The central disk of our Milky Way galaxy with the Gemini stellar stream highlighted in the top right of the image. Credit: Andrew Drake/Axel Mellinger

A stream of at least 150 ancient variable stars has been confirmed to extend some 130,000 light years beyond our own galaxy’s stellar halo — on the fringes of the Intergalactic Medium, where aside from hot gas and dark matter, space-time becomes as sparse as the deep Sahara. The confirmation, based on analysis of 10 billion year-old dying RR Lyrae stars in the Gemini constellation, was done by an international team of astronomers, including CACR scientist Andrew Drake, who report their findings in The Astrophysical Journal.

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Wednesday December 7, 2011
9:00AM – 12:00PM
Location: Hameetman Auditorium, Cahill Center for Astronomy and Astrophysics, California Institute of Technology

The Virtual Observatory (VO) is realizing global electronic integration of astronomy data, tools, and services for use by individuals around the world. This new environment of interoperability will facilitate astronomy research with a speed, efficiency, and effectiveness not previously possible, and it will be available to all researchers, independent of their affiliation or access to observing facilities.

During this “VO Day”, aimed at research astronomers, VO experts from the Virtual Astronomical Observatory (VAO) – one of many VO projects worldwide – will demonstrate new tools and services for data-intensive astronomy in the context of a range of science use cases and tutorials. These use cases and tutorials, based on recent results from the literature and on-going missions, will include:

• constructing and modeling spectral energy distributions
• cross-matching objects from diverse catalogs
• exploration of time series data
• image analysis tools.

This workshop is organized and sponsored by the US Virtual Astronomical Observatory. The workshop is open to anyone interested, and there is no registration fee. Registration, however, is required – Please visit the websites for registration and further information, including maps & directions.

VAODay@LA: http://www.usvao.org/voday@la

“Looking for Nuggets in Massive Data Streams”
Tuesday, June 7, 2011
9:00am – 12:30pm
Hameetman Auditorium, Cahill Building

This short course is being held in conjunction with the KISS study “Digging Deeper: Algorithms for Computationally-Limited Searches in Astronomy.”

This series of talks will review some of the tools and techniques used for detection and classification on transient signals in massive data streams in astronomy, e.g., searches for gravitational wave sources, or transient events in synoptic sky surveys.  The focus of this short course is on advanced data mining and statistical techniques and algorithms.

Speakers include:

09:15 – 10:15  Signal analysis and parameter estimation in gravitational wave astronomy, Badri Krishnan (AEI)
10:15 – 10:45  Keynote talk:  New Developments in Time Series Analysis, Jeff Scargle (NASA Ames)
10:45 – 11:15  Coffee break
11:15 – 11:45  Automated Classification of Transients, Ashish Mahabal (Caltech)
11:45 – 12:15  Machine Learning applications in Time Domain Astronomy, Pavlos Protopapas (CfA)

The short course will be videotaped and made available on the KISS website within two weeks after the workshop is completed.

Seating is limited and is available on a first come, first served basis – and no registration is required. An informal lunch is provided for all short course attendees.

Please see http://www.kiss.caltech.edu for more details.

Andrew Drake, computational scientist, Caltech Center for Advanced Computing Research

The Catalina Real-time Transient Survey (CRTS) is a Caltech operated optical transient survey that covers most of the Northern and Southern sky in search of transient astrophysical phenomena occurring on timescales of minutes to years. The project uses data from the Catalina Sky Survey NEO search and began real-time discovery and publication of transient events in November 2007. CRTS has found thousands of sources ranging from UV Ceti and dwarf nova outbursts to supernovae and Blazars. I will discuss the survey, the discoveries made to date, and our efforts to provide immediate open access to CRTS discoveries and historical CSS data.

* For further information: contact Gina Armas gina@its.caltech.edu phone: 4671
For the full scoop, see event web page: http://www.astro.caltech.edu/~gma/colloquia.html.
* Sponsored by: Physics, Math and Astronomy

A Universe of Astronomical Data

“After a decade of developing the tools and infrastructure needed to get these databases to talk to each other, the project, now called the Virtual Astronomical Observatory and funded by NASA and the NSF, opened for business in May. “We’re moving onto the operational phase,” says [Matthew] Graham, a member of the program council of the VAO. “The hope is that we can really make an impact on the community.” In addition to Graham, CACR computational scientist Roy Williams also plays a leading role with the VAO.”

Rendering of a rapidly spinning, gravitational-wave emitting newborn neutron star. Simulation: Ott et al. 2007 Rendering: Ralf Kaehler ZIB/AEI/KIPAC 2007

This month CACR has installed and configured a new cluster in the Powell-Booth Laboratory for Computational Science. This system is specifically configured to meet the applications needs of Caltech’s Theoretical AstroPhysics Including Relativity (TAPIR) group in the Physics, Mathematics, and Astronomy Division.

The MRI2 cluster is funded by an NSF MRI-R2 award with matching funds from the Sherman Fairchild Foundation.The configuration, integrated by Hewlett-Packard and CACR’s operations team, consists of 1536 Intel X5650 compute cores in 128 dual Westmere hex-core nodes equipped with a total of ~3 TB of memory, connected via QDR InfiniBand (IB). It includes 100 TB of high-performance, high-reliability disk space access via IB through a Panasas rack.

