| Abstracts |
| CLOSE ENCOUNTERS BETWEEN NEAs AND THE EARTH Giovanni B. Valsecchi
IASF-CNR, Istituto di Astrofisica
Spaziale e Fisica Cosmica Some recent advances in the theory of close encounters between small bodies and the Earth are described, with particular emphasis on the phenomenon of resonant returns. In this last case, the theory allows to understand the basic geometrical features of the phenomenon, and to compute the location, size and shape of impact keyholes; moreover, it allows to quantify the reduction of the impulse needed to deflect a NEA away from a collision course. Some examples will be discussed. ---------------------------------------------------------------------------------------- "VERY SHORT ARC ORBIT DETERMINATION" Andrea Milani
Dipartimento di Matematica
"How to make do with One Night Stands" and "why even a ONS contains useful information" ---------------------------------------------------------------------------------------
THE 2002/2003 APPARITION OF 67P/CHURYUMOV-GERASIMENKO Mark
R. Kidger 67P/Churyumov-Gerasimenko
is the new target of the ROSETTA
mission after the failure of ROSETTA
to meet the strict launch window for
an encounter with 46P/Wirtanen. 67P
is a comparatively recent visitor to
the inner solar system having had
q=4.0AU prior to 1840 and
q>2.75AU until a Jupiter
encounter in 1959. The recent large
downward jumps in perihelion
distance are almost certainly the
drivers of 67P/Churyumov-Gerasimenko's
high level of activity. The light
curve, photometric evolution and
morphology of the comet during the
2002/2003 apparition are studied
through the observations of the
Spanish language (although
international) "Observadores_cometas"
group. --------------------------------------------------------------------------------------
153P/IKEYA-ZHANG AND THE COMET OF
HEVELIUS
Mark
R. Kidger Instituto
de Astrofísica de Canarias The
apparition of 153P/Ikeya-Zhang =
C/2002 C1 (Ikeya-Zhang) has been one
of the most important cometary
apparitions of recent years. For the
first time a comet with a period
greater than 156 years has been
observed at more than one apparition.
Despite the identification of C/1661
C1 with 153P/Ikeya-Zhang there
remains the questions of the
inferred major change in the light
curve between 1661 and 2002 and of
the original preferred
identification with C/1532 R1, which
has a strikingly similar orbit. One
possibility is that C/1532 R1 and
153P are fragments of a single
object that split in the past. A
possible splitting scenario is
examined. The possible
identification of previous
apparitions of 153P in 837 and 1273
is examined critically. It is shown
that if these identifications are
correct, the absolute magnitude of
the comet has faded considerably
with time, although this in itself
may be consistent with an object
that is evolving photometrically
after a major splitting. ------------------------------------------------------------------------------------
AMATEUR CCD PHOTOMETRY OF COMETS:
HOW TO STANDARDISE DATA Mark
R. Kidger Instituto
de Astrofísica de Canarias A
difficulty that observers face when
taking data of comets is how to
standardise their data to make it
compatible with other observers
using different instruments. The
widespread use by amateurs of CCD
cameras of high sensitivity and good
cosmetic quality enormously
increases the possibilities of
photometric coverage of comets given
that photometry is calculated
automatically with astrometric
observations. Although the MPC
database now contains huge amounts
of comet photometry, the lack of any
standard method for taking this data
means that the dispersion in
photometry of a comet in the MPC
database may be as large as 2
magnitudes at a given date even for
magnitudes given as "N".
In this paper we explore a standard
system of photometry that is widely
used by Spanish and Italian
observers based on the USNO A2.0
catalogue and a series of standard
photometric apertures. The
suitability of the USNO catalogue
for photometric work is examined
critically and examples of comet
light curves and coma profiles are
shown. A transformation of USNO A2.0
to the standard Landolt BVR system
is presented. -----------------------------------------------------------------------------------
TRANSFORMATION
OF THE BAKER-NUNN CAMERA OF SAN
FERNANDO
M.
Merino3,
J.Núñez1,3,
J.L. Muiños2,
O.Fors1,3,
F.Belizón2,
M. Vallejo2
and J.M. Codina1 1 Observatori
Fabra. Reial Acadèmia de Ciències
i Arts de Barcelona 2
Real Instituto de la Armada en San
Fernando. 3 Departamento
de Astronomia y Meteorologia.
