The making of the Chandra X-Ray Observatory: Theproject scientist’s perspectiveMartin C. Weisskopf1

National Aeronautics and Space Administration/Marshall Space Flight Center, Huntsville, AL 35805

Edited by Harvey D. Tananbaum, Smithsonian Astrophysical Observatory, Cambridge, MA, and approved January 22, 2010 (received for review December16, 2009)

The history of the development of the Chandra X-Ray Observatory is reviewed from a personal perspective. This review is necessarily biasedand limited by space because it attempts to cover a time span approaching five decades.

historical perspective | x-ray astronomy

It is sobering forme to realize that therearescientistswhoareworkingwithdatafrom this truly great observatory whowere not even born when the founda-

tion for what is now the Chandra X-RayObservatory was laid. Thus, it may surprisemany to know that the beginning was suc-cinctly and accurately outlined in a researchproposal that Riccardo Giacconi and col-leagueswrote in 1963, amere9months afterhe and his team’s discovery of the first ex-trasolar x-ray source Scorpius X-1. As im-portant, the data from this rocket flightalso indicated the presence of the “diffusex-ray background.” Fig. 1 illustrates theshowpiece of this insightful proposal. Itshows a ≈1-m diameter, 10-m focal length,grazing-incidence x-ray telescope. Thetelescope was of sufficient area and angularresolution to determine the nature of theunresolved x-ray background. We all oweRiccardo an enormous debt of gratitudefor his insight, leadership, and, in my case(and I suspect formany others), inspiration.The resemblance between the early

conceptual design shown in Fig. 1, andChandra is no accident and is of im-portance in considering the way we (thescientific community) design our missions.Chandra was based only on achieving itsscientific requirements, principally to beable to resolve the faint backgroundsources. Chandra was not built on flying“what we can do.” Neither in 1963 nor,indeed, in 1976—when Riccardo andhis Co-Principal Investigator HarveyTananbaum submitted their unsolicitedproposal “For the Study of the 1.2Meter X-Ray Telescope NationalObservatory”—did one actually know howto build the subarc-second telescope re-quired to meet the scientific objectives. Ifeel it is important for one to know thatthese objectives were never compromisedduring the entire 23-year development,measured from the submission of thisproposal to the launch in 1999. Nor didthey lose their relevance during this time.This is in contrast to many [but not all(e.g., the Wide Field X-Ray Telescope)]missions, which suffer from what I call

“cost-credibility paranoia,” wherein onecan only convince others of the cost reli-ability of the mission if one has essentiallyalready built it. In too many cases, I feelthis approach has forced one to com-promise scientific objectives and to adopta “we will build it, you will use it” ap-proach to science. In these cases, too oftenare the scientific requirements adjusted tobe compatible with the existing technol-ogy, as opposed to driving the technology.The approach is not terrible, becausemissions such as the Rossi Timing X-RayExplorer have had, despite outdatedtechnology, a high measure of success.Nevertheless, Chandra is an outstandingexample of the power of the science-driven approach.

The proposal that Riccardo and Harveysubmitted in 1976 drew attention at theNational Aeronautics and Space Admin-istration (NASA) headquarters, which theninitiated a competition among the NASAcenters to establish where such a missionmight best be accomplished. In reaching adecision, NASA considered such factors asexpertise, experience, manpower avail-ability, and facilities. The Marshall SpaceFlight Center (MSFC) teamed with theSmithsonian Astrophysical Observatory(SAO), the Jet Propulsion Laboratory

Fig. 1. Drawing from the 1963 proposal.

Author contributions: M.C.W. wrote the paper.

The author declares no conflict of interest.

This article is a PNAS Direct Submission.1E-mail: martin.c.weisskopf@nasa.gov.

