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Tenth Annual SummerStudents InvasionDavid Soderblom, drs@stsci.eduThis year was the tenthanniversary of the Institute’sSummer Student Program. For2002, we received about 100applications from students in the U.S.and abroad. Of these, we selected17 undergraduates and 2 high schoolseniors from the US and 6 foreigncountries to come to the Institute for asummer of astronomical research.Each student is assigned to amember of the scientific staff, whosupervises their research activities andmentors them. The students spend 10weeks at the Institute, where eachworks closely with staff astronomersand meets other students from differentbackgrounds with similar motivations.Their supervisors focus their attentionon productive research activities for anintensive period, usually involvingHubble observations. The results aremutually beneficial. Indeed, many oftoday’s front-rank astronomers hadsimilar opportunities during their collegeyears to help guide their early careerchoices. The research experience andthe encounter with an observatoryare also helpful when applying tograduate schools.The Institute’s research funds—the Director’s Discretionary Fund andstaff research grants—support theSummer Student Program.We will post information about the2003 Summer Student Program at http://www.stsci.edu/stsci/summer.shtmlshortly after December 1, 2002. Ω2002 Summer Students at STScINameSchoolInstitute SupervisorTiffany BordersSonoma State U.Keith Noll & Lisa FrattareJoseph ConverseColgate U.Claus LeithererCorey DowU. OregonPaul GoudfrooijHector GaluéMonterrey Inst. of Tech.Nolan Walborn & Jesus MaizPeter HuggerVirginia Military Inst.Massimo StiavelliHeather KnutsonJohns Hopkins U.John MacKentyKatarina KovacU. BelgradeSangeeta MalhotraAndrew LevanU. LeicesterAndy FruchterWladimir LyraFederal U. of Rio De JanieroDaniella CalzettiPavel MachalekUniversity College LondonKen SembachNatalie MintzU. WashingtonLetizia StanghelliniAlan O’ConnorLinganore HS, Frederick, MDDuccio MacchettoShannon PatelCornell U.Massimo RobbertoLeda PintoFederal U. of Rio de JanieroClaus LeithererAviva PresserUCLAMelissa McGrathAndre QuestelWoodlawn HS, Baltimore, MDAnton KoekemoerKristen ShapiroWilliams CollegeRoeland van der MarelElspeth SuthersU. WashingtonTorsten BoekerStefania VaranoU. BolognaDuccio Macchetto & Bill SparksFigure 1: Participants in the 2002 Summer Student Program. Front row: left to right: Peter Hugger, HectorGalué, Tiffany Borders, Shannon Patel, Katarina Kovac, Stefania Varano, Natalie Mintz, Lauren Rosenblatt (intern),Kristen Shapiro, and Leda Pinto. Back row, left to right: Alan O’Connor, David Soderblom, Elspeth Suthers,Pavel Machalek, Heather Knutson, Joseph Converse, and Andrew Levan. 4

ACS Begins Cycle 11Science OperationsMark Clampin, clampin@stsci.eduAdvanced Camera for Surveys (ACS) is now into the full swing of Cycle 11 science. We completedall the Servicing Mission Orbital Verification (SMOV) programs successfully, several weeksearly. ACS has now exercised every primary science capability, and its performance continuesto meet or exceed pre-launch expectations. General Observers (GOs) interested in examiningthe performance of ACS can download processed images from the ACS Early ReleaseObservations program and data from the Great Observatories Origins Deep Survey (GOODs) program.(http://archive.stsci.edu/hst/acsero.html, http://www.stsci.edu/ftp/science/goods/).The last major mode of ACS to be commissioned during SMOV was the coronagraphic mode in theHigh Resolution Camera (HRC). Initial SMOV test programs resulted in some changes to the targetacquisition apertures to optimize the placement of the target on the 1.8 and 3.0 arcsec occulting spots.Following these changes, we executed the SMOV calibration programs to exercise the coronagraph.The scattered light profiles obtained with these programs confirm that the coronagraph is behavingaccording to the design specifications.In Figure 1 we show the derived coronagraph contrast ratios for the 1.8 arcsec occulting spot. Itdemonstrates that the ACS coronagraph achieves a factor of ten suppression of the Hubble pointspread function (PSF). Optimal subtraction of the PSF gains two additional orders of magnitude.Detailed analysis of the SMOV programs has shown that commanding changes to coronagraphicimaging and target acquisition procedure can improve repeatability of the PSF subtraction. We willmake these changes and advise the PIs of coronagraphic GO programs accordingly once the capabilityis available for science observations.In addition to the completion of SMOV, the ACS Instrument Group has produced a number of calibration products from SMOV programs to update pre-launch reference files. The set of flat fields for 13Wide Field Camera (WFC) filters equalize the photometry of a given star to 1% (one sigma) for anyposition in the field of view. We are delivering a corresponding set of files for the High ResolutionChannel (HRC). We have made the corresponding updates to the Synphot reference files, so thatpipeline processing and the ACS exposure time calculators now use throughput tables based on measurements from SMOV photometric programs. We also incorporated into the geometric distortion reference file (IDCTAB) a distortion solution delivered by the Investigation Definition Team, which exceedsthe goal in the ACS Instrument Handbook. It employs a fourth order polynomial, which required a corresponding change in the PyDrizzle software. As ACS operations transition from SMOV to the Cycle 11calibration plan, we will describe new results in Instrument Science Reports, and incorporate them intoreference files. We will also provide updates to the GO community by means of the ACS SpaceTelescope Advisory Newsletters. The forthcoming HST Calibration workshop will also feature many presentations regarding the calibration of ACS. (http://www.stsci.edu/stsci/meetings/cal02/). ΩFigure 1: Contrast ratiosfor the ACS coronagraphobtained from F435W andF814W images. The plotshows ratios for directimaging, coronagraphicimaging, and the resultsof an optimum comparisonstar subtraction (CourtesyJ. Krist). 5

