65 research outputs found
The Thousand Asteroid Light Curve Survey
We present the results of our Thousand Asteroid Light Curve Survey (TALCS)
conducted with the Canada-France-Hawaii Telescope in September 2006. Our
untargeted survey detected 828 Main Belt asteroids to a limiting magnitude of
g'~22.5 corresponding to a diameter range of 0.4 km <= D <= 10 km. Of these,
278 objects had photometry of sufficient quality to perform rotation period
fits. We debiased the observations and light curve fitting process to determine
the true distribution of rotation periods and light curve amplitudes of Main
Belt asteroids. We confirm a previously reported excess in the fraction of fast
rotators but find a much larger excess of slow rotating asteroids (~15% of our
sample). A few percent of objects in the TALCS size range have large light
curve amplitudes of ~1 mag. Fits to the debiased distribution of light curve
amplitudes indicate that the distribution of triaxial ellipsoid asteroid shapes
is proportional to the square of the axis-ratio, (b/a)^2, and may be bi-modal.
Finally, we find six objects with rotation periods that may be less than 2
hours with diameters between 400 m and 1.5 km, well above the break-up limit
for a gravitationally-bound aggregate. Our debiased data indicate that this
population represents <4% of the Main Belt in the 1-10 km size range.Comment: Accepted to Icarus. Full tables to appear there in electronic format,
or contact autho
The Transient Jupiter Trojan-Like Orbit of P/2019 LD2 (ATLAS)
Comet P/2019 LD2 has orbital elements currently resembling those of a Jupiter
Trojan, and therefore superficially appears to represent a unique opportunity
to study the volatile content and active behavior of a member of this
population for the first time. However, numerical integrations show that it was
previously a Centaur before reaching its current Jupiter Trojan-like orbit in
2018 July, and is expected to return to being a Centaur in 2028 February,
before eventually becoming a Jupiter-family comet in 2063 February. The case of
P/2019 LD2 highlights the need for mechanisms to quickly and reliably
dynamically classify small solar system bodies discovered in current and
upcoming wide-field surveys.Comment: 7 pages, 3 figures. Accepted for publication in Icaru
ATLAS-TEIDE: The next generations of ATLAS units for the Teide Observatory
In this work we present the design of the ATLAS unit (Asteroid
Terrestrial-impact Last Alert System) that will be installed at Teide
Observatory in Tenerife island (Spain). ATLAS-Teide will be built by the
Instituto de Astrofisica de Canarias (IAC) and will be operated as part of the
ATLAS network in the framework of an operation and science exploitation
agreement between the IAC and the ATLAS team at University of Hawaii.
ATLAS-Teide will be the first ATLAS unit based on commercial on the shelf
(COTS) components. Its design is modular, each module (building block) consist
of four Celestron RASA 11 telescopes that point to the same sky field, equipped
with QHY600PRO CMOS cameras on an equatorial Direct Drive mount. Each module is
equivalent to a 56cm effective diameter telescope and provides a 7.3 deg^2
field of view and a 1.26 arcsec/pix plate scale. ATLAS-Teide will consist of
four ATLAS modules in a roll-off roof building. This configuration allows to
cover the same sky area of the actual ATLAS telescopes.