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teamed with the California Institute ofTechnology, and the Goddard Space FlightCenter (GSFC) teamed with GSFC sci-entists in vying for the mission. I joinedNASA in 1977, after the MSFC wasassigned the responsibility for the mission.I did this with the understanding thatProject Science was to be more than asingle person and that the local projectscience team would be further supple-mented by the group at the SAO, whichbecame known as the Mission SupportTeam (MST). There can be no questionthat the outstanding success of Chandra isattributable, in no small part, tothese arrangements.The first Science Working Group of

what was then called the Advanced X-RayAstrophysics Facility was chaired by Ric-cardo. I served as Vice-Chairman. Othermembers and their affiliations were asfollows: A. Opp (NASA headquarters; exofficio), E. Boldt (GSFC), S. Bowyer(University of California, Berkeley),G. Clark (Massachusetts Institute ofTechnology), A. Davidsen (The JohnHopkins University), G. Garmire

(California Institute of Technology),W. Kraushaar (University of Wisconsin,Madison), R. Novick (Columbia Uni-versity), S. Shulman (Naval ResearchLaboratory), H. Tananbaum (SAO), A.Walker (Stanford University), K. Pounds(Leicester University), and J. Trümper(Max Planck Institut fürExtraterrestriche Physik).The peculiar name of the project, an

“Advanced X-Ray Astrophysics Facility”(AXAF), was the inspiration of the NASAAssociate Administrator at the time. Hedid not want to use the word “telescope”in describing a future program, becauseCongress had recently approved atelescope—what is now known as theHubble Space Telescope (HST).1979 saw the launch of the Einstein

Observatory and its subsequent astoundingimpact on astronomy and astrophysics,namely, that all categories of objects fromcomets to quasars were x-ray sources andthat study of their x-ray emission providescritical insights into such factors as emis-sion mechanisms and evolution scenarios.This, in turn, led to the report of theAstronomy Survey Committee “Astron-omy and Astrophysics for the 1980s,”which recommended an AXAF as thenumber one priority for large spaced-based missions. The recommendation wasmore profound than one might imagine,because there was only one x-ray astron-omer (George Clark) on the committee.Despite this superlative recommendation,it would take almost two decades beforeChandra was launched. Although therewere numerous reasons for this slow ad-vance, and I am oversimplifying, Chandraappeared to need to wait its turn while theHST was being developed. We see thispattern reemerging as the InternationalX-Ray Observatory appears to need toawait the completion of the James WebbSpace Telescope (JWST). A famous NobelPrize winner has referred to the apparentdelays in some programs caused by finan-

cial overruns and technical problems ofother missions as “the punishment of theinnocent,” in a recent white paper to thecurrent Decadal Survey.1983 saw the release of the announce-

ment of opportunity for the first set ofinstrumentation (the “first set” becausethe AXAF was envisioned as being serv-iceable at that time). Experiment selectiontook place in 1985, and a second ScienceWorking Group was formed, which Ichaired and whose members and arepictured in Fig. 2.The selected instruments included the

Advanced Camera for Imaging Spectro-scopy(ACIS); theHigh-ResolutionCamera(HRC); the Low-Energy TransmissionGrating (LETG); the High-Energy Trans-mission Grating (HETG); the Focal-PlaneCrystal Spectrometer, which was removedduring a descoping exercise in 1988; and theX-Ray Spectrometer, which was moved toa mission named the AXAF-Spectroscopy(AXAF-S) in 1992 before cancellation ofthe AXAF-S by Congress in 1993.In addition to pursuing mirror and

detector technology development duringthe 1980s, many of us became salesmen andbrochure writers to gain full support for theprogram at NASA and in Congress. I willnot speak here of the heroic role played bythe Director of our science center, HarveyTananbaum. There can be no question thatwe all owe him a huge debt of gratitude. Ofcourse, Harvey was not the only one whohelped to create this program. Others, suchas Charles Pellerin and Arthur Fuchs at

Fig. 2. The second ScienceWorking Group. Left toright: A. Wilson [Interdisciplinary Scientist (IDS)], A.Fabian (IDS), J. Linsky (IDS), H. Tananbaum (head ofthe MST and ultimately Director of the ChandraX-Ray Center), A. Bunner (ex officio), S. Holt [X-RaySpectrometer Primary Investigator (PI)], M. Weis-skopf (Project Scientist), R. Giacconi (IDS), A.Brinkman (LETG PI), S. Murray (HRC PI), G. Garmire(ACIS PI), L. van Speybroeck (Telescope Scientist), C.Canizares (HETG/Focal-Plane Crystal SpectrometerPI), and R. Mushotzky (IDS).

Fig. 3. A page from the AXAF brochure of 1985.

Fig. 4. The gold-coated TMA.

Fig. 5. The XRCF at the MSFC. The building to theleft houses the x-ray sources, filters, and mono-chromators. In the building on the right is thelarge thermal vacuum chamber, at a distance of525 m from the source building. The chamberaccommodates the Chandra 10-m focal length andfull illumination of the 1.2-m-diameter optics.

