ATIONAL ADIO O January 2004 Newsletter Issue 98O January 2004 Newsletter Issue 98 Groundbreaking for...

NATIONAL RADIO ASTRONOMY OBSERVATORY

NewsletterNewsletterO January 2004 Issue 98

Groundbreaking for the ALMA Project

Green Bank Telescope Enhancements

Also in this Issue:

VLBA Spacecraft Navigation Pilot Project

VLBI Using Arecibo

The Many Faces of Hydra A

Hydrogen Cyanide Emission from a Distant Quasar

GBT Discovery of Two Pulsars

ATACAMA LARGE MILLIMETER ARRAY (ALMA)

GREEN BANK

SOCORRO

IN GENERAL

NEW RESULTS

PRESS RELEASE: NOVEMBER 12, 2003

Groundbreaking for the ALMA ProjectDetailed Remarks of SpeakersALMA Science Meeting

The Green Bank Telescope

VLA configuration Schedule: VLA/VLBA ProposalsVLBI Global Network Call for ProposalsVLBA Spacecraft Navigation Pilot ProjectVLBI Using AreciboVLA Calibration Transfer in VLBI ExperimentsLarge VLA ProposalsInterferometry ComputingAntenna Bearing ReplacementsX-Ray and Radio ConnectionsEducation and Public Outreach at NRAO-Socorro

NRAO Archives

The Many Faces of Hydra A: Low FrequencyObservations Reveal the Big Picture

Hydrogen Cyanide Emission from a Distant (z=2.6)Quasar – the Essential Signature of a Starburst

GBT Discovery of Two Binary Millisecond Pulsars in theGlobular Cluster M30

TXCam: The Movie (Part 1)The Most Detailed Picture Yet of an Embedded

High-mass YSO

Despite Appearances, Cosmic Explosions HaveCommon Origin, Astronomers Discover

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TABLE OF CONTENTS

Cover Image: European Southern Observatory (ESO) computer image of the Atacama Large Millimeter Array (ALMA) at sunset. TheAtacama Large Millimeter Array (ALMA) is an international astronomy facility. ALMA is an equal partnership between Europe and NorthAmerica, in cooperation with the Republic of Chile, and is funded in North America by the U.S. National Science Foundation (NSF) incooperation with the National Research Council of Canada (NRC), and in Europe by the European Southern Observatory (ESO) and Spain.ALMA construction and operations are led on behalf of North America by the National Radio Astronomy Observatory (NRAO), which ismanaged byAssociated Universities, Inc. (AUI), and on behalf of Europe by ESO.

The NRAO Graphics Department will be happy to assist you in the production of images for your article as well as for

your research papers. Contact Patricia Smiley ([email protected]) with your request.

If you have an interesting new result obtained using NRAO telescopes that could be featured in this section of the NRAO

Newsletter, please contact Juan Uson at [email protected]. We particularly encourage Ph.D. students to describe their

thesis work.

Editor: Barry Turner ([email protected]); Science Editor: Juan Uson ([email protected]); Assistant Editor: Sheila Marks;

Layout and Design: Patricia Smiley

Groundbreaking for theALMA Project

On November 6, 2003, at the site of thefuture Operations Support Facility (OSF)for ALMA at an altitude of 9600 feet,ground was broken by ALMA DirectorMassimo Tarenghi, NSF Division ofAstronomical Sciences Director Waynevan Citters, and ESO Council PresidentPiet van der Kruit at a ceremony attendedby dozens of distinguished guests. Only alittle more than 30 years after the firstdetection of interstellar CO by the NRAO12 Meter Telescope, construction ofALMA, a telescope capable of detectingthe first CO molecules in the Universe,had begun.

Some 50 special guests in a convoy of 17 vehicles par-ticipated in a site visit on the previous day, the largestcrowd of visitors so far. All remained well during thetrip indicating that the site is quite accessible to theuninitiated when adequate precautions, such as the useof the provided bottled oxygen, are taken.

From around the world and from across Chile, guestsbegan to arrive just before noon on the newly constructedALMA road from Chilean highway 23 between

San Pedro de Atacama and Toconao through the OSFsite to the 16,500 foot Llano de Chajnantor, the siteof the ALMA telescopes. At the OSF, the originalconcept which was developed by Mark Gordon andRobert Brown, guests mingled in the stunning weather,meeting newcomers near a display of the flags of theALMA participant nations. As people approached thesplendid white tent, the center of festivities, membersof the press interviewed the various ALMA principals.Far below, the vista extended for dozens of miles, dom-inated by the great Salar de Atacama stretched alongthe horizon to the village of San Pedro. In the fore-ground, the temporary camps for construction workersand ALMA personnel were already in place. Peeringover the northern horizon, the upper reaches ofLicancabur dominated the skyline. Up the mountain,the new ALMA road wound through the rocky land-scape beside Cerro Negro toward the high site. Slowlyguests made their way toward the tent, samplingrefreshments along the way. Cries of ‘Hola!’ rang out asarriving old friends greeted one another to the soundsof Atacameñan music.

By a quarter past twelve, most had arrived at the tent toseek their assigned tables. Each table had been giventhe name of a Chilean wildflower; a photo marked

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January 2004 ALMA Issue 98

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ATACAMA LARGE MILLIMETER ARRAY (ALMA)

Massimo Tarenghi and Fred Lo with ALMA workers.

Flags of the ALMA participant countries fly beside the new road to the array site,which lies beyond Cerro Negro (background).

each. Thus familiarized with the local flora, guests mettheir tablemates and took their seats. At each place lay amysterious dark felt bag. Projected high above thespeakers was the new ALMA logo—a Southern Crossabove an array of radio telescopes. Event organizersand Masters of Ceremonies Daniel Hofstadt andEduardo Hardy (ESO and AUI/NRAO representativesin Chile, respectively) introduced an array of speakers.

Leading off, ESO Council President Piet Vander Kruitoutlined the scientific promise of ALMA. “We are chil-dren of the Universe. Actually, we are children of theUniverse in a very strict sense. Look at our bodies. Byweight we are made up of about a quarter or so ofhydrogen. The rest is in other chemical elements, ofwhich carbon, nitrogen and oxygen are the major con-tributors. In contrast, the Universe, when it was aboutthree minutes old and sufficiently cool that atomicnuclei could exist, consisted of three-quarters of hydro-gen and one quarter of helium. There was no carbon, no

nitrogen, no oxygen or any other chemical elementexcept a trace of lithium and boron. We now know thatthe chemical elements that make up most of our bodieswere formed by nuclear reactions in heavy stars thatlive for a very short while and blew themselves up assupernovae and release the heavy elements into theinterstellar gas so that new planets and possibly life canbe formed. We are stardust. In spite of progress in thetwentieth century, such as understanding nucleosynthe-sis, there are still fundamental questions left. Someimportant ones among these are the following. Whenand how did galaxies form and in what way did earlystar formation and chemical enrichment take place?How do planets form around young stars? To complete-ly solve all aspects of these and other problems weabsolutely need to be able to observe at millimeter andsub-millimeter wavelengths.”

Building on the theme of international cooperation, theDirector of the Division of Astronomical Sciences of theU. S. National Science Foundation Wayne van Cittersdelivered a message from Rita Colwell, the Director ofNSF. In her message, Dr. Colwell said: “The plateauwhere ALMA’s antennae will rise is one of the moststarkly beautiful places on Earth. It’s not enough for thescientific community to identify an outstanding site forastronomy; we rely also on the generosity and coopera-tion of a willing host. Chile has a long history ofopening regions of exceptional scientific merit to theworld community. The Atacama Large Millimeter Arraywill expand our vision of the universe with ‘eyes’ thatpierce the shrouded mantles of space through whichlight cannot penetrate. ALMA’s 64 radio telescopes willserve as windows through which scientists and thecurious public will ‘see’ back in time and far away, towhere the earliest and most distant galaxies wereforming.” van Citters noted “how far we have come inour understanding, our ambition, our sheer scientificaudacity in less than one professional lifetime.” Fromdebating whether sufficiently bright detail wouldsupport baselines as long as 100 m on fledgling arrays,or whether extragalactic molecules could possibly bebright enough, to the present, he continued, where we“await ALMA’s ability to map molecular gas in the firstgeneration of galaxies; this gas already containselements heavier than hydrogen that were forged in thefirst generations of stars to form, less than a billionyears after the origin of time itself.”


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Dr. Lo addresses the participants in the Groundbreaking ceremony.

Arthur Carty, President of theNational Research Council of Canada,noted that as a chemist by training, hehad “come to appreciate the value ofastronomy not only as a fundamentaland important scientific discipline,but also as a unique vehicle forencouraging national and internationalcooperation and for turning our youngpeople on to science and technology.”