The first ATLAS module was installed in November 2022 in an existing
clamshell at the TO. This module (ATLAS-P) is being used as a prototype to test
the system capabilities, develop the needed software (control, image
processing, etc.) and complete the fully integration of ATLAS-Teide in the
ATLAS network. The preliminary results of the tests are presented here, and the
benefits of the new ATLAS design are discussed.Comment: 5 pages, 8 figures, Conference pape
Detection of Earth-impacting asteroids with the next generation all-sky surveys
We have performed a simulation of a next generation sky survey's (Pan-STARRS
1) efficiency for detecting Earth-impacting asteroids. The steady-state
sky-plane distribution of the impactors long before impact is concentrated
towards small solar elongations (Chesley and Spahr, 2004) but we find that
there is interesting and potentially exploitable behavior in the sky-plane
distribution in the months leading up to impact. The next generation surveys
will find most of the dangerous impactors (>140m diameter) during their
decade-long survey missions though there is the potential to miss difficult
objects with long synodic periods appearing in the direction of the Sun, as
well as objects with long orbital periods that spend much of their time far
from the Sun and Earth. A space-based platform that can observe close to the
Sun may be needed to identify many of the potential impactors that spend much
of their time interior to the Earth's orbit. The next generation surveys have a
good chance of imaging a bolide like 2008TC3 before it enters the atmosphere
but the difficulty will lie in obtaining enough images in advance of impact to
allow an accurate pre-impact orbit to be computed.Comment: 47 pages, 16 figures, 2 table
A First Catalog of Variable Stars Measured by the Asteroid Terrestrial-impact Last Alert System (ATLAS)
The Asteroid Terrestrial-impact Last Alert System (ATLAS) carries out its
primary planetary defense mission by surveying about 13000 deg^2 at least four
times per night. The resulting data set is useful for the discovery of variable
stars to a magnitude limit fainter than r~18, with amplitudes down to 0.01 mag
for bright objects. Here we present a Data Release One catalog of variable
stars based on analyzing 142 million stars measured at least 100 times in the
first two years of ATLAS operations. Using a Lomb-Scargle periodogram and other
variability metrics, we identify 4.7 million candidate variables which we
analyze in detail. Through Space Telescope Science Institute, we publicly
release lightcurves for all of them, together with a vector of 169
classification features for each star. We do this at the level of unconfirmed
candidate variables in order to provide the community with a large set of
homogeneously analyzed photometry and avoid pre-judging which types of objects
others may find most interesting. We use machine learning to classify the
candidates into fifteen different broad categories based on lightcurve
morphology. About 10% (430,000 stars) pass extensive tests designed to screen
out spurious variability detections: we label these as `probable' variables. Of
these, 230,000 receive specific classifications as eclipsing binaries,
pulsating, Mira-type, or sinusoidal variables: these are the `classified'
variables. New discoveries among the probable variables number more than
300,000, while 150,000 of the classified variables are new, including about
10,000 pulsating variables, 2,000 Mira stars, and 70,000 eclipsing binaries.Comment: Accepted by AJ; gives instructions for querying ATLAS variable star
database; this new version has nicer lightcurve figure
Observational Constraints on the Catastrophic Disruption Rate of Small Main Belt Asteroids
We have calculated 90% confidence limits on the steady-state rate of
catastrophic disruptions of main belt asteroids in terms of the absolute
magnitude at which one catastrophic disruption occurs per year (HCL) as a
function of the post-disruption increase in brightness (delta m) and subsequent
brightness decay rate (tau). The confidence limits were calculated using the
brightest unknown main belt asteroid (V = 18.5) detected with the Pan-STARRS1
(Pan-STARRS1) telescope. We measured the Pan-STARRS1's catastrophic disruption
detection efficiency over a 453-day interval using the Pan-STARRS moving object
processing system (MOPS) and a simple model for the catastrophic disruption
event's photometric behavior in a small aperture centered on the catastrophic
disruption event. Our simplistic catastrophic disruption model suggests that
delta m = 20 mag and 0.01 mag d-1 < tau < 0.1 mag d-1 which would imply that H0
= 28 -- strongly inconsistent with H0,B2005 = 23.26 +/- 0.02 predicted by
Bottke et al. (2005) using purely collisional models. We postulate that the
solution to the discrepancy is that > 99% of main belt catastrophic disruptions
in the size range to which this study was sensitive (100 m) are not
impact-generated, but are instead due to fainter rotational breakups, of which
the recent discoveries of disrupted asteroids P/2013 P5 and P/2013 R3 are
probable examples. We estimate that current and upcoming asteroid surveys may
discover up to 10 catastrophic disruptions/year brighter than V = 18.5.Comment: 61 Pages, 10 Figures, 3 Table
Identification of known objects in solar system surveys
The discovery of new objects in modern wide-field asteroid and comet surveys
can be enhanced by first identifying observations belonging to known solar
system objects. The assignation of new observations to a known object is an
attribution problem that occurs when a least squares orbit already exists for
the object but a separate fit is not possible to just the set of new
observations. In this work we explore the strongly asymmetric attribution
problem in which the existing least squares orbit is very well constrained and
the new data are sparse. We describe an attribution algorithm that introduces
new quality control metrics in the presence of strong biases in the astrometric
residuals. The main biases arise from the stellar catalogs used in the
reduction of asteroid observations and we show that a simple debiasing with
measured regional catalog biases significantly improves the results. We tested
the attribution algorithm using data from the PS1 survey that used the 2MASS
star catalog for the astrometric reduction. We found small but statistically
significant biases in the data of up to 0.1 arcsec that are relevant only when
the observations reach the level of accuracy made possible by instruments like
PS1. The false attribution rate was measured to be < 1/1,000 with a simple
additional condition that can reduce it to zero while the attribution
efficiency is consistent with 100%.Comment: 29 pages, 8 figures, 2 table
- …