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NASA headquarters and our industrialallies, also played a significant role. It mayseem inappropriate to some, but it is def-initely true that accomplishment of “bigmoney science” requires many skills. Thescientific excellence of the mission is nec-essary but, unfortunately not sufficient.One of our most successful endeavors inthis time frame was a brochure, a page ofwhich is illustrated in Fig. 3. A facing page(not shown) was designed for the in-telligent layman with an inset for ourcolleagues in the scientific community.The cartoons (one is shown in Fig. 3) werejokingly described as being aimed atNASA officials and members of Congress.Nevertheless, these cartoons were scien-tifically accurate and drew attention. Thebrochure not only won an artistic prize butmade a positive impression where it wasneeded. During this period, the SpaceStation was included as an ingredient inthe servicing of Chandra. For a number oftechnical and programmatic reasons, thistie-in soon disappeared.The late 1980s saw significant technical

progress. Two versions of what we calledthe “Technology Mirror Assembly”(TMA) were built and x-ray tested. Theassembly was composed of a single para-boloid-hyperboloid pair. The TMA was atwo-thirds scaled version of the mostchallenging (the innermost) AXAF mir-rors. At a two-thirds scale, the focal lengthbecame 6 m, which allowed for testing inthe existing X-Ray Calibration Facility(XRCF) at the MSFC. This facility hadbeen built to calibrate and test theEinstein x-ray optics.The TMA-1 was received July 27, 1985,

and the angular resolution was better than0.5 arc-seconds. However, to our chagrin,near-angle scattering attributable to mid-frequency errors had a negative impact onthe encircled energy. We had made thecardinal mistake of assuming that we neednot be concerned about errors on themillimeter-scale lengths that were theculprits, because we had not envisaged thatthe tools and processes we were usingcould introduce terms at those frequencies.Of course, we changed our technical

approach and removed these errors. TheTMA-2 was received January 6, 1989,and is shown in Fig. 4. The performanceof the TMA-2 was outstanding withrespect to all specifications and convincedus that the Chandra optics could be builtsuccessfully. It is interesting to knowthat, 20 years later, the TMA-2 is stillthe best x-ray telescope in the worldconsidering only angular resolution andencircled energy.Unfortunately, our critics did not

agree that we knew how to build the opticsand imposed on us the challenge ofmanufacturing the largest set (paraboloid-hyperboloid) of AXAF optics and dem-onstrating that the performance wouldmeet requirements. In his eagerness to

comply with this challenge, which wouldbecome a congressional mandate, theAssociate Administrator of NASA prom-ised that not only would we build and testthese mirrors using the optical metrologywe had verified by x-ray testing theTMA but that we would also perform thenecessary x-ray tests. Moreover, hecommitted us to accomplish this by thesummer of 1991. Unfortunately, the planand funds to enhance the existing XRCFwere not compatible with this schedule.NASA always seems to work best in a

crisis. The Director of the MSFC took itupon himself to manage the effort, whichmeant meetings once a week at 7:00 AM inhis office. Despite the early hour, theDirector’s intervention meant that all the

Fig. 6. The Verification Engineering Test Article.

Fig. 7. Performance of the Verification Engineering Test Article deconvolved to remove the effects of afinite-sized source at a finite distance and showing the on-orbit performance. The FWHM is 0.19 arc-seconds. Both the FWHM and the encircled energy were well within specifications.

Fig. 8. The SZ effect.

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resources of the center were available tous and without (most of) the usualbureaucratic holdups that occur when onewants to do something quickly. In myoral presentation, I showed a number ofslides that documented the developmentof the XRCF. The interested reader mayfind these on the Web. Fig. 5 shows thecompleted facility. The XRCF is currentlybeing used for visible-light cryogenic test-ing of the JWST beryllium mirrors.Fig. 6 shows the Verification Engineer-

ing Test Article, comprising the largestparaboloid-hyperboloid pair but uncoatedand uncut to their final length, and thusnot in the flight mount. Testing took placein 1991 and, after compensating for thefinite distance, the size of the x-ray source,and gravitational effects, produced theoutstanding result shown in Fig. 7.The project’s reward for this fantastic

effort was to have the following year’sbudget cut, necessitating another launchdelay. Despite all the progress, both in theoptics and concurrent instrument devel-opment, the launch of Chandra had beenpostponed at the pace of 1 year percalendar year for many years. Somethinghad to be done.The outcome of about a year of grueling