Noting that the date was exactly thefortieth anniversary of the signing ofESO’s first agreement with Chile,ESO Director-General CatherineCesarsky noted “here, on Chilean soil,in the great emptiness of the Atacamadesert and closer to the sky thanground-based astronomers have everbeen, we are now embarking upon anambitious exploration of new andunknown celestial territories. We do so in the service ofscience and society, ultimately for the benefit ofhumanity.”

NRAO Director Fred K. Y. Lo recalled the long roadleading to the ALMA groundbreaking in his remarks.“We are here celebrating the realization of the aspira-tions of many astronomers for more than twenty yearsto build a powerful array that can let us peer into thebeginnings of the Universe, galaxies, stars and planetsand perhaps life itself,” he noted. “There are many peo-ple on the NA side to recognize for bringing ALMA intoreality, but I would like to mention three names. Thefirst is Bob Dickman at the NSF. He has been the cham-pion of ALMA within NSF for many years and continuesto play an important role by serving on the ALMABoard. Second is my predecessor, Paul Vanden Bout.Without his persistence for more than 15 years to getthe MMA, and later ALMA, funded, his genius offorming international alliances, and many other effortsincluding the selection of Chajnantor as a site, wewould not have ALMA today. Last but not least, AUIPresident Riccardo Giaconni. As ESO Director General,he signed the key international agreement withPaul Vanden Bout that led eventually to the BilateralALMA that we are celebrating today. Now that he has

joined the NA side, he is making sure that we do notdeviate from getting ALMA built on time and on budget.”

Intendente Jorge Molina welcomed ALMA to theSecond Region of Chile and made reference to theinterest of the Region in becoming the “astronomyworld capital” now that both the VLT and ALMA arelocated there. He also referred to the impact ALMAwill have on the local community, in particular after thesignature on 28 October of the agreement betweenALMA and the Intendencia that benefits the San PedroCommune.

Mayor of San Pedro de Atacama Sandra Berna echoedIntendente Molina’s remarks, noting that San Pedro wasthe capital of Chilean archaeology and that now it maybecome a capital of science as well. Finally, the Bishopof Calama, Obispo Guillermo Vera Soto, blessing thebeginning of the ALMA construction work, usedbiblical imagery in referring to the astronomical aimsof the project.

A reflection on ALMA science was given by thePresident of AUI, Riccardo Giacconi, winner of the2002 Nobel Prize in Physics. Dr. Giacconi shared hisvision of the scientific significance of ALMA, elaborat-ing on themes of particular interest. “ALMA will have


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Riccardo Giacconi, President of AUI, noted the great scientific promise of ALMA.

unsurpassed sensitivity and imaging capabilities formolecular spectroscopic study of external galaxies andwill be able to detect the first galaxies formed throughtheir dust emission at z > 20. It will be able to studystar formation cores in nearby galaxies and assess therole of morphology and environment in their dynamic

and chemical evolution. The setting ofALMA in the southern hemisphere willpermit detailed studies of the large andsmall magellanic clouds. The study oforganic molecules in interstellar spacewill provide indispensable clues to theorigin of life in the universe”.

Project Director Massimo Tarenghiexpressed the ALMA team’s feelingsabout reaching this milestone. “We mayhave a lot of hard work in front of us,”he said, “but all of us in the team areexcited about this unique project. We areready to work for the internationalastronomical community and to providethem in due time with an outstandinginstrument allowing trailblazing researchprojects in many different fields ofmodern astrophysics.”

After a punctual and successful ceremony many guestsreturned to the task of finishing the construction in asimilarly timely fashion.

H. A. Wootten

Rita R. ColwellDirector, National Science Foundation

The U.S. National Science Foundation joins today withour North American partner Canada, and with theEuropean Southern Observatory, Spain, and Chile toprepare for a spectacular new instrument. The AtacamaLarge Millimeter Array will expand our vision of theuniverse with “eyes” that pierce the shrouded mantlesof space through which light cannot penetrate.

I extend both my congratulations and my regret for notbeing able to join you. As you break ground for a newobservatory, I will join the President at a ceremony torecognize scientists and engineers who have brokenground with far-reaching observations throughout theircareers. They will be receiving the distinguishedNational Medal of Science.

The plateau where ALMA’s antennae will rise is one ofthe most starkly beautiful places on Earth. It’s notenough for the scientific community to identify anoutstanding site for astronomy; we rely also on thegenerosity and cooperation of a willing host. Chile hasa long history of opening regions of exceptional scien-tific merit to the world community.

Last year, I participated in the official opening ofGemini South near La Serena. Gemini is but one in along line of facilities that have taken advantage of theobserving conditions in Chile and paved the way forone more.

Today marks the official start of construction. But theALMA partnership also breaks ground with a novel col-laboration that ensures equal access by astronomers onat least three continents. International partnerships arequickly becoming the norm of the millennium, enabling


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NSF’s Robert Dickman christens a block with Chilean wine as Eduardo Hardy,Fred Lo, Massimo Tarenghi, Catherine Cesarsky and Daniel Hofstadt (l-r) look on.

Detailed Remarks of Speakers

organizations and nations to combine funds to achievegreater scientific capability. NSF is proud to participatein the creation of an instrument that will provideunprecedented power for science and immeasurableknowledge for all.

ALMA’s 64 radio telescopes will serve as windowsthrough which scientists and the curious public will“see” back in time and far away, to where the earliestand most distant galaxies were forming.

Our investments in ALMA’s educational programs willbe as important as our outlays for construction, opera-tions, and scientific research. With our ALMA partners,we will engage a younger generation of scientists andengineers in bonds that leap national borders and inte-grate education with research.

We at NSF extend our best wishes for the speedy com-pletion of ALMA and for a lifetime of spectacularachievements.

Wayne Van CittersDirector, NSF Division of Astronomical Sciences

It is a great personal pleasure for me to be here withfriends from Chile, Europe, North America, and Japan atthis historic occasion. As I was thinking about thisceremony on the plane flight down to Chile, it remindedme of the first site visit I held on coming to NSF almost25 years ago. We were reviewing the fledgling millime-ter interferometer built by Caltech in the Owens Valleyof California. One of the major points of discussion atthe time was whether it was scientifically cost effectiveto expand the baseline (the distance between the twoantennas) from 50 meters to 100 meters. There was asubstantial body of thought that this would not beworthwhile, for after all, surely there would not be anysource that would be bright enough on such smallscales to be detected. Today we break ground for amillimeter interferometer that will have baselines meas-ured in thousands of meters.

Very soon the question turned to one of whether it wasworthwhile to use millimeter telescopes, and millimeterinterferometers in particular, to observe molecular gasin external galaxies. Surely there would not be anydetail visible at the necessary brightness. Today we

eagerly await ALMA’s ability to map molecular gas inthe first generation of galaxies; this gas alreadycontains elements heavier than hydrogen that wereforged in the first generations of stars to form, less thana billion years after the origin of time itself.

How far we have come in our understanding, ourambition, our sheer scientific audacity in less than oneprofessional lifetime.

The scientific promise of ALMA is compelling and itscontributions to our comprehension of the Universe andour place in it will be profound. As Rita noted in herremarks, the questions to which we seek answerstranscend national boundaries and cultural divides. Soin addition to breaking ground for a powerful scientificinstrument today, let us also pledge to respond to apowerful challenge put to the American AstronomicalSociety by Arthur Carty last year in Nashville. Let theALMA partnership use the universal appeal of astronomyto bind us together across oceans and between continents.

I believe that a world pursuing a global strategy todiscover how the beauty that surrounds us today cameto be, including we who are enjoying it, that worldmust ultimately put aside suspicion, hatred, racism andgreed. Let us dedicate ALMA as an instrument ofunderstanding, not only of scientific fact but also ofourselves. Through ALMA let us leave a legacy ofmutual respect, of free and open inquiry, and of love ofthe truth to our children - indeed to the children of theworld community.

K. Y. Lo Director, NRAO

Distinguished guests, ladies and gentlemen,

On behalf of the National Radio AstronomyObservatory, the North American (NA) Executive of theALMA Project, I welcome you to this ground breakingceremony. Today, we are celebrating the realization ofthe aspirations of many astronomers for more thantwenty years to build a powerful array that can let uspeer into the beginning of the Universe, galaxies, starsand planets, and perhaps even life. ALMA is truly oneof the cornerstones of major ground-based telescopes inthe many decades to come.


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In the US, the beginning of ALMA went back to 1982when the NSF Committee on the Future of Millimeter-wave Astronomy headed by Professor Alan Barrett ofMIT recommended the building of a national millimeter-wave array, called the MMA. Over the years, I rememberparticipating in many workshops on the development ofthe MMA.

As a member of the NRAO Visiting Committee, Ivisited the Plano de Chajnantor, Pampa la Bola andRio Frio in 1996. They were at that time potential sitesfor the MMA, the Large Millimeter and Sub-millimeterArray of Japan, and the Large Southern Array ofEurope. I remember distinctly thinking at that time: therational thing was for the three very similar projects tobecome one, but for practical and political reasons, itwould never happen. Here we are today, commemorat-ing basically the merging of the US and Europeanprojects, and we are fully expecting the final step ofmerging with the Japanese project in 2004. How wrongI was, but what a triumph for astronomy andinternational relations!

