Cost-effective Catalina

The Catalina Sky Survey is a NASA-funded effort to identify near-earth objects, or NEOs, whose orbits cross the path of the Earth and are potentially hazardous. We have talked about NASA’s NEO program in a past posting. The Catalina is a relatively small operation responsible for 70 percent of NEO discoveries over the past three years. The survey team recently announced a new $890,000 NSF grant to expand the objectives of the effort to include optical transients whose brightness changes over time. This will be known as the Catalina Real-Time Transient Survey, or CRTS. To date, the CSS has identified over 700 of these objects, including supernovae, cataclysmic variables, and blazars.

From the press release:

The Catalina Real-Time Transient Survey will be the first and only fully public synoptic sky survey, team members say. It’s a bargain-rate boon to astronomers who are trying to figure out how to manage enormous data streams to be delivered by future synoptic sky survey telescopes, such as Pan-STARRS and the LSST, they add.

And quoting from the CRTS website itself:

The Catalina Real-Time Transient Survey is a synoptic astronomical exploration that covers tens of thousands of square degrees of the sky in order discover rare in interesting transient phenomina. The survey utilizes data taken by the three dedicated telescopes of the highly successful Catalina Sky Survey (CSS) NEO project. CRTS detects and openly publishes all transients within minute of observation so that all astronomers may follow ongoing events.

From the CSS website

What is so ground-breaking about this survey is not simply its mission, but also its laudable goal of making all data freely and immediately available to the public; exactly what is necessary to foster interdisciplinary work. Furthermore, the survey will provide a testing ground for technologies being developed for larger-scale surveys such as LSST and Pan-STARRS. Congratulations to the Catalina team for their continued success!

Twitter, AstroTwitter, and SkyAlert

There has been a great deal of interest lately about astronomy and the new media. Internet technologies and modes of communication, including blogging, twitter, facebook, and even virtual worlds such as second life are becoming avenues for interactions between professional astronomers and space scientists and the larger public. (NASA’s martian rovers, Spirit and Opportunity, have over 16,000 followers on twitter!) This topic was a focus of a recent episode of Astronomy Cast, and there are even conferences dedicated to the topic such as .Astronomy | Networked Astronomy and the New Media where a number of the talks from last year’s conference are available for online viewing via streaming video. These efforts take on deeper significance as we enter the coming age of survey astronomy with open access to data archives and opportunities for citizen scientists of varied backgrounds to become part of the process of scientific discovery via direct collaborations. GalaxyZoo is certainly one of the most successful recent endeavors along these lines. It leverages survey data from the Sloan Digital Sky Survey by enlisting the help of thousands of individuals in an effort to classify galaxies to better understand galaxy evolution, discover new types of objects, and address deeper cosmological questions about the large-scale structure of the Universe.

New modes of communication are also in the works. AstroTwitter, is one such proposal under development of Dr. Stuart Lowe at the Jodrell Bank Centre for Astrophysics. As Lowe describes it, AstroTwitter aims “to make it easy for both professional and amateur telescopes to let the world know what they are observing in real-time.” By being a twitter-like service dedicated to Astronomy, AstroTwitter will overcome some of the inherent limitations of Twitter by providing specialized output formats (Webpages, XML, Google Sky overlays, and VOEvents, for example.)

With new synoptic survey telescopes due to come online in the coming years, the problem of disseminating information about significant events to the public, scientists, or other robotic instruments becomes a growing concern. SkyAlert aims to address this growing need. One of the key complaints about twitter is that there is no discrimination. So yes, I might be interested in the doings of a particular person (or robotic spacecraft!), but there is no other way to filter the content received. The goal of SkyAlert is to create a general subscription-based service that allows users to define constraints on the events of interest. An example from paper Skyalert: Real-time Astronomy for You and Your Robots: I want Catalina transient events where the Catalina measurement is at least 2 magnitudes brighter than that from the Sloan survey. Each event would have a wiki-based web-page with additional supporting data and allow users to add comments or other annotations.

From Williams, et al. 2008. SkyAlert: Real-time Astronomy for You and Your Robots

Welcome to the New Media…get your telescopes and IPhones ready!

Do Science: HST and the Amateur

The role of the amateur in astronomy is changing, with new opportunities for real scientific contributions. The American Association of Variable Star Observers (AAVSO) and its members have been on the forefront of this trend for decades. The kind letter of thanks, posted today on the AAVSO discussion groups, exemplifies the spirit of collaboration between amateur and professional that is becoming an increasingly important element to astronomical research. Moreover, I believe this trend helps to build grass-roots support for funding in astronomy – a profoundly interesting scientific endeavor whose practical applications are harder to define. My advice to anyone out there young or old interested in learning about astronomy or computers (or both!) – join in! Become a part of the process. Don’t just learn about science. Do science!