Universidad de Barcelona.
We present the transformation of
a Baker-Nunn Camera (BNC) for remote
and robotic use with a
large format CCD, and its transfer
to a new site located in Catalan
Pyrenees. This project is a
collaboration between the Fabra
Observatory (Reial Acadèmia de Ciències
i Arts de Barcelona) and the Real
Observatorio de la Armada de San
Fernando (ROA). Once refurbished,
the 50cm f/1 camera will have a
useful FOV of 5ºx5º and will be
controlled via Internet. ------------------------------------------------------------------------------------
REFLECTANCE
SPECTROSCOPY AND THE CHEMICAL AND
PHYSICAL
Jordi
Llorca1,2 1Dept. Química
Inorgànica, Universitat de
Barcelona. 2Institut d’Estudis
Espacials de Catalunya. jordi.llorca@qi.ub.es Asteroids
have become objects of intense
interest for planetary astronomers.
They occupy the transition zone
between the dense, volatile-poor
terrestrial planets and the icy,
gas-rich outer planets and
satellites. Although a thorough
understanding of the nature of
asteroids is very important for
science and because some of them may
be potential impactors, we have not
yet analysed directly any asteroid,
either in
situ or by sample return.
Meteorites represent our best choice
to know the physical and chemical
characteristics of asteroids, but we
do not know to what extent the
information revealed by meteorites
is representative enough. Therefore
we need to obtain additional data
using telescopes on Earth.
Reflectance spectroscopy in the
wavelength range 0.3-1.1 mm constitutes a good approach in
order to obtain the mineralogical
composition of the surface of
asteroids. These data is compared to
the spectral reflectivities of
various types of powdered meteorites
measured in the laboratory in order
to provide a basis for chemical
models and population distribution.
Many different spectral types and
mineral compositions are recognised
among asteroids, but almost 75% of
them appear to be similar to
carbonaceous chondrites (which
represent less than 3% of all
meteorites recovered on Earth!).
They consist of volatile-rich, low-density
materials that probably condensed
directly from the solar nebula at
low temperatures. Another 15% of the
asteroids seem to be composed of
iron- and magnesium-rich silicate
minerals with little dark
carbonaceous material. These
asteroids may never have been melted,
but metamorphic or condensation
temperatures must have reached 850ºC
within relatively shallow layers,
resulting in dense bodies.
Relatively rare asteroids appear to
be composed of solely metal (iron-nickel
alloys), resulting from a molten
state at temperatures exceeding 1400ºC.
Most of the metallic asteroids are
100 to 200 km in diameter and do not
appear to be fragmented like the
other types of asteroids. On the
other hand, Apollo-Amor asteroids
exhibit reflectance spectra similar
to ordinary chondrites (70% of
recovered meteorites), whereas main-belt
asteroids do not. Both experimental
studies of the effect of space
environment on the optical
properties of mineral grains as well
as more refined spectral comparisons
of asteroids with meteorites are
required in order to gain a better
insight into the physical properties
and composition of asteroid types. ---------------------------------------------------------------------------------- "A QUICK LOOK AT SOME NEW STAR CATALOGS" Davidschlag Observatory, Astronomical Society of Linz, Austria
Some new
astrometric star catalogs have
recently become available,
among them the
Guide Star Catalog 2.2 (GSC 2),
the USNO-B1.0, and
the USNO CCD
Astrograph Catalog 2 (UCAC 2).
Both the GSC and the
USNO-B are based
on data collected from scanning
photographic plates
from the Palomar
and Southern Sky Surveys.
Positions in the UCAC,
on the other hand,
are derived from recent CCD
observations, and
proper motions
are calculated from various
earlier epoch data.
A comparison of
the features of these catalogues
is presented, and
results obtained
with these catalogs on a few
sample images are
compared.