For making the North American participation in ALMApossible, I must thank the US National ScienceFoundation for supporting the ALMA and the CanadianNational Research Council for contributing to theproject. In addition, we are very honored to have boththe US Ambassador Brownfield and CanadianAmbassador Giroux joining us in this ceremony.

There are many people on the NA side to recognize forbringing ALMA into reality, but I would like to mentionthree names. The first is Bob Dickman at the NSF. Hehas been the champion of ALMA within NSF for manyyears and continues to play an important role by servingon the ALMA Board. Second is my predecessor,Paul Vanden Bout. Without his persistence for more than15 years to get the MMA, and later ALMA, funded, hisgenius of forming international alliances, and manyother efforts including the selection of Chajnantor as asite, we would not have ALMA today. Last but notleast, AUI President Riccardo Giaconni. As ESODirector General, he signed the key internationalagreement with Paul Vanden Bout that led eventually tothe Bilateral ALMA that we are celebrating today. Nowthat he has joined the NA side, he is making sure that

we do not deviate from getting ALMA built on timeand on budget.

As NRAO Director, I have the heavy responsibility toensure our Observatory will do its part to get this verycomplex telescope array built by 2012. Of course, muchof the work is borne by the NRAO ALMA Team. Thereare too many to name, but I would like to recognize afew key members who are here today: our ALMADivision Head, Darrel Emerson, Project ManagerMarc Rafal, Project Scientist Al Wootten, AUI VicePresident Pat Donahoe, Eduardo Hardy our representa-tive in Chile, and Simon Radford who has worked onpreparing the site here for almost ten years.

Finally, I would like to thank the Chilean government atall levels, our Chilean astronomy colleagues, and thecitizens of Region II, all of whom so graciously allowALMA to be built in their beautiful country.

I look forward next to the ALMA dedication ceremonyin 2012 and to making my first image with the array.

Thank you very much for joining us in this celebration.

Riccardo Giacconi AUI President

I have been asked to make a brief statement about thescientific significance of the event we celebrate heretoday. The exciting discoveries in astronomy and astro-physics of the last decade and the great technologicaladvances in astronomical instrumentation hold thepromise that in the beginning of this new millenniumwe will take a giant step forward in our understandingof the cosmos. In the last decade we have, for the firsttime, discovered the existence of numerous planetsaround stars other than the sun; we have peered at thevery edge of the visible universe only a few hundredthousand years after the big bang to study the seeds ofgalaxy formation; we have found evidence of a newform of energy that might be the largest constituent ofthe universe. We have found that galaxies and clustersof galaxies were formed much earlier than we hadthought and that most galaxies (including our own) har-bor massive black holes. The study of black holephysics and of the phenomena occurring in γ ray burstsources has made great advances and holds the promise


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to test theories of gravity, including general relativity,under strong field conditions. For the first time we havedetected neutrinos from a supernova explosion andextended astrophysical observations of specificphenomena to particle detection.

An ambitious plan of study has emerged for the nexttwenty or thirty years which combines the study of theextremely large with that of the extremely small. Tounderstand the Universe we need to further advance ourknowledge of the fundamental laws of physics and ofthe elementary constituents of matter. The Universeitself is becoming the laboratory where the very highenergies, high densities, and strong fields provide thetesting ground for these new laws. This plan anticipatesthe development of new and more powerfulobservational facilities in all the wavelengths of theelectromagnetic spectrum, as well as particle detectors,through international collaborations on a scale neverseen before. ALMA will be at the forefront of thesefacilities and hopefully will provide a model for suchcollaborative efforts. ALMA observations will serve toelucidate many of the most important questions inastrophysics today.

ALMA will permit us to study the distant Universe andobserve the first seeds of galaxy formation and thesubsequent galaxy evolution. It will have the requiredsensitivity, resolution, and bandwidth to observe thesmall scale anisotropies in the cosmic microwave back-ground imprinted by the initial fluctuations at Z ~ 100and the distortions due to the Sunyaev-Zeldovich effectin clusters of galaxies. Together with X-ray observationthis will permit direct measurement of the size andcurvature of the universe.

ALMA will have unsurpassed sensitivity and imagingcapabilities for molecular spectroscopic study of exter-nal galaxies and will be able to detect the first galaxiesformed through their dust emission at Z > 20. It will beable to study star formation cores in nearby galaxiesand assess the role of morphology and environment intheir dynamic and chemical evolution. The setting ofALMA in the southern hemisphere will permit detailedstudies of the large and small Magellanic clouds. Thestudy of organic molecules in interstellar space will

provide indispensable clues to the origin of life in theuniverse. ALMA will offer unique capabilities to study supermassive black holes in all galaxies including our own.With the same angular resolution of the Hubble SpaceTelescope, ALMA can resolve the disks fueling thecentral black holes in galaxies as far as Virgo and yieldgeometry, physical conditions and kinematics of thegas. Finally if used as the prime component in a worldwide millimeter wave VLBT network, ALMA wouldallow us to map the structure of active galactic nucleiwith a resolution of 10 micro arc seconds, the highestresolution achievable in astronomy. Thus ALMA willcontribute to the all wavelength attack on the funda-mental problems of the origin of the universe, ofdevelopment of structures and possibly of organic life.

I would like to conclude with a very brief personalremark. I consider myself extremely fortunate in havinglived in this epoch of advances in astronomy notequaled since the time of Copernicus, Galileo, Kepler,Tycho, and Newton. I was privileged in being associatewith some of the great enterprises in our field: the startof X-ray astronomy and the development of Chandra,the operation of the Hubble Space Telescope, the devel-opment of the Very Large Telescope on Paranal, andnow the start of the ALMA Project. In some of myrecent papers I found myself using data from Chandra,HST and VLT to clarify, after forty years of work, themystery of the X-ray background. Still some of theX-ray sources we observe in the deepest survey are sofaint that neither HST nor VLT can identify them, andthey may well be new types of celestial objects. I hopeALMA will be able to solve this new mystery in mylifetime. I would like to end by thanking our host,Chile, for joining us in this noble voyage of discoveryand making this enchanted land the home for some ofthe most important of these great enterprises.

Me gustaría concluir agradeciendo a nuestro anfitrión,Chile, el haberse unido a nosotros en este noble viaje dedescubrimiento, haciendo esta tierra encantada el hogarde algunas de las mas importantes de estas grandesaventuras. Muchas gracias!


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ALMA Science Meeting

University of Maryland Conference CenterMay 14-15, 2004

In October 1999, a meeting was held in Washington, D. C.to bring together scientists working on the developmentof what would become ALMA to review the scientificprogram planned for the array and how that programinteracted with the science goals of other astronomicalfacilities contemporaneous with it. The results of thatmeeting were published in Science with ALMA, ASPConference Series Volume 235. Much of the researchplanned for ALMA at that meeting has appeared in theALMA Design Reference Science Plan, a collection ofexperiments planned for ALMA recently presented bythe ALMA Project and available at www.alma.nrao.edu.

As a story elsewhere in this Newsletter relates, ALMAconstruction is now well under way. Planning for its

operation has also progressed, and a new buildingwhich will house the North American ALMA ResourceCenter is under construction in Charlottesville. EarlyScience is expected from a subset of ALMA telescopesby the end of 2007.

An ALMA Town Hall meeting will be held at the AASmeeting in Atlanta on January 8 at 1:00-2:00 p.m., inthe Regency VI room. The session will focus on ALMAscience and on the interaction between ALMA and theAmerican user through the ALMA Resource Center inCharlottesville.

In a meeting to be held at the University of MarylandConference Center May 14-15, 2004, astronomers areinvited to discuss the present state of plans for ALMA,ALMA's scientific goals and how best to enable them,and the face ALMA presents to its scientists users.Further details will be available soon.

The Green Bank Telescope

The autumn months have brought a number of enhance-ments to GBT operational capabilities and continuedprogress on development projects. In operational areas,the 18-26.5 GHz and 40-50 GHz receivers have nowbeen installed, the Spectrometer is performing robustly,observations are now easier to configure—with moreimprovements on the way—and there are now conven-ient methods to export data to a number of analysispackages. As a consequence of these enhancements,most classes of observing projects can now be scheduledroutinely. The azimuth track issues described in pastNRAO Newsletters have been relatively stable over thepast few months and progress continues toward a long-term resolution. The staff and university collaboratorsare making progress on a number of developmentprojects, including the Precision Telescope ControlSystem, the Penn Array Camera, the 26-40 GHz(Ka-band) receiver, and the Pulsar Spigot Mode of thespectrometer.

The 18-26.5 GHz (K-band) receiver was reinstalled inOctober and is in routine use for science projects.