Date: Sun, 20 Sep 2009 16:00:19 -0400
From: Ed Smith
Subject: AAVSO! THANK YOU for support of the Hubble’s Cosmic Origins Spectrograph

Dear Dr. Templeton and members of the AAVSO,

I write on behalf of the Cosmic Origins Spectrograph (COS) teams at the Space Telescope Science Institute and the University of Colorado. We send our gratitude for your support of the recent successfully completed Hubble Space Telescope (HST) observations with COS of the Symbiotic Star, AG Draconis. Particular recognition must be given the dedication and many nights of observations made by Gordon Myers.

The observing programs targeting AG Dra were part of the process of verification of the instrument’s on-orbit capabilities.

The COS detectors are subject to permanent damage if exposed to a light source that is “too” bright. Various other requirements for several of our on-orbit checks led to the curious choice of AG Dra as the desired target. As you well know this object has outbursts of as much as 5 magnitudes in the U band, brightening on short time scales and with intermittent repeatability!

Without your frequent observations and rapid analysis providing assurance that the object remained quiescent in the weeks and then days leading up to the HST COS observations, we would not have risked scheduling these observations. Indeed, we remained prepared to halt the observations in the final days and hours if you had reported a sudden brightening.

Thanks to your support, successful measurements made using AG Dra are providing important characterizations of how the instrument is operating on-board Hubble. The “COS/NUV Spectral and Thermal Stability” experiment held the shutter open nearly continuously for ~8 hours with continuous readout of the spectrum. We are measuring the position of the spectra on the detector to characterize the amount and variation of drifts in that position. We expect to relate the changes to such things as the thermally induced expansion and contraction of the Hubble telescope and COS mechanisms as they undergo the day and then night portions of the spacecraft’s orbit.

Characterizations such as these not only verify the proper functioning of the instrument, but enable finely tuned interpretations of things such as temporal variation in the scientific measurements of future programs.

The other two COS programs that targeted AG Dra are titled “COS NUV and COS FUV External Spectroscopic Performance -Part 2″. These programs characterize the spatial profile of spectral lines produced by each of the gratings used with the FUV and the NUV detectors.

The results of these programs will be reported in technical documents available via the web-site at STSCI in the coming months. Your valued contribution will be acknowledged in each relevant publication.
(My emphasis).

Thank you so much for your dedication and hard work in support of a new era of NUV/FUV spectroscopy from the Hubble Telescope with the Cosmic Origins Spectrograph.

-Ed Smith

Research and Instrument Scientist
Space Telescope Science Institute
3700 San Martin Blvd.
Baltimore, MD. 21218

Paper of the Day: Great Surveys of the Universe

Last April, Dr. Steven Myers of the National Radio Astronomy Observatory published a position paper for Astro2010 emphasizing the important role that astronomical surveys play in the next 10 years. The idea of a Great Surveys Program, notes Myers, is inspired by NASA’s Great Observatories program which includes the Hubble Space Telescope, the Compton Gamma-Ray Observatory, the Chandra X-Ray Observatory, and the Spitzer Space Telescope.

And on a deeper level, what makes this emphasis on survey astronomy so interesting and profound is the way resulting discoveries will guide the efforts of existing large-aperture narrow-field observatories performing follow-up studies of newly discovered objects. Among the key objectives of survey astronomy noted by Myers:

1. To serve as probes for narrowing in on key cosmological parameters

2. To study the origin and evolution of galaxies across time and to better understand the large-scale structure of the universe

3.To formulate a complete census of the Milky Way’s local neighborhood across the electromagnetic spectrum.

4. Identifying new classes of stellar objects and contributing to theoretical models of stellar structure and evolution.

5.  Discovery of new exoplanets and improving our understanding of how planets and solar systems form.

6. Discovery of and tracking of transient phenomena including gamma-ray bursts and variable stars.

Myers summarizes a number of the underlying challenges to realizing an effective program for survey astronomy. These include required advances in hardware, data-processing, data-mining, and image analysis, visualization, and simulation.   Myers also stresses the importance of public data access, quality assurance, and data interchange – issues that may not seem particularly sexy, but are fundamental to realizing the full potential of survey astronomy.

See also: The Great Surveys of Astronomy Workshop (November 2008, Santa Fe, NM) for additional papers and presentations.