----------------------------------------------------------------------------------
COMETS IN A NEW LIGHT: WHAT THEIR
X-RAY EMISSION REVEALS ----------------------------------------------------------------------------------- COMETS: ORIGIN AND EVOLUTION The present contribution reviews our current understanding of the origin, nature and evolution of comets (Brandt, 1990; Voelzke and Matsuura, 1998). It also discusses the evolutionary scenarios that have been proposed so far to explain the observed morphological structures along the cometary plasma tail (Brandt et al., 1999; Brandt and Snow, 2000; Voelzke and Matsuura, 2000; Voelzke, 2002). Comets are the most primitive members of our solar system. Because of their orbits and small size, comets have undergone relatively little processing, unlike larger bodies such as the Moon and the Earth, which have been modified considerably since they formed. This pristine nature of comets is evidenced in their high abundance of volatile compounds. The composition of comets contains a wealth of information on their origin and evolution as well as the origin and evolution of our solar system; hence, they are often referred to as cosmic fossils. Our view of plasma structures in comets was based on the ideas of Biermann (1951) as extended by Alfven (1957) to include the effects of the solar wind magnetic field. The solar wind interacts with bright comets through its magnetic field and the cometary ions which are produced in an extended region around the comet. The field lines away from the comet are unimpeded and thus wrap around the comet to create a magnetic field in a hairpin configuration, i.e., a configuration with lobes of opposite polarity separated by a current sheet. Some part of this total magnetic structure includes the visible plasma tail. Because the comet is an obstacle in a supersonic and super-Alfvenic solar wind, a bow shock was also expected. Despite the sketchiness of many of the details, this picture presented specific tests of the data returned by the flyby spacecraft sent to comets P/Giacobini-Zinner and P/Halley.
-
Alfven, H.: 1957, Tellus
9, 192 pp. ---------------------------------------------------------------------------------------------
LAUNCHING CARA THE COMETARY
ARCHIEVE FOR AMATEUR ASTROMER -----------------------------------------------------------------------------------------------
CURRENT
DEVELOPMENTS OF ASTROMETRIC
SOFTWARE FITSBLINK J.
Skvarč
Črni
Vrh Observatory, Slovenia With
the start of NEO follow-up and
asteroid search program at the
Črni Vrh Observatory in 1997
also a complete set of software
tools used for telescope control,
astrometry and data archiving
started development.
The central part of this
software, fitsblink, began as a
simple software for blinking FITS
images on the Unix and Linux based
computers.
New capabilities were added
as needs arose, especially
automatic matching of the catalog
stars what was not a common
feature at the time.
However, several functions
needed for automatic asteroid
observations were left outside
fitsblink in a form of independent
programs which were joined in a
data processing pipeline using
scripting languages like Perl and
Python.
With the forthcoming new
release of fitsblink, an
integration of functions such as
asteroid movement detection,
automatic image alignment etc, has
started.
In addition, several new
functions are introduced:
image addition and
subtraction, comet photometry,
trail detection, sky gradient
subtraction etc.
All data analysis functions
are also available from the Python
scripting language what allows
simple creation of specialized
data processing procedures
specific to the needs of
individual observers.
NEO SEARCH
EFFORTS: A QUICK OVERVIEW OF
CINEOS AND ESO-LA SILLA POSSIBLE
DETECTION OF CLOSE APPROACHES OF
VERY SMALL NEAR
Juraj Toth,
Leonard Kornos -----------------------------------------------------------------------------------------------
FIRST
RESULTS WITH THE NEW 60-CM ROBOTIC
TELESCOPE AT ČRNI VRH B.
Dintinjana, S. Maticic, H.
Mikuz, J. Skvarc, D. Zgavec Crni
Vrh Observatory, Slovenia
After the telescope
installation in summer 2002, we
had first light on September 2,
2002. Since then, the system has
been in trial operation during
which we optimized it to fully
achieve designed specifications.
We report the results of a
telescope calibration tests which
include pointing and guiding
accuracy, focus stability and
photometric calibrations.
We achieved all-sky
pointing accuracy of 2 arc min
without the implementation of any
corrections or encoders. Using the
software corrections, we achieved
30 arc sec. Unguided exposures of
up to 15 minutes duration are
possible on sky areas where
refraction effects are negligible.