January 2004 ALMA and Green Bank Issue 98

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H. A. Wootten

GREEN BANK

The Green Bank Telescope (GBT)

Spectral baseline quality and calibration accuracy aremuch improved from last spring, and nearly all of theobserving requests for this receiver can now be supported.Engineering modifications of the 40-50 GHz (Q-band)receiver were completed over the summer and early falland the receiver was installed in late November. Finalcommissioning of this receiver will be completed inDecember and January, and initial science projects areplanned for February. The 12-15 GHz (Ku-band)receiver has also been upgraded with new low noiseamplifiers from the Central Development Lab.

The GBT Spectrometer is now in routine use in nearlyall of its priority autocorrelation modes. Improvementsin hardware, firmware, and software have largely elimi-nated system crashes, and the device runs robustly forlong periods. Additional improvements including are-design of the Long Term Accumulator (LTA) card,which mostly affects maintainability, are underway.

A new tool for expediting observing configurations isunder development. A beta version of this tool wasreleased in November and has already been in use bystaff astronomers and several observers. Initial responseto the tool has been very positive. Further enhance-ments to the tool are underway and are planned forrelease in the first quarter of 2004.

A straightforward method to export GBT data to exter-nal data analysis packages is also under development.In November, the beta release of a Single Dish FITS(SDFITS) writer was released. Using as input the GBTdevice FITS files produced by each observation, theSDFITS application writes a consolidated FITS filesuitable for export to other packages. This format canalready be read by IDL and AIPS++. Extensions to thekeywords and additions to the information content ofthe SDFITS files are underway, with final versionrelease expected in early 2004.

Studies of the GBT azimuth track continue. The fieldtrial of the test modification of one splice jointperformed last June is proceeding. A detailed, quasi-dynamical finite element analysis of the existing trackand some modification alternatives is underway at thefirm of Simpson, Gumpertz, and Heger. Measurementsof track deflections and motions to be used to test thefinite element model were made in November. We

expect to assimilate the information necessary to makea decision about the best course of action for the trackby early 2004. The track itself has been relatively stableover the past few months. In October, a small crack inone wear plate that had been initially detected last win-ter propagated to the extent that replacement of theplate was warranted. We have several spare plates onhand, and the replacement was accomplished quickly.

Good progress continues on the major GBT develop-ment projects. The Precision Telescope Control Systemproject that will enable operation to 115 GHz has had anumber of successes this autumn. An in-progressreview of the project was held on 3-4 December. ThePTCS Project team has been using antenna structuraltemperature sensors to predict radial focus and bothazimuth and elevation pointing errors. A prototype ver-sion of this was demonstrated in November with greatsuccess, and development of the production equivalentshould quickly follow. At the same time, our ability todisentangle gravitational and thermal effects hasallowed us to significantly improve both the traditionalpointing and focus-tracking models. Latest results areposted on the PTCS web pages atwww.gb.nrao.edu/ptcs.

A critical design review of the Penn Array Receiver, a64-pixel bolometer camera for the 3 mm band was heldon 17-18 October. The panel members were Drs.William Duncan (chair), Dale Fixsen, and Chris Carilli.The panel was enthusiastic about the project and madea number of valuable comments and recommendationsthat should prove very helpful to the project. The cam-era is slated for delivery in 2005.

Work on the 26-40 GHz (Ka-band) receiver continues.First cool-down of the cryostat is expected by January,with completion of the receiver by the end of March.We expect to perform initial engineering tests in Spring2004, with first scientific use beginning in the fall.

The Pulsar Spigot Mode of the GBT Spectrometer hasseen first scientific use and is almost ready for use byknowledgeable experts. The Spigot Mode allows veryfast data dumps at wide bandwidths (up to 800 MHz).The project is a collaboration of David Kaplan(Caltech) and the NRAO staff.

January 2004 Green Bank Issue 98

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P. R. Jewell

GENERAL: Please use the most recent proposal cover-sheets, which can be retrieved at http://www.nrao.edu/administration/directors_office/tel-vla.shtml for theVLA and at http://www.nrao.edu/administration/directors_office/vlba-gvlbi.shtml for the VLBA.Proposals in Adobe Postscript format may be sent [email protected]. Please ensure that the Postscriptfiles request US standard letter paper. Proposals mayalso be sent by paper mail, as described at the webaddresses given above. FAX submissions will not beaccepted. Only black-and-white reproductions ofproposal figures will be forwarded to VLA/VLBAreferees. Finally, VLA/VLBA referee reports are nowdistributed to proposers by email only, so pleaseprovide current email addresses for all proposal authorsvia the most recent LaTeX proposal coversheets.

VLA: The maximum antenna separations for the fourVLA configurations are A-36 km, B-11 km, C-3 km,and D-1 km. The BnA, CnB, and DnC configurationsare the hybrid configurations with the long north arm,which produce a circular beam for sources south ofabout -15 degree declination and for sources north ofabout 80 degree declination. Some types of VLA obser-vations are significantly more difficult in daytime thanat night. These include observations at 90 cm (solar andother interference; disturbed ionosphere, especially atdawn), deep 20 cm observations (solar interference),line observations at 18 and 21 cm (solar interference),polarization measurements at L band (uncertainty inionospheric rotation measure), and observations at 2 cm

and shorter wavelengths in B and A configurations(tropospheric phase variations, especially in summer).Proposers should defer such observations for a configu-ration cycle to avoid such problems. In 2004, theD configuration daytime will involve RAs between05h and 11h. Current and past VLA schedules may befound at http://www.vla.nrao.edu/astro/prop/schedules/old/.EVLA construction will continue to impactVLA observers; please see the web page athttp://www.aoc.nrao.edu/evla/archive/transittion/im.

VLBA: Time will be allocated for the VLBA onintervals approximately corresponding to the VLAconfigurations, from those proposals in hand at thecorresponding VLA proposal deadline. VLBA proposalsrequesting antennas beyond the 10-element VLBA mustjustify, quantitatively, the benefits of the additionalantennas. Any proposal requesting a non-VLBAantenna is ineligible for dynamic scheduling, and fixeddate scheduling of the VLBA currently amounts to onlyabout one quarter of observing time. Adverse weatherincreases the scheduling prospects for dynamicsrequesting frequencies below about 10 GHz. When the

January 2004 Socorro Issue 98

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SOCORRO

Configuration Starting Date Ending Date Proposal Deadline

B 1 7 Oct 2003 19 Jan 2004 2 Jun 2003CnB 30 Jan 2004 16 Feb 2004 1 Oct 2003C 20 Feb 2004 17 May 2004 1 Oct 2003DnC 28 May 2004 14 Jun 2004 2 Feb 2004D 18 Jun 2004 13 Sep 2004 2 Feb 2004A(+PT) 01 Oct 2004 10 Jan 2005 1 Jun 2004BnA 21 Jan 2005 07 Feb 2005 1 Oct 2004B 11 Feb 2005 09 May2005 1 Oct 2004CnB 20 May 2005 06 Jun 2005 1 Feb 2005C 10 Jun 2005 05 Sep 2005 1 Feb 2005

VLA Configuration Schedule; VLA / VLBA Proposals

Approximate VLA Configuration ScheduleQ1 Q2 Q3 Q4

2003 D D,A A,B B2004 C D D,A A2005 B B,C C D2006 D,A A B C

VLA-Pie Town link is in use during the VLA’s A con-figuration, we will try to substitute a single VLAantenna for Pie Town in a concurrent VLBA dynamicprogram. Therefore, scheduling prospects will beenhanced for VLBA dynamic programs that can accom-modate such a swap. See http://www.aoc.nrao.edu/vlba/schedules/this_dir.html for a list of dynamic programswhich are currently in the queue or were recentlyobserved. VLBA proposals requesting the GBT, theVLA, and/or Arecibo need to be sent only to theNRAO. Any proposal requesting NRAO antennas andantennas from two or more institutions affiliated withthe European VLBI Network (EVN) is a Global pro-posal, and must reach BOTH the EVN scheduler andthe NRAO on or before the proposal deadline. VLBAproposals requesting only one EVN antenna, orrequesting unaffiliated antennas, are handled on abilateral basis; the proposal should be sent both to theNRAO and to the operating institution of the otherantenna requested. Coordination of observations withnon-NRAO antennas, other than members of the EVNand the DSN, is the responsibility of the proposer.

B.G. Clark, J. M. [email protected]

VLBI Global Network Call for Proposals

Proposals for VLBI Global Network observing are han-dled by the NRAO. There are three Global Networksessions per year, with up to three weeks allowed persession. The Global Network sessions currently plannedare:

Any proposal requesting NRAO antennas and antennasfrom two or more institutions affiliated with theEuropean VLBI Network (EVN) is a Global proposal,and must reach BOTH the EVN scheduler and theNRAO on or before the proposal deadline. FAX sub-missions of Global proposals will not be accepted. Afew EVN-only observations may be processed by the

Socorro correlator if they require features of the EVNcorrelator at JIVE which are not yet implemented.Other proposals (not in EVN sessions) that request theuse of the Socorro correlator must be sent to NRAO,even if they do not request the use of NRAO antennas.Similarly, proposals that request the use of the EVNcorrelator at JIVE must be sent to the EVN, even ifthey do not request the use of any EVN antennas. Allrequests for use of the Bonn correlator must be sent tothe MPIfR.