discussions and trade studies as to thedetails of the mission was to abandonservicing. To convince the powers-that-bethat servicing was not lurking in thebackground as a hidden variable, low-earthorbit was also abandoned. (It is interestingto contemplate the potential servicing ofChandra in the future when NASAdevelops vehicles capable of traveling tothe moon and Mars. It is also sobering to

realize that Chandra’s first servicing wouldhave been scheduled around the time ofthe Columbia accident.)Abandoning low-earth orbit had

numerous implications, some positive andsome negative. The negative aspectsincluded the sacrifice of two of the sixnested telescopes (as part of the weightreduction program necessitated by themuch higher orbit) and the loss of servicingand instrument replacement. Anotherconsequence turned out to be the estab-lishment and subsequent loss of theAXAF-S mission, which accommodatedthe extremely heavy x-ray calorimeter. Thismission was canceled in 1993 by Congress,which suggested that the calorimeter beflown on a Japanese mission, albeit withpoorer angular resolution than had beenplaned for the AXAF-S. One benefit fromthe redesign was the switch of the telescopecoating from gold to iridium. This changeretained the higher energy effective areadespite the removal of two mirrors.Another benefit was improved efficiencyfor observing afforded by the orbit. Thisorbit reduced both the debilitating effectsof occultation by the Earth and the amountof time spent in the radiation belts. Thetremendous decrease in the number ofoccultations of the sun by the Earth alsogreatly simplified the thermal design ofthe observatory.The very early 1990s also saw the

selection of the Chandra X-Ray Center(CXC), after an open competition for anorganization to serve as the interfacebetween the observatory and thecommunity. This early selection wouldguarantee that the organization could(and would) influence the design anddevelopment of Chandra and be in placein time to be challenged to analyze in-dependently data taken during x-ray cali-bration. Because Chandra would be muchmore scientifically powerful than previousmissions, it needed to be thoroughly andprecisely calibrated.An important and little known devel-

opment took place as part of the Chandraprogram in 1992. This marked the begin-ning of the efforts by John Carlstrom(California Institute of Technology at thetime) and Marshall Joy (Project Science atthe MSFC) to use millimeter-wave inter-ferometry as a tool to measure theSunyaev–Zeldovich (SZ) effect (Fig. 8),where photons from the 3° microwave

background are Compton-scattered by thehot x-ray-emitting electrons that pervadethe intracluster medium. The scientificproject of the Telescope Scientist, Leonvan Speybroeck, was based on the recog-nition that for relaxed clusters, where theassumption of hydrostatic equilibrium wasreasonable, one could simply combinex-ray measurements of the gas temper-ature and cluster size with SZ measure-ments to determine the distance. The onlydifficulty, even as late as 1992, was thatthe SZ measurements were extremelydifficult to accomplish. Thus, it was natu-ral for the Chandra program and theMSFC to sponsor this development.With the advent of the interferometric

techniques and the subsequent develop-ment of arrays specifically designed forthese observations, such as the Con-solidated Array forMillimeter AstRonoMy(Fig. 9) and the South Pole Telescope,Chandra spawned another scientific“industry” and was able to achieve Leon’sobjectives and more.In the fall of 1996, the flight mirrors,

fully cut, coated, aligned, and mounted(known as the High-Resolution MirrorAssembly) arrived at the MSFC for x-raytesting and calibration. X-ray calibrationwas extremely important for a number ofreasons. First, the calibration activitywould verify, beyond any doubt, that theoptics had been built (as it turned out) tomuch better than their specifications.Second, and more important, the per-formance characteristics of the optics andthe optics in conjunction with the flightinstruments were calibrated to variousdegrees of precision as called for in a hugecalibration requirements document pre-pared by the scientific participants. (Manyhave mistakenly thought that all Chandracalibration requirements were to be atthe 1% level. The 1% value is mistakenlyquoted out of context from the overall

Fig. 9. Consolidated Array for Millimeter AstRonoMy.

Fig. 10. Photograph of a typical daily meeting inthe conference room at the XRCF. Clockwise:hands of S. O’Dell (Project Science), S. Wolk (CXC),C. Jones (CXC), R. Carlsen (TRW), D. Jerius (MST),and the back of the head of D. Dewey (HETG).