During the January – March 2003
period, we obtained a series of
filtered CCD images of various
deep sky objects and comets,
including C/2002 V1 (NEAT) and
C/2002 Y1 (Juels-Holvorcem). These
results show the telescope superb
imaging performance. -------------------------------------------------------------------------------------- ASTROVIRTEL
AND SEARCH FOR TROJANS OF OUTER
PLANETS
Migliorini
A.1, Magrin S.1,
Marchi S.1, Skvarc
J.2, Barbieri C.1,
Marzari F.1,
Scholl H.3, Albrecht R.4 1
University of Padova,
Here we describe the current
status of an on-going work,
performed in the frame of an
approved ASTROVIRTEL program,
having the aim to detect bodies
orbiting around the Lagragian
points of the outer planets (namely
Saturn, Uranus, Neptune),
analogous to the Jupiter Trojans.
Till now, a large number of images
taken with the WFI of the 2.2 m
telescope of ESO at La Silla has
been examined.
Due to the specific nature
of our search, using archive
images, a special observatory code
I03 was assigned by the Minor
Planet Center. Although still
unsuccessful in respect to outer
Trojans, the search
has already produced many
new asteroids, some with
interesting orbits. -------------------------------------------------------------------------------------- Johnson
V-band Photometry of Minor Planets
based on the Hipparcos
Richard Miles Physical classification of
asteroids would greatly benefit
from an expansion of current
magnitude-phase angle observations
to include many more objects than
to date, and to extend coverage to
small phase angles.
A proposal is put forward
for a CCD observing methodology
which exploits the precision
photometry of the Hipparcos
Catalog to yield accurate Johnson
V-band photometry of asteroids. The approach is to reference CCD
images of asteroids relative to
images of Hipparcos stars,
selected to meet the criteria:
5.0<V<9.5 and
+0.4<(B-V)<+1.0.
Images of both are taken
either with the same camera or,
preferably, using a second CCD
camera attached to a shorter focal
length / small aperture telescope
or lens.
It is recommended that the
CCD camera used has a
‘pseudovisual’ spectral
response similar to the S20
photocathode as used on the
Hipparcos satellite and that it is
used unfiltered. ---------------------------------------------------------------------------------------------------- OPTICAL
DESIGN AND FEATURES OF THE NEW
THREE 60 CMS KLEVTSOV TELESCOPES Avila G.1, Guarro J.2, Sanchez S.2, Nomen J.2
1 European
Southern Observatory, Garching
bei Muenchen, Germany The
OAM (Observatori Astronomic de
Mallorca) in collaboration with
CAOS (Club of Amateurs in Optical
Spectroscopy) has buildt three all
spherical, compact, catadioptrics
of 60 cms aperture telescopes. The
optical design is based in a model
for small apertures by Yuri
Klevtsov.
Given the large apertures and the
requirement for a half degree
field of view, our design requires
an additional coma corrector. This
paper describes the optical design
and present status of the project.
Avila G., Guirao C., Rodriguez J.
European
Southern Observatory, Garching
bei Muenchen, Germany We
present a summary of the spectra of
bright comets obtained with
THE
BRITISH ASTRONOMICAL ASSOCIATION
COMET SECTION Jonathan
Shanklin British
Astronomical Association The
British Astronomical Association (BAA)
has been observing comets since
its inception in 1890 and a formal
comet section was set up in 1891.
Unfortunately all early
records were lost during the
Second World War and the earliest
extant records date from the
1940s. The majority of
observations made since then have
been logged in the standard format
used by the International Comet
Quarterly (ICQ) and are available
in electronic format.
In
total there are over 30,000
observations of some 400 comets,
including returns of 80 periodic
comets.
Observers and observations
come from all the continents.
Detailed reports on the
comets seen each year are
published in the British
Astronomical Association Journal,
and current information is
available on the Comet Section web
page at http://www.ast.cam.ac.uk/~jds
The Section also publishes
a twice yearly newsletter The Comet's Tale. -------------------------------------------------------------------------------------------------- Korado Korlevic Visnjan Observatory --------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------- REVEALING THE
NUCLEUS OF LONG-PERIOD COMETS WITH
CANARICAM Mark
R. Kidger, Fabiola Martín-Luis Instituto
de Astrofísica de Canarias To
date sizes have been measured
directly for only two comets: 1P/Halley
and 19P/Borrelly, both in space
probe encounters. To date the sizes
of non-periodic comet nuclei have
only been inferred from indirect
measurements with large
uncertainties. In the case of C/1995
O1 (Hale-Bopp), for example, the
range of diameters estimated by
different techniques ranges from
under 30km to approximately 130km.