Please use the most recent proposal coversheet, whichcan be retrieved at http://www.nrao.edu/administration/directors_office/vlba-gvlbi.shtml. Proposals may besubmitted electronically in Adobe Postscript format.For Global proposals, those to the EVN alone, or thoserequiring the Bonn correlator, send proposals [email protected]. For Global proposalsthat include requests for NRAO resources, send propos-als to [email protected]. Please ensure that thePostscript files sent to the latter address request U. S.standard letter paper. Proposals may also be sent bypaper mail, as described at the web address given. Onlyblack-and-white reproductions of proposal figures willbe forwarded to VLA/VLBA referees. Finally,VLA/VLBA referee reports are now distributed toproposers by email only, so please provide currentemail addresses for all proposal authors via the mostrecent LaTeX proposal coversheet.

B.G. Clark, J. M. [email protected]

VLBA Spacecraft Navigation Pilot Project

A VLBA Spacecraft Navigation Pilot Project has beeninitiated. The project, funded by NASA, will study sev-eral aspects of VLBA phase-referencing measurementsas a vital adjunct to conventional spacecraft navigation.

The central task will be carried out in collaborationwith several groups at the Jet Propulsion Laboratory toassess the feasibility of this approach. This study willinclude an evaluation of the precision achievable viaphase-referenced VLBA observations of spacecraftdownlink transmitters and the enhancement of naviga-tion results produced by the inclusion of suchmeasurements in the overall solution.


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05 Feb to 26 Feb 2004 01 Oct 200320 May to10 Jun 2004 01 Feb 200421 Oct to 11 Nov 2004 01 Jun 2004

Date ProposalsDue

In addition, NRAO will develop designs and cost esti-mates for upgrading VLBA hardware, software, andoperational procedures in several areas. These would allbe required to support routine spacecraft navigationobservations, with adequate sensitivity, at NASA’s newspace communication frequency band:

We anticipate that the project will show a mutually bene-ficial arrangement to be possible, with NRAO providinga significant quantity of spacecraft navigation results toNASA, while NASA provides the substantial upgrades,outlined above, to the VLBA’s observational capabilities.With these upgrades, we expect that the number of hoursavailable for astronomical observing will be at least ashigh as the average over the last few years.

NASA’s support for the Pilot Project has made possiblethe participation, at fractional work-year levels, ofNRAO personnel from almost all divisions at the AOC,and from the Central Development Laboratory inCharlottesville.

J. D. Romney

VLBI Using Arecibo

Potential proposers of VLBI observations requiringhigh sensitivity are reminded that they may propose touse the 305-m Arecibo telescope along with the VLBAfor sources in the declination range visible by Arecibo,between -1 degrees and +38 degrees declination, and instandard VLBA frequency bands below 10 GHz. Theseproposals should be submitted as usual to NRAO,

where they will be refereed by the normal process; theyneed not be submitted to Arecibo. Proposals shouldinclude a specific justification of why the addition of theArecibo telescope is important for the proposed science.

The Arecibo slew rates of 24 deg/min in azimuth and2.4 deg/min in zenith angle will often permit usefulphase referencing with both the VLBA and Arecibo.Proposers should remember that Arecibo always operateswithin 19.7 deg of the zenith, and that azimuth drivesare multiplied over real angle by cosec(zenith angle).The typical improvements in fringe-detection andimage sensitivity by including Arecibo with the VLBAare a factor of 5 or better, depending on the frequencyand zenith angle. Recent VLBI programs that have beencarried out using Arecibo include imaging of luminousinfrared galaxies (e.g., Momjian et al. 2003, ApJ, 597,809), supernova detection in Arp 220, imaging of thegamma-ray burst GRB 030329, and various VLBIobservations of pulsars and OH megamasers.

Please see http://www.naic.edu/aomenu.htm for moreinformation about the observing properties of theArecibo telescope. By following the appropriate links,one can find details about the sensitivity at variousbands, complete lists of VLBI observations carried outat Arecibo, and other useful information. Over the nextfew months, we will be working on achieving smootherVLBI operations with Arecibo, including the routineprovision of calibration data for the VLBI observers.

J. S. Ulvestad, C. Salter (NAIC)

VLA Calibration Transfer inVLBI Experiments

The VLA can now be treated much more like a VLBAantenna for purposes of calibrating VLBI experimentsthat include either the phased VLA or a single VLAantenna. This is possible since we recently started todistribute the VLA gain curve, VLA system temperature,and VLA weather information harvested during VLBIexperiments in the form of tables attached to the corre-lated data. The AIPS calibration of the VLA single dishantenna in a VLBI experiment can be processed alongwith the VLBA antennas using the VLBAUTIL


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Upgrades to the VLBA correlator to incorporatethe spacecraft ephemeris into the wavefront delaymodel, and to add new tables to the output files tomaintain complete model accountability.

Upgrades to the VLBA correlator's playbackinterface, and to the station and correlator controlsoftware, to exploit the full 1-Gbps bandwidth ofthe disk-based Mark 5B recording system.

New Ka-band (33 GHz) receiver systems.

Upgrades to VLBA operational procedures tooptimize our ability to perform spacecraft naviga-tion observations with minimal impact on theVLBA's ongoing astronomy progra

procedures described in Appendix C of the AIPS cook-book. Using the VLA phased array in the observationstill requires the user to insert the source flux density inthe “SU-table” before calibration. In rare cases in whichmultiple setups in the same frequency band are used,the new, default calibration procedure may not fullywork and observers are required to use the previous“ANTAB” method to obtain proper calibration. Formost users there will be no extra calibration burdenwhen using the VLA in a VLBA observations.Currently we are looking into similar improvements tostreamline the calibration for VLBI experiments corre-lated in Socorro that involve the GBT and Arecibo.

L. O. Sjouwerman

Large VLA Proposals

We remind potential proposers that the February 2, 2004proposal deadline is a deadline for VLA large proposalsfor the next VLA configuration cycle. This deadlinewill be for observations during the time period beginningwith the A configuration during the last trimester of2004, and extending through the D configuration at theend of 2005. For more details, see NRAO NewsletterNo. 97 or http://www.vla.nrao.edu/astro/prop/largeprop/.

J. S. Ulvestad

Interferometry Computing

We have reorganized a number of areas of interferome-try computing in order to focus more clearly on theoperating and planned interferometers in NRAO. Thisreorganization is aimed at creating a tighter linkbetween the ALMA and EVLA project requirements,and those who are responsible for delivering softwareproducts to meet those requirements.

During the summer, we formed a matrix-managedInterferometry Software Division, which is co-managedby Brian Glendenning (representing ALMA) and JimUlvestad (representing EVLA, VLA, and VLBA). ThisDivision includes Integrated Product Teams responsiblefor post-processing software, data pipelines, dataarchives, and proposal handling. To ensure coordinationwithin the NRAO of the long-term developments that

are necessary for all NRAO’s telescopes, Doug Todyhas been appointed chief architect for theInterferometry Software Division. Doug’s duties willinclude guiding the efforts of Integrated Product Teamsin data flow and data management areas as part of hiscontinuing efforts in the development of the VirtualObservatory.

Within VLA/VLBA Operations, the previousComputing Division has been split into two newdivisions. One division is the Computing InfrastructureDivision, responsible for all local computing infrastruc-ture, including systems administration, software/hardwareupgrades and maintenance, and communications. JamesRobnett, who formerly led the systems administrationeffort in the previous Computing Division, has beenappointed Head of the Computing InfrastructureDivision. The other new division is the EVLAComputing Division, responsible for all aspects ofEVLA software development, including those EVLA-specific activities formerly housed in the end-to-endproject within Data Management. Gustaaf van Moorsel,who headed the previous Computer Division, has beenappointed head of the EVLA Computing Division.

Of course, we will continue our important efforts tomaintain and upgrade the current operational telescopes,the VLA and VLBA. Support activities from personnelin the Computing Infrastructure Division continue to besupervised within that Division. In addition, severalmembers of the new EVLA Computing Division haveresponsibilities for the operating telescopes. Theseresponsibilities will be coordinated by Peggy Perley, theHead of the Array Operations Division.

J. S. Ulvestad, B. E. Glendenning

Antenna Bearing Replacements

An elevation bearing on the VLBA antenna in St. Croixwas replaced in July 2003, and the azimuth bearing onVLA antenna 15 was replaced in August 2003. Thebearings were replaced because metal flakes werefound in grease samples collected from them. A highmetal content in the grease indicates a failed bearing orexcessive bearing wear.