Fig. 11. Lower row: Eileen M. Collins, MissionCommander; Michel Tognini, Mission Specialist.Upper row: Steven A. Hawley, Mission Specialist;Jeffrey S. Ashby, Pilot; Catherine (Cady) G. Cole-man, Mission Specialist.

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requirement of the observatory tocalibrate accurately).Additional benefits of calibration inclu-

ded providing a database of flight-likedata, and thus an early test of the PrincipalInvestigator’s and CXC’s ability to dealwith flight-like data. Additional benefitswere the camaraderie and friendship thatdeveloped as scientists, engineers, andmanagers from the various different teams(e.g., MSFC Project Science, SAO MST,HRC, ACIS, LETG, HETG, MSFC Proj-ect Management, MSFC Engineering,TRW, Ball Aerospace, Eastman Kodak)worked together “24/7” throughout thelonger than 6-month period (Fig. 10). Theexperience was a major contributor towardchanging people’s perception of eachother, particularly in becoming “we” asopposed to “us and them.”Subsequent to x-ray testing, the focal-

plane detectors went to Ball Aerospace inColorado for integration and testing intothe module that houses them and providesthe linear translations used both to switchinstruments and to provide focus adjust-ment. These mechanical drives, which we

worried about a lot before launch, havenow worked routinely thousands of timesthroughout the mission. This ScienceInstrument Module (SIM) was thendelivered to the TRW in California forintegration into the spacecraft (S/C) andfor system-level testing.System-level testing, both at the SIM and

S/C level, brought on a number of technicaland programmatic challenges. One ofmost notable was the failure of the vacuumdoor that protected the ACIS instrumentto open during the thermal vacuum test.A second involved compromised printedwiring boards that required the project todelay the launch by many months whilethe appropriate electronics were removedfrom the S/C, replaced, retested, andreintegrated. We all owe a large debt ofgratitude to Michael Hirsch at the TRWfor forcefully bringing this problem toeveryone’s attention.In the spring of 1999, the observatory

was delivered to the Kennedy Space FlightCenter for integration with the inertialupper stage (IUS) and subsequent inte-gration into the cargo bay of Columbia.The IUS is a solid-rocket two-stage enginethat would boost Chandra toward itspresent orbit. The combined Chandra-IUSsystem became the heaviest payload ever

launched by a shuttle. The activities sur-rounding the launch were themselves veryinteresting. The Commander of Columbiawas Eileen Collins, the first woman to holdsuch a position. She, along with her crew, ispictured in Fig. 11. Eileen drew a lot ofattention and special visitors. Not only didthe First Lady, Hillary Clinton, come tovisit but the singer Judy Collins wrote,composed, and then sang: “And we willfly beyond the sky. Beyond the stars,beyond the heavens. Beyond the dawnwe’ll carry on. Until our dreams haveall come true. To those who fly, we singto you.” Perhaps as important from ourperspective was the press’s attention toEileen. This attention minimized thenumber of times we were asked if thistelescope would have problems such asthe HST initially experienced. Of course,we could answer that the telescope hadbeen successfully tested and calibrated.Other notables at the launch included

Lalitha Chandrasekhar (Fig. 12), who reada poem she had composed and noted thatSubramanyan Chandrasekhar, after whomthe observatory is named, would not haveenjoyed all the fuss. The male modelFabio also attended under the falseassumption that he had been invited bythe astronaut Cady Coleman. The in-vitation had been jokingly issued in hername by her fellow crew members.It took three attempts to launch the

shuttle. These occurred just past midnighton the mornings of July 20, 22, and 23,1999. The successful launch was challeng-ing for the astronauts because of ahydrogen leak and an electrical short thattook place shortly after the rockets fired.The calmness of the astronauts throughthese major glitches was testimony totheir courage and ability. Placement into

Fig. 13. At the Chandra control center. Left toright: J. Olivier (Deputy Project Manager), C.Canizares (HETG PI), S. Murray (HRC PI), H. Ta-nanbaum (CXC Director), J. MacDougal (MSFCChief Engineers Office), and R. Schilling (TRWDeputy Project Manager).

Fig. 15. The full “first-light” image on the ACIS-S3 after aspect correction. The bright source indicatedby the red arrow is “Leon X-1,” a type 1 AGN at z = 0.3207.

Fig. 12. Lalitha Chandrasekhar with a model ofthe observatory.