The research project using the new cluster, Simulating eXtreme Spacetimes: Facilitating LIGO and Enabling Multi-Messenger Astronomy, is led by Professor Christian Ott. The co-Investigators on the MRI award are Dr. Mark Scheel of TAPIR and CACR’s director, Dr. Mark Stalzer. The research will explore the dynamics of spacetime curvature, matter, and radiation at high energies and densities. Central project aspects are the simulation of black hole binary coalescence, neutron-star — black hole inspiral and merger, and the collapse of massive stars leading to core-collapse supernovae or gamma-ray bursts. Key results will be the prediction of gravitational waveforms from these phenomena to enable LIGO gravitational wave searches and to facilitate the extraction of (astro-)physics from observed signals.

The MRI2 cluster is named Zwicky, in honor of Caltech Astrophysics Professor Fritz Zwicky (1898-1974), who discovered supernovae and who was the first to explain how supernovae can be powered by the collapse of a massive star into a neutron star. Zwicky also discovered the first evidence for dark matter in our universe, proposed to use supernovae as standard candles to measure distances in the universe, and suggested that galaxy clusters could act as gravitational lenses.

Download the new Transient Events Application at the iTunes Store!

The heavens are much more dynamic than most people realize. Every night stars and galaxies vary in brightness and comets move through our solar system. The astronomy community has survey telescopes monitoring the sky on a regular basis looking for objects which vary in brightness or position in the night sky. The images from these telescopes are analyzed automatically and variable objects are published through CACR’s Skyalert system. Transient Events currently receives events from CACR’s Catalina Real-Time Survey (CRTS), with more surveys to be added in the future. Transient Events provides an easy-to-use application to monitor these events. (Read more about the features of the Transient Events iPhone App)

The real-time event discovery, processing, and dissemination of events is made possible by NASA under grant NNG05GF22G, and by the NSF under grants AST-0909182 (CRTS) and OCI-0915473 (Skyalert). Creation of the Transient Events application was funded by the the Large Synoptic Survey Telescope (LSST).

The stream will be broadcast live at http://twitter.com/skyalert with the tag #SantaAlert, at http://skyalert.org/santa, and also through the Skyalert page on Facebook. Tell your friends!

SkyAlert collects and distributes reports of astronomical transients in near-real time. When looking deeply and frequently, the sky is full of explosions and movement. Examples of such transients include Supernovae, Cataclysmic Variables, Gamma-ray Bursts, and Blazar Eruption, and the discovery rate of such transients is increasing rapidly as new surveys come online. For further information about Skyalert visit http://www.skyalert.org.

Skyalert delivers events in real time via email, Twitter, instant message, and other protocols to observatories that can do rapid follow-up — some completely automatically with no human in the loop. Other event-driven actions can include fetching data to build a data portfolio, and running machine-learning algorithms and classification rules to make better automatic decisions. The intention is for automated systems to make real-time intelligent decisions. Skyalert uses an international standard, VOEvent, enabling participation in the global event infrastructure, exchanging events with other event brokers, such as NASA’s GCN.

A bright supernova discovered by CRTS within the interacting Antennae galaxies. Click for larger images.

CACR is pleased to announce that an award of $890,000 from the National Science Foundation Astronomy & Astrophysics Research Grants Program was made to the Catalina Real-Time Transient Survey (CRTS) project. The CRTS is based on the special processing and analysis of a data stream from the ongoing NASA-funded Catalina Sky Survey (CSS), which is cataloging near-earth objects and potential planetary hazard asteroids.  The CRTS leverages this existing data stream to discover and study objects and phenomena outside the solar system, opening a new discovery space for time-domain astrophysics at a greatly reduced cost. This project will provide a steady open stream of astronomical events, available to the entire community in real-time. This will be the first and only fully open synoptic sky survey data and event stream.

Exploration of the time domain – discovery and study of objects and phenomena changing on time scales ranging from seconds to years – is now one of the most exciting and rapidly growing fields of astronomy, touching on a broad and diverse spectrum of research areas, from the solar system and discoveries of extra-solar planets to the distant quasars, and from stellar astrophysics to cosmology and extreme relativistic astrophysics. Time domain information is essential for understanding some of the most interesting phenomena we observe. For example, we could not learn anything from a single picture of a supernova, or a single snapshot of a gamma-ray burst: the variability of stars aids to our understanding of their structure and evolution, motions of stars tell us about the structure of our galaxy, and so on.

The CRTS project is already making significant scientific discoveries. For example, CRTS recently found the most energetic supernova ever seen. This event appears to be an example of an extremely rare pair-instabilty supernova. The survey will aid the entire astronomical community in developing new scientific strategies and procedures in the area of large synoptic sky surveys, and develop further and exercise time-domain astronomy cyber-infrastructure within existing Virtual Observatory (VO) environment and framework.

Representing CACR’s expertise in time-domain astronomy, research scientist Andrew Drake created and manages the process for real-time data filtering and analysis, mining through the CSS data for astrophysical transients. Scientific areas of interest include beamed active galactic nuclei (blazars), unusual types of supernovae, fast transients, and an organized serendipitous approach to the discovery of new types of objects and phenomena. More information about the project can be found on the CRTS website.