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The elevation bearing on the VLBA antenna in St.Croix failed because of an excessive axial load on thebearing, which is designed to support radial loads only.The axial load arises from a subtlety in the design ofthe bearing support structure and was most likelyinduced when the bearing was first installed. An eleva-tion bearing at the VLBA antenna in Los Alamos failedin a similar manner in 2001. Since all VLBA antennasare essentially identical, we can expect similar bearingfailures at other VLBA antennas in the future.

Our strategy for replacing VLBA elevation bearings isto continue monitoring bearing grease samples and toreplace those bearings that show excessive metalcontent in the samples. Replacements for the bearingswill be of a new design that can support both axial andradial loads. This strategy extracts maximum use of theexisting bearings and minimizes bearing replacementcosts.

A very aggressive program to replace all VLBAelevation bearings is not warranted at this time becausebearing wear can be detected prior to a severe failure.For example, the grease samples taken at St. Croixsuggested that the bearing was damaged, but theantenna showed no degradation in its pointingperformance.

The replacement of the 10-foot diameterazimuth bearing on antenna 15 is theseventh azimuth bearing replacementundertaken by the Engineering ServicesDivision. As with the other azimuthbearings that have been replaced, aninspection of the replaced bearing onantenna 15 showed that the metal flakesin the grease were caused by excessivebearing wear. The wear is attributed tonormal operations over the 20-plus yearservice life of the bearings and, possibly,inadequate lubrication of the bearingswhen they were originally installed. Morebearing replacements will be required tomaintain antenna infrastructure over thelifetime of the EVLA.

If azimuth bearing wear can be detectedsoon enough, the used bearing can be

reconditioned by a bearing manufacturer and reinstalledon another antenna at a cost that is $20K less than thecost of a new bearing. Of course, a small number ofnew bearings must be purchased to return antennas tooperation while the used bearings are reconditioned. Werecently arranged for the purchase of four new azimuthbearings and the reconditioning of a used bearing.These bearings will be used to replace two azimuthbearings in each calendar year of 2004 and 2005.

M. M. McKinnon

X-Ray and Radio Connections

“Almost by definition, high energy sources are non-thermal and emit throughout the electromagnetic andother spectra and spectrally chauvinist interpretations oftheir behavior are incomplete” (Blandford 2003).

NRAO and AUI are sponsoring the meeting “X-Rayand Radio Connections” with the Chandra X-RayCenter and Los Alamos National Laboratories to takeplace in Santa Fe Tuesday, February 3, through Friday,February 6, 2004. The purpose of the meeting is toencourage increased scientific return from multi-wavelength astronomy involving X-ray and radioinstrumentation. Currently, observations of high-energy


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The installation of the new elevation bearing and its pillow black mount at the VLBAantenna in St. Croix. Photograph by Pete Allen.

phenomena sometimes are split among several commu-nities that independently investigate objects in theirown waveband. This can lead to reduced scientificresults compared to those possible from multiwave-length programs.

This meeting will provide an opportunity forresearchers to review underlying physical models,compare x-ray and radio observations, start newcollaborations and develop a list of areas where newobservations and theoretical development could signifi-cantly advance our understanding in the next few years.

The topics of the meeting were chosen to focus onscientific areas where cross fertilization between theoryand observations in both x-ray and radio wavebandsprovides a key to the underlying physical processes. Weknew from the outset that there were numerous fieldsthat would benefit from an “x-ray and radio connec-tions” session. However, it was also clear that a smallmeeting would best facilitate discussion and thatfocusing on a few topics would be better than a shotgunapproach. The chosen topics include: massive starcluster outflows, colliding stellar winds, supernovaremnants, pulsar wind nebulae, dissipation of jets andlobes, and cluster mergers. If this meeting is a successwe would consider planning “X-ray and RadioConnections II” (no sooner than January 2006) whichwould cover topics that we were unable to cover in thismeeting. The website is http://www/aoc/nrao.edu/events/xraydio/.

Confirmed speakers include:Robert Berrington (NRL) Henrik Beuther (Harvard-Smithsonian CfA) Michael Corcoran (USRA & NASA-GSFC) Anne Decourchelle (Saclay) Tracey DeLaney (U Minnesota) Dave DeYoung (NOAO Tucson) Jean Eilek (New Mexico Tech) Luigina Feretti (CNR Bologna) Martin Hardcastle (U Bristol) John Kirk (MPI-K Heidelberg) Robert Laing (U Oxford) Andrew Melatos (U Melbourne) Julian Pittard (U Leeds) Steve Reynolds (NC State) Craig Sarazin (U Virginia)

Meeting Chairs:Kristy Dyer (NSF Astronomy & Astrophysics

Postdoctoral Fellow, NRAO-Socorro)Lorant Sjouwerman (Scientific Services,

NRAO-Socorro)K. K. Dyer, L. O. Sjouwerman

Education and Public Outreach atNRAO-Socorro

NRAO Socorro’s Education and Public Outreach effortsreached a milestone this summer with the opening ofthe gift shop at the Very Large Array Visitor Center.Ground was broken in early March, and the shopopened its doors for business on June 18. The purposeof opening a gift shop was to provide our tourists afriendly face to greet them and to answer their ques-tions. In the past, our visitor center was not staffed andtourists were left to figure out their own answers aboutradio astronomy, the VLA, or the nearest gas station.Our clerks enhance the visitors’ experiences withanswers and information resources. The revenue raisedin gift shop proceeds will pay the clerks’ salaries.

From a commercial standpoint, the gift shop providesour guests, many of whom have “wanted to come to theVLA for a long time,” with souvenirs of their visit. Wesell primarily NRAO logo merchandise, books,“Contact” DVDs, and jewelry produced by artisans


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VLA Visitor Center Gift Shop

from the local Alamo Navajo Reservation. For guestswho visit the VLA outside normal gift shop hours, wedo sell some of our merchandise mail-order over theweb at www.vla.nrao.edu/genpub/shop/.

A second milestone was reached with the completion ofthe first two elements of the N2I2 (NRAO/New MexicoTech Instructional Interferometer). Work on the instru-ment began in 2000 with a planning meeting between

Robyn Harrison and Dave Westpfahl, culminating thisspring in “first light” from two 10-foot dishes located atEtscorn Observatory on the New Mexico Tech campus.The cooperative effort between NRAO and NewMexico Tech (NMT) involved funding and volunteerlabor from both entities.

NMT grad student Danielle Lucero, with after-hoursand weekend volunteer assistance from NRAO employ-ees Jim Muehlberg and Mike Revnell, built the addinginterferometer with a 24-meter east/west baseline. Asimple combiner sends a single signal to the 21cmreceiver, donated by Gareth Harris. The Sun,Cassiopeia A, Cygnus A, Taurus A, Virgo A, andSagittarius A have been successfully detected thus far.The setup can be used for single dish drift scans, inter-ferometer drift scans at meridian, and fringe detection.

The purpose of the N2I2 is to provide a “hands-on”instrument for teachers and students. It will be used as atool for learning about radio astronomy and interferometry,and to afford opportunities for research experiences. Atwo-week class for teachers is planned through NMT’sMaster of Science Teaching program, as well as shorterweekend workshops sponsored by NRAO. More infor-mation on the construction and testing of N2I2 can befound at www.nrao.edu/epo/amateur.

R. J. Harrison

NRAO Archives

The NRAO Archives is pleased to announce the avail-ability of a Web resource describing NannielouHepburn Dieter Conklin's career as the first US womanworking in radio astronomy: http://www.nrao.edu/archives/Conklin/conklin.shtml. "Nan Dieter Conklin:A Life in Science" was written by Dr. Conklin in 2001,and covers her work from 1946 -1977, beginning at theMaria Mitchell Observatory and ending at University ofCalifornia Berkeley.The NRAO Archives has been established to seek out,collect, organize, and preserve institutional records and

personal papers of enduring value which documentNRAO's historical development, institutional history,instrument construction, and ongoing activities. As thenational facility for radio astronomy, the NRAOarchives will also include materials on the history anddevelopment of radio astronomy in the U.S., particularlyif such materials are in danger of being lost or discardedby other institutions or individuals.

For further information, please contact NRAO ArchivistEllen Bouton, [email protected].

E. N. Bouton

January 2004 Socorro and In General Issue 98

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Danielle Lucero (NMT grad student) and Jim Muehlberg (NRAO)working on the NRAO/New Mexico Tech Instructional Interferometer.

IN GENERAL

Although it is the seventh brightest source in the 3Ccatalog, images of Hydra A (3C218) at low radio fre-quencies with good angular resolution have never beenavailable. Hydra A is a well known, powerful FR I radiogalaxy located in the core of a poor galaxy cluster atz = 0.0542. Observations of this source at frequenciesabove 5 GHz reveal bright inner jets which trace an “S”shape (Taylor et al. 1990) and combined cover roughly1.5' in a north-south direction.