However, the technique of measuring
the albedo through visible and mid-infrared
observations of the inert nucleus
offers the possibility of making
accurate determinations of both
albedo and effective radius. To date
such techniques have not been
applicable because of the lack of
instrumentation of suitable
sensitivity to detect bare nuclei at
large heliocentric distances. This
situation is now changing as various
mid-infrared imagers with high
sensitivity will be available on
large telescopes. In particular,
CanariCam the mid-infrared imager of
the Gran Telescopio CANARIAS, which
is due to start scientific
operations in 2005, is capable of
detecting bare nuclei at very large
heliocentric distances. In the case
of C/1995 O1 (Hale-Bopp) the
estimated flux would be 90mJy at
r=17AU compared to a limiting flux
of 0.9mJy for a 5s
detection in 100s. Thus we could
detect nuclei as small as a third of
the diameter of Hale-Bopp in a few
hours even at 17AU. The mid-infrared
observations can be combined with
visible and near-infrared data from
the telescopes at Teide Observatory
to measure exact albedos and
effective radii for a sample of non-periodic
comets thus permitting for the first
time a statistical study of their
properties. -------------------------------------------------------------------------------------
CANARICAM: A
MULTIMODE MID-INFRARED IMAGING
SPECTROGRAPH FOR THE
GRAN TELESCOPIO
CANARIAS Mark
R. Kidger, Fabiola Martín-Luis Instituto
de Astrofísica de Canarias CanariCam
the mid-infrared imager of the Gran
Telescopio CANARIAS, will have many
applications for the study of solar
system bodies, in particular comets,
NEOs and vulcanism on Io. In
particular, it will offer Spanish
solar system scientists and
planetary geologists a series of
exciting research options that have
previously not been available to
them. We present a brief description
of the instrument and its
applications. --------------------------------------------------------------------------------------
PHOTOMETRY AND
MORPHOLOGY OF 67P/CHURYUMOV-GERASIMENKO
DURING THE
2002/03 APPARITION Fernanda
Artigue Observatorio
de los Molinos, Uruguay Mark
R. Kidger & Fabiola Martín-Luis Instituto
de Astrofísica de Canarias We
report the results of three-colour
photometry of 67P/Churyumov-Gerasimenko
in BVR taken with the 82-cm IAC-80
Telescope at Teide Observatory
(Tenerife) and with the 1-m Jacobus
Kapteyn Telescope at the Roque de
los Muchachos Observatory (La Palma)
during March and April 2003. The
comet showed a strongly condensed
aspect with an almost stellar
nucleus in a more extended coma and
a tail that extends out of the 7.1
arcminute field of the IAC-80
Telescope. We present colour maps of
the coma taken with deep exposures
and an analysis of the coma profile
and morphology. --------------------------------------------------------------------------------------
STUDIES
OF SHORT TERM ROTATIONAL
VARIABILITY IN KUIPER BELT OBJECTS Jose
L. Ortiz, V.
Casanova, A. Sota Instituto
de Astrofísica de Andalucía,
CSIC, Granada, Spain The
study of the rotational
variability in large Trans
Neptunian Objects (TNOs) and
Centaurs is important because it
provides a means of obtainining
valuable information on a number
of basic properties which are
extremely useful for our
understanding of the Kuiper Belt
and for the understanding of the
formation and evolution of the
solar system. Since 2000, long
observing runs devoted to the
study of the photometric
variability of TNOs and Centaurs
are scheduled regularly at Sierra
Nevada Observatory using its 1.5m
telescope equipped with a fast
read-out 1024x1024 CCD camera.
We present a compilation of
recent results on the largest
bodies that have been observed,
and some statistics concerning the
range of variability, which
appears to be larger than that of
the main belt asteroids of similar
large sizes. Since the large
bodies are not collisionally
evolved, this result seems to be
an important feature of the
primordial distribution, which is
different for TNOs when compared
to main belt asteroids. ---------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------
SATURN TROJANS PREDICTOR
|
|
|