11 research outputs found
Towards an Automated Classification of Transient Events in Synoptic Sky Surveys
We describe the development of a system for an automated, iterative,
real-time classification of transient events discovered in synoptic sky
surveys. The system under development incorporates a number of Machine Learning
techniques, mostly using Bayesian approaches, due to the sparse nature,
heterogeneity, and variable incompleteness of the available data. The
classifications are improved iteratively as the new measurements are obtained.
One novel feature is the development of an automated follow-up recommendation
engine, that suggest those measurements that would be the most advantageous in
terms of resolving classification ambiguities and/or characterization of the
astrophysically most interesting objects, given a set of available follow-up
assets and their cost functions. This illustrates the symbiotic relationship of
astronomy and applied computer science through the emerging discipline of
AstroInformatics.Comment: Invited paper, 15 pages, to appear in Statistical Analysis and Data
Mining (ASA journal), ref. proc. CIDU 2011 conf., eds. A. Srivasatva & N.
Chawla, in press (2011
Connecting the time domain community with the Virtual Astronomical Observatory
The time domain has been identified as one of the most important areas of
astronomical research for the next decade. The Virtual Observatory is in the
vanguard with dedicated tools and services that enable and facilitate the
discovery, dissemination and analysis of time domain data. These range in scope
from rapid notifications of time-critical astronomical transients to annotating
long-term variables with the latest modeling results. In this paper, we will
review the prior art in these areas and focus on the capabilities that the VAO
is bringing to bear in support of time domain science. In particular, we will
focus on the issues involved with the heterogeneous collections of (ancillary)
data associated with astronomical transients, and the time series
characterization and classification tools required by the next generation of
sky surveys, such as LSST and SKA.Comment: Submitted to Proceedings of SPIE Observatory Operations: Strategies,
Processes and Systems IV, Amsterdam, 2012 July 2-
Online classification for time-domain astronomy
The advent of synoptic sky surveys has spurred the development of techniques
for real-time classification of astronomical sources in order to ensure timely
follow-up with appropriate instruments. Previous work has focused on algorithm
selection or improved light curve representations, and naively convert light
curves into structured feature sets without regard for the time span or phase
of the light curves. In this paper, we highlight the violation of a fundamental
machine learning assumption that occurs when archival light curves with long
observational time spans are used to train classifiers that are applied to
light curves with fewer observations. We propose two solutions to deal with the
mismatch in the time spans of training and test light curves. The first is the
use of classifier committees where each classifier is trained on light curves
of different observational time spans. Only the committee member whose training
set matches the test light curve time span is invoked for classification. The
second solution uses hierarchical classifiers that are able to predict source
types both individually and by sub-group, so that the user can trade-off an
earlier, more robust classification with classification granularity. We test
both methods using light curves from the MACHO survey, and demonstrate their
usefulness in improving performance over similar methods that naively train on
all available archival data.Comment: Astroinformatics workshop, IEEE International Conference on Data
Mining 201
Automated Real-Time Classification and Decision Making in Massive Data Streams from Synoptic Sky Surveys
The nature of scientific and technological data collection is evolving
rapidly: data volumes and rates grow exponentially, with increasing complexity
and information content, and there has been a transition from static data sets
to data streams that must be analyzed in real time. Interesting or anomalous
phenomena must be quickly characterized and followed up with additional
measurements via optimal deployment of limited assets. Modern astronomy
presents a variety of such phenomena in the form of transient events in digital
synoptic sky surveys, including cosmic explosions (supernovae, gamma ray
bursts), relativistic phenomena (black hole formation, jets), potentially
hazardous asteroids, etc. We have been developing a set of machine learning
tools to detect, classify and plan a response to transient events for astronomy
applications, using the Catalina Real-time Transient Survey (CRTS) as a
scientific and methodological testbed. The ability to respond rapidly to the
potentially most interesting events is a key bottleneck that limits the
scientific returns from the current and anticipated synoptic sky surveys.
Similar challenge arise in other contexts, from environmental monitoring using
sensor networks to autonomous spacecraft systems. Given the exponential growth
of data rates, and the time-critical response, we need a fully automated and
robust approach. We describe the results obtained to date, and the possible
future developments.Comment: 8 pages, IEEE conference format, to appear in the refereed
proceedings of the IEEE e-Science 2014 conf., eds. C. Medeiros et al., IEEE,
in press (2014). arXiv admin note: substantial text overlap with
arXiv:1209.1681, arXiv:1110.465
Data challenges of time domain astronomy
Astronomy has been at the forefront of the development of the techniques and
methodologies of data intensive science for over a decade with large sky
surveys and distributed efforts such as the Virtual Observatory. However, it
faces a new data deluge with the next generation of synoptic sky surveys which
are opening up the time domain for discovery and exploration. This brings both
new scientific opportunities and fresh challenges, in terms of data rates from
robotic telescopes and exponential complexity in linked data, but also for data
mining algorithms used in classification and decision making. In this paper, we
describe how an informatics-based approach-part of the so-called "fourth
paradigm" of scientific discovery-is emerging to deal with these. We review our
experiences with the Palomar-Quest and Catalina Real-Time Transient Sky
Surveys; in particular, addressing the issue of the heterogeneity of data
associated with transient astronomical events (and other sensor networks) and
how to manage and analyze it.Comment: 15 pages, 3 figures, to appear in special issue of Distributed and
Parallel Databases on Data Intensive eScienc
Sources of Gravitational Waves: Theory and Observations
Gravitational-wave astronomy will soon become a new tool for observing the Universe. Detecting and interpreting gravitational waves will require deep theoretical insights into astronomical sources. The past three decades have seen remarkable progress in analytical and numerical computations of the source dynamics, development of search algorithms and analysis of data from detectors with unprecedented sensitivity. This Chapter is devoted to examine the advances and future challenges in understanding the dynamics of binary and isolated compact-object systems, expected cosmological sources, their amplitudes and rates, and highlights of results from gravitational-wave observations. All of this is a testament to the readiness of the community to open a new window for observing the cosmos, a century after gravitational waves were first predicted by Albert Einstein