A new analysis of VLA observations at 330 and 74MHz shows that the well-known bright inner jets ofHydra A are longer than previously seen, and extend forroughly 2' on both sides of the source. They then benddramatically and end in diffuse lobes. The entiresource covers nearly 8', or roughly 375 h-1

71 kpc (Lane etal. 2004). The synchrotron spectrum of Hydra A has arelatively flat slope in the radio core, which steepens in

the jets and lobes. It is not yet known what fraction ofFRI galaxies have similar diffuse extended structuresvisible at low frequencies, but they have been seen in afew other sources such as M87 in the core of the Virgocluster (Owen, Eilek, & Kassim 2000).

Recent X-ray observations of the thermal gas in thissystem show that Hydra A is surrounded by dense, coolgas which extends well beyond the bright radio jets(Nulsen et al. 2002) and is roughly aligned with the lowfrequency outer emission. This may be entrained clustercore gas which has been dragged out by buoyantly ris-ing outer lobes. Through a comparison of the new radiodata with recent X-ray observations, we will be able toinvestigate what dominates the energy budget in thecenter of this system.

Tracy Clarke (Univ. of Virginia),Wendy Lane (Naval Research Laboratory)

January 2004 New Results Issue 98

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The Many Faces of Hydra A: Low Frequency Observations Reveal the Big Picture

VLA images of Hydra A; 3C218. (left) 74 MHz, A-configuration image with ~25" resolution. (middle) 330 MHz, combined A-, B-, and C- con-figuration image, displayed at ~15" resolution. (right) The spectral index map of Hydra A between 330 MHz and 74 MHz is shown in color,with overlaid contours from the 330 MHz image at (1, 4, 16, 64, 512) × 54 mJy/beam (the 5σ noise level). The two frequencies were mappedwith a matching resolution of ~25" before being combined in this image.

74 MHz 330 MHz

NEW RESULTS

References:Lane, W. M., Clarke, T. E., Taylor, G. B., Perley, R. A.,

& Kassim, N. E. 2004, AJ (in press)Nulsen, P. E. J., David, L .P., McNamara, B. R., Jones, C.,

Forman, W. R., & Wise, M. 2002, ApJ, 568, 163

Owen, F. N., Eilek, J. A., & Kassim, N. E. 2000, ApJ, 543, 611

Taylor, G. B., Perley, R. A., Inoue, M., Kato, T., Tabara, H., & Aizu, K. 1990, ApJ, 360, 41

The detection of carbon monoxide (CO) emission from24 high redshift (z > 1) galaxies suggests that theirobserved high infrared luminosities (LIR > 1011 Lu)result from high rates of star formation. Alternatively,as a substantial fraction (possibly all) of these galaxiesharbor active galactic nuclei (AGN), the infrared lumi-nosities could also have an AGN origin. The detectionof CO emission is sufficient to establish the presence ofa reservoir of molecular gas required for star formation,

but not to establish that this gas ispresent in densities sufficient for starformation to occur.

Detection of emission from moleculeswith larger electric dipole momentsthan CO can provide a reliablesignature of star formation. Carbonmonosulfide (CS) and hydrogencyanide (HCN) are examples, eachrequiring gas densities of ~105 cm-3

for excitation of its energy levels,compared with ~300 cm-3 for CO. CSand HCN emission have been identi-fied with the high density gas in thecores of molecular clouds that areforming high-mass stars in the Galaxy.Previous detections of HCN emissionin ultra- luminous infrared galaxiesencouraged us to search for HCNemission in the Cloverleaf, a galaxy atz=2.5579 known to have large IRluminosity, that had been detected inseveral CO transitions.

The Cloverleaf is imaged by a gravita-tional lens into four componentsseparated by ~ 1". A lens model based

on radiation from the molecular gas makes it possibleto infer intrinsic source properties.

The VLA was used in D-configuration at the red-shiftedfrequency of 24.9149 GHz to image the Cloverleaffrom data obtained in 12 hours of integration (Figure 1).

The HCN(J=1-0) line was detected at the 6σ level witha peak flux density of 0.24 mJy and profile/width simi-


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Hydrogen Cyanide Emission from a Distant (z=2.6) Quasar — the Essential Signatureof a Starburst

Figure 1. The Cloverleaf in HCN(J=1-0) emission (green) at a resolution of 4". Thecontours are “square-root of 2” in units of 0.015 Jy km s -1, which is 1.7 times the rmsnoise, superimposed on an optical image made from HST archival data. A continuum hasbeen subtracted.

lar to that of CO(7-6). The HCN line luminosi-ty is comparable to that seen in ultra-luminousIR galaxies. Comparison with Arp 220 leads to astar formation rate in the Cloverleaf of103 Mu yr -1, 300 times that of the Milky Way.The Cloverleaf’s reservoir of 1010 Mu of dense,molecular gas will be depleted in a starburstlifetime of only 107 years, assuming 100 percentefficiency. The starburst accounts for about20 percent of the infrared emission, the balanceis presumably due to the AGN.

P. A. Vanden Bout, C. L. Carilli (NRAO)P. M. Solomon (SUNY-Stony Brook)

M. Guelin (IRAM)

References:

Kneib, J.-P., Alloin, D., Mellier, Y., Guilloteau, S.,Barvainis, R., & Antonucci, R. 1998, A&A, 329, 827

Solomon, P. M., Vanden Bout, P. A., Carilli, C. L.,& Guelin, M. 2003, Nature (December 11).

Globular clusters produce millisecond pulsars (MSPs) ata rate per unit mass that is up to an order-of-magnitudegreater than the Galaxy itself. Stellar interactions in thehigh-density cores of clusters can result in compactbinary systems where old neutron stars are “recycled”and spun-up to millisecond spin periods via accretion.The rotational stability of MSPs can be used to testgravitational theories in compact binaries; plasmaphysics can be constrained with measurements ofeclipsing binary MSPs; stellar evolutionary models aretested by multi-wavelength observations of binarypulsar companion stars; and properties of the clustersthemselves, such as the mass-to-light ratio and thedynamics of the cluster core, can be determinedthrough timing observations of several pulsars ineach cluster.

Using 7.8 hours of “First Science” data with the GBTtaken at 1370 MHz with the Berkeley-Caltech Pulsar

Machine (BCPM) on September 9, 2001 as part of amajor search for pulsars in globular clusters, we foundtwo binary MSPs after performing extensive computeranalysis in order to remove interference, correct for thedispersive effects of the interstellar medium, andaccount for the binary motion of the pulsars (Ransomet al. 2003).

Pulsar J2140-2310A (M30A) is an eclipsing 11- mspulsar in a 4-hr circular orbit around a low-mass(~ 0.1-0.2Mu) companion star. Timing observationsover the past two years have shown that the pulsar islocated only 4" from the core of the cluster and appearsto be spinning faster over time — an effect caused bythe pulsar’s motion in the gravitational potential of thecluster itself. Using this information, we show that thecluster core has a mass-to-light ratio > 0.5 (which isconsistent with cluster dynamical and evolutionarytheory) and that the pulsar itself has a low magnetic


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GBT Discovery of Two Binary Millisecond Pulsars in the Globular Cluster M30

Figure 2. Spectrum of HCN(J=1-0) emission observed in the Cloverleaftogether with the spectrum of CO(J=7-6) from Kneib et al. (1998), scaleddown by a factor of 200.

field strength (< 4.2×108 G) and high age(>108 yrs), which are typical values forMSPs. Using the precise timing position, wehave also identified plausible counterparts tothe system in both Chandra X-ray data (mostlikely from thermal emission from the neutronstar surface) and HST optical data (presum-ably from the companion star).

M30A also exhibits regular eclipses of itspulsed emission by the ionized wind from thecompanion star. Measurements of the pulsearrival times during eclipse ingress andegress show delays of up to 2-3 ms due to theplasma in the eclipse region. In addition, theduration of the radio eclipses seems to bedependent on the observing frequency.Additional measurements should allow theteam to constrain the likely eclipse mecha-nisms for this interesting system.

Pulsar J2140-23B (M30B) is a 13-ms pulsarin an as yet undetermined, yet clearly veryinteresting, orbit. The pulsar was detectedfor ~ 7 hours in the original discovery obser-vation but has not been seen since, duepresumably to the same intensive diffractivescintillation that plagues the observations ofM30A. However, the discovery data showedvery significant accelerations of the pulsar which con-strain the orbit to be highly eccentric (e > 0.5), of 1-10days in duration, and around a companion of 0.2-1.0solar masses. Future detections of this system, which isalmost certainly highly-relativistic, may allow theaccurate measurement of the masses of both the pulsarand the companion-numbers which are important forpulsar “recycling” theory and the determination of neu-tron star equations of state.

Timing observations of M30 with the GBT are continu-ing and the potential for both new science and additionalpulsars is strong.

