ground,
causing the hole with the raised rim. There were signs at Gosses Bluff back
then telling
alleged dreamtime stories that do include an impact, but in the light of that
geologist's experience that may be doubtful. Actual literature references on
that complex would be appreciated, actually. Image at;
http://pasj.
Websites which might be of interest
OrbitViewer
– added to Links page under ‘Asteroids in general’
ARPS Website updates
Updated pages
Asteroid news
Index
January 2010 Observations
Links
Meetings
News archive
Observations received
Site guide
Space missions
Table of contents
New pages
The rotation period of asteroid
(4080) Galinskij - short paper published in the December 2009 issue of the BAA
Journal
The News archive can be accessed here
This is my last update of the web site
as I have decided to relinquish the post of Web Site Manager and concentrate on
observing comets. My thanks to all who have contributed observations, images
and other material.
Web Site
Manager,
Email; roger.dymock(at)ntlworld.com (please replace (at) with @)