Fig. 14. Raw image of “Leon X-1.” The data werenot yet corrected for S/C motion, and the detectorwas not yet at best focus.

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low-earth orbit was only the beginningfor us of many tense days before wecould be sure that the observatory wasworking properly. Just 8 h into the missionand after the successful deployment fromColumbia, we required the successfuloperation of the IUS. Although thissystem had an excellent track record, theprevious use of an IUS had failed, albeitfor reasons that we understood and wereconfident would not reoccur. Still, oneworried. Obviously, the IUS successfullyfired and placed the observatory near itsfinal orbit. Then followed the use ofChandra’s own propulsion system, whichwas fired five times over many days toachieve the final orbit. Of course, activa-tion and checkout were taking place inparallel. Perhaps the event that was mostintense was the opening of the door to theACIS in view of the previously mentionedfailure during testing. The ACIS teammade a number of technical and opera-tional changes to the door mechanismsand provided more robust opening proce-dures, but we were unsure that we reallyunderstood the root cause of the previousfailure. One can imagine that we were verynervous during the opening process.Fig. 13 shows a partial view of the controlcenter during the commissioning, and onecan see the concentration on people’sfaces during these times.The observatory was launched with

S3, the better of the two ACIS back-illuminated CCDs, at the prime focus.Which instrument to place at the focusduring launch was the result of much dis-

cussion. We wanted to assure a powerfulscientific mission in the event that, forsome reason, the SIM motions failed,thereby preventing changing instruments.On August 12, 1999, the last door pre-

venting the optics and the ACIS fromviewing the universe was opened. The true“first-light” Chandra image is shown inFig. 14. The raw ACIS image of thebrightest source on S3 told us, by in-spection (because the flux was con-centrated into a handful of AXIS pixels,each subtending 0.5 × 0.5 arc-seconds),that the observatory was operating moreor less as expected, even before establish-ing best focus. Of course, we now knowthat the observatory is performing as pre-dicted. The full S3 field is shown in Fig. 15.The bright source that we dubbed “LeonX-1” turned out to be a type 1 active ga-lactic nucleus (AGN) at a redshift of z =0.3207. The ubiquity of the AGN in x-rayimages was not a surprise but certainly aforerunner of the fabulous discoveriesthat Chandra was about to make.The next tasks in the commissioning

process were to test the aspect system andto determine the best focus for the ACIS-S.Our target was a bright AGN, selectedbecause we wanted a bright point source.Fig. 16 shows the image and highlightsthe discovery of an x-ray jet, an accidentalbut certainly exciting outcome. Moreover,the angular resolution of Chandra allowedthe use of these data to determine thebest focus. Another Chandra “test image”produced a fruitful scientific result. Thenow famous image of the Crab Nebula, itspulsar, and the remarkable structureshowing the shock produced by the pulsarwind was another spectacular result fromsuch a test.Now, we are celebrating 10 years of

outstandingly successful scientific researchwith this great observatory. There canbe no question as to its success, whethermeasured in terms as mundane as pub-

lications, citations, and PhD theses,for example, or more profoundly byproducing such results as the clarificationof the mechanism producing the x-rayemission from comets, the resolution ofthe diffuse background, the independentand confirmatory measures of theHubble constant, and constraining theequation of state of the universe. In 47years, we have been privileged to partic-ipate in the advancement of a disciplinethat has moved from discovery of a singleextrasolar x-ray source to the detectionof sources ≈10 orders of magnitudefainter. The smiles of those pictured inFig. 17 are as applicable today as theywere at the time one saw the earliestChandra images.Those interested in more information on

making the Chandra X-Ray Observatoryshould see the book by Wallace and KarenTucker (1).

ACKNOWLEDGMENTS. We all owe a debt of

gratitude to the many people who contributed

to Chandra’s success, including the US taxpayers,

who, through their government, have had the

courage and insight to foster such important

research.

1. Tucker W, Tucker K (2001) Revealing the Universe: The

Making of the Chandra X-Ray Observatory (Harvard

Univ Press, Cambridge, MA).

Fig. 16. Image of Parkes 0637-752 and its x-ray jet.

Fig. 17. Observing the official first light on Au-gust 19, 1999, at the control center. Right to left:M.C. Weisskopf, T. Aldcroft, C. Grant, H. Ta-nanbaum, R. Brissenden, M. Bautz, M. Freeman, F,Baganoff, and K. Gage.

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