References:Ransom, S. M., Stairs, I. H., Backer, D. C.,

Greenhill, L. J., Bassa, C. G., Hessels, J. W. T., & Kaspi, V. M. 2003, ApJ (in press, astro-ph/0310347).


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Pulse profiles from the 7.8-hr discovery observation of the 11-msbinary pulsar M30A (left) and the 13-ms eccentric binary pulsarM30B (right). The Doppler effects of each orbit have been removed,and two complete profiles are plotted for clarity. The underlying datashow the consistency of the pulsed emission as well as some effectsdue to interference as a function of time. Strong scintillation andportions of at least two eclipses of M30A are evident, including dis-persive delays to the pulse arrival times at eclipse ingress and egress.

Scott Ransom (Mc Gill University/MIT)

The astronomical SiO masers located in the extendedatmospheres of asymptotic giant branch (AGB) starsact as unique tracers of the physical processes at workin the near-circumstellar environments of cool, evolvedstars. The extended atmosphere is defined as the regionbetween the photosphere and the inner dust formationradius, usually lying at a distance of a few stellar radii.In AGB stars this is a complex region, dominated bythe mass-loss process and permeated by shocks, mag-netic fields and local temperature and densitygradients. The study of these regions is not easysince dust often prohibits optical observationsand the necessary spatial resolution is not yetavailable in other wavebands. However, theindividual SiO maser components havesufficiently high brightness temperatures toallow VLBI imaging of this region at sub-milliarcsecond (mas) resolution.

We have used the unique high-frequencycapabilities of the VLBA to monitor the43 GHz, v=1, J=1-0 SiO masers in theatmosphere of TX Cam. TX Cam is a ratherordinary, if somewhat evolved, Mira star witha spectral classification that varies between M8and M10 over a pulsation period of 557.4 days.It lies at a distance of 390 pc. Although thereare numerous lines from C- and S-rich

molecular species, no OH or H2Omasers have been detected.We originally selected TX Cam forthe monitoring program from asample of 25 other stars. It had aclearly circular structure in SiO,which looked relatively simple; itsflux density was usually high and itlay at a declination of 56°. Over aperiod of 3 years, from 1997—2000,we obtained 76 epochs of data fromthe VLBA. In the first half of thisperiod the epochs were separatedby two weeks, later this intervalbecame a month. The data analysisfollowed a pipeline procedure andthe resultant integrated velocitymaps of each epoch were combined

to form a movie (http://www.jb.man.ac.uk/~pdiamond/txcam_movie.mpg) with the first 44 epochs (Figure 1,Diamond & Kemball 2003).

The paper discusses the global proper motion of theSiO maser emission as a function of pulsation phase.We measure a dominant expansion mode betweenoptical phases ~0.7-1.5, confirming ballistic deceleration,


TXCam: The Movie (Part I)

Figure 1. Two frames from the TX Cam movie.

Figure 2. Inner radius plotted as a function of time showing how the SiObreathes with the stellar pulsation period.

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High-mass stars are important actors in the ecology ofthe interstellar medium (ISM) and the evolution ofgalaxies, yet there is no general theory of their forma-tion. Small sample size, large distances, clustering andcrowding, and high extinction conspire to make theprocess of high-mass star formation very difficult tostudy. Relatively few massive accreting young stellarobjects (YSOs) are known.

The Orion KL region is the archetypal and closestregion forming high-mass stars (~ 450 pc). It contains acompact centimeter and millimeter-wave continuumsource, designated “I” in the discovery survey, thatmarks the location of a deeply embedded YSO. Massflows at distances between 20 and 70 AU from source“I” are peppered with regions of SiO maser emission,which signifies temperatures of 1000-2000 K and H2densities of ~1010 cm-3. Because this is very highintensity emission, the VLBA can be used to map itwith resolutions of <1 AU and <1 km s-1 (both Doppervelocity and proper motion).

A three-year time series of monthly VLBA observationsis now being reduced. In the end, 2.5 TByte of images(64 GByte per epoch) will be compiled and proper

motions estimated. A combination of proper motion andDoppler velocity information will yield maps of 3Dvelocity and acceleration vectors.

Source “I” is important to study because it is possiblythe only YSO for which gas structure and 3D dynamicscan be fully resolved at radii < 102 AU, where outflowsare launched and collimated. Analysis of just a fewepochs suggests that the YSO, with a dynamical massof ~ 9 Mu , drives a rotating, bipolar, funnel-like windfrom the surface of an accretion disk that is seen nearlyedge-on. The limbs and bases of the funnels are tracedby SiO maser emission. By the end of the study, it willbe possible to determine whether the outflow motionsare ballistic or helical, thus answering the long-standingquestions: where are outflows collimated and aremagnetic fields important in the formation of massivestars?

Lincoln Greenhill (SAO) & Claire Chandler (NRAO)

Reference:

Greenhill, L. J., Chandler, C. J., Reid, M. J., Diamond, P. J., & Moran, J. M. 2004, Proc. IAU Symp. 221, ASP Conf. Series (in press).

and compare this to predictions from existing pulsationmodels for late-type, evolved stars. A challenge wasfiguring out how to measure the average radius of theemission, when clearly the ring of masers is nevercircular and is often asymmetric. We developed atechnique that estimated the inner radius at regularpoints around the ring and thus determined the averagesize for each epoch. Plotting the inner radius as a func-tion of time shows, in a dramatic fashion, how the SiObreathes with the stellar pulsation period (Figure 2).

In the movie, local infall and outflow motions areclearly superimposed on the dominant expansion mode,and non-radial local gas motions are also evident forindividual SiO maser components. The overallmorphology and evolution of the SiO emissiondeviates significantly from spherical symmetry. This

has important implications for models of pulsationkinematics and mass-loss in the near-circumstellarenvironments of Mira variables.

As in Hollywood, we are perfectionists when it comesto our art. The production of the TX Cam movie hasbeen a project long in the making and is clearly farfrom complete. A movie of all epochs is under con-struction and will be followed by further analysis ofthis rich and complex VLBA data set.

Reference:Diamond, P. J. & Kemball, A. J. 2003, ApJ (in press).


Philip Diamond (Jodrell Bank Observatory)Athol Kemball (NCSA/Univ. of Illinois at

Urbana-Champaign)

The Most Detailed Picture Yet of an Embedded High-mass YSO

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Distribution and proper motion of v=1 and v=2 SiOemission associated with Orion KL source“I” observedwith the VLBA. (top left) Integrated intensity. Thebrightest emission is coded red. (top right) Flux weightedmean velocity. Colors code Doppler shift. Continuumemission at λ=7mm, mapped with the VLA (Menten &Reid, private communication), is shown as color con-tours. Registration is accurate to 0.01". (bottom left) Asubsample of proper motions observed over 4 months.Cone lengths reflect 3D velocity. Aspect indicatesinclination with respect to the line of sight. Green conesindicate Doppler velocities within 5 km s-1 of the sys-temic velocity. The tickmarks are spaced by 50 milliarc-seconds.

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January 2004 Press Release Issue 98

PRESS RELEASE: NOVEMBER 12, 2003

Despite Appearances, Cosmic Explosions Have Common Origin, Astronomers Discover

A Fourth of July fireworks display features brightexplosions that light the sky with different colors, yetall have the same cause. They just put their explosiveenergy into different colors of light. Similarly,astronomers have discovered, a variety of bright cosmicexplosions all have the same origin and the sameamount of total energy.

This is the conclusion of an international team ofastronomers that used the National Science

Foundation's Very Large Array (VLA) radio tele-scope to study the closest known gamma-rayburst earlier this year.

"For some reason we don't yet understand, theseexplosions put greatly varying percentages oftheir explosive energy into the gamma-ray por-tion of their output," said Dale Frail, of theNational Radio Astronomy Observatory (NRAO)in Socorro, NM. That means, he said, that bothstrong and weak gamma-ray bursts, along withX-ray flashes, which emit almost no gammarays, are just different forms of the same cosmicbeast. The research team reported their results inthe November 13 issue of the scientific journalNature.

The scientists trained the VLA on a gamma-rayburst discovered using NASA's HETE-2 satellitelast March 29. This burst, dubbed GRB 030329,was the closest such burst yet seen, about2.6 billion light-years from Earth. Because ofthis relative proximity, the burst was bright, withvisible light from its explosion reaching a levelthat could be seen in amateur telescopes. As theburst faded, astronomers noted an underlyingdistinctive signature of a supernova explosion,confirming that the event was associated with thedeath of a massive star.Artist's Conception of Twin Jets in Energetic Cosmic Explosion

Credit: Dana Berry, SkyWorks Digital

An excerpt from the press release by Dave Finley.For the complete article go to

http://www.nrao.edu/pr/2003/grbtwinjet/

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ATIONAL ADIO O January 2004 Newsletter Issue 98O January 2004 Newsletter Issue 98 Groundbreaking for...

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