NICMOS RecommissionedMark Dickinson, med@stsci.eduThe Near Infrared Camera and Multi-Object Spectrograph (NICMOS), Hubble’s window on theinfrared universe, became inoperative in 1998, after Cycle 7, when its cryogens wereexhausted. In the summer 2002 issue of the Newsletter, Keith Noll described the installationand successful activation of the NICMOS Cooling System (NCS), which has brought NICMOSback to life as a working science instrument. Indeed, all indications are that NICMOS isfunctioning beautifully and seems an even better instrument than it was in Cycle 7.The NCS is maintaining the detector temperatures very stably at the programmed set point of77.1 K. This is excellent news for instrument calibration, since many of the detector properties dependstrongly on temperature. The new operating temperature is 15K warmer than that in Cycle 7, whichhas two major consequences for the detector. First, the linear dark current is about three times higherthan it was in Cycle 7, with values of 0.1 to 0.15 e-/s/pixel. Fortunately, a ‘bump’ of highly elevated darkcurrent, which was observed during end-of-life warm-up in Cycle 7, has not reoccurred. Therefore,the dark current is rarely, if ever, a limiting factor for observational sensitivity. However, there aresignificantly more hot pixels peppering the images than before.The detector quantum efficiency is higher at the warmer temperature, by as much as 80% at1 micron, 40% at 1.6 micron, and 20% at 2.2 micron. Moreover, the ‘flatness’ of the flat fields hasimproved, with smaller peak-to-valley excursions. Both of these changes are a substantial bonus forNICMOS observers, providing higher signal-to-noise ratio in a given exposure time and more uniformsensitivity over the field of view. As expected, the linear dynamic range is about 10% lower than inCycle 7. The ‘shading’ pattern, a noiseless but highly structured bias term, is significantly different thanin Cycle 7 and somewhat different from end-of-life predictions. Nevertheless, it appears to be stableand subject to calibration. Preliminary analysis of the thermal background at wavelengths longer than1.8 micron indicates no changes relative to Cycle 7.Another thing that has not changed since Cycle 7 (unfortunately) is the persistent afterglow fromthe particle bombardment as the telescope passes through the South Atlantic Anomaly (SAA). Thisafterglow produces a blotchy pattern of spatially correlated, non-Gaussian ‘noise’ (really signal), whichgradually decays during the subsequent orbit, and which can limit sensitivity for faint-object imaging. InCycle 11 operations, we are experimenting with methods to ameliorate the effects of afterglow. Wenow schedule short dark exposures after the telescope emerges from the SAA and before NICMOSscience observations. These ‘post-SAA darks’ are automatically delivered to users retrieving sciencedata from the archive. Early experiments indicate that proper scaling and subtraction of these darksfrom subsequent science exposures may partially suppress the afterglow signal and improve the noisecharacteristics of affected images. The Institute’s NICMOS group will continue to experiment with thisapproach, and, if it appears to hold promise, will develop software tools to aid users in applying suchcorrections to their own data.The execution of NICMOS programs from the Servicing Mission and Orbital Verification (SMOV) period,as well as the early calibration program, is almost complete. Regular calibration observations havestarted. The final SMOV program was the coronagraphic performance test. The Institute’s NICMOSgroup is presently analyzing the SMOV data and making calibration reference files for use in the dataprocessing pipeline.NICMOS General Observer science began on 13 June, 2002, with the execution of a visit fromprogram 9352 (PI: Riess) to observe a supernova at cosmological distances. At present, observers whoretrieve Cycle 11 NICMOS data from the archive will receive images processed using old, Cycle 7reference files. These (not surprisingly) yield unsatisfactory results, and users will certainly wish toreprocess their data when the new reference files are available. This can be accomplished easily byretrieving the data again, which will be automatically reprocessed by the NICMOS On-The-FlyReprocessing system, which was described in an article in the winter 2002 issue of this 02/winter 02.pdf).We are in the process of updating the NICMOS Instrument Handbook to describe the instrumentbehavior under NCS operations. Please consult the Institute’s NICMOS web pages for information as itbecomes available. (http://www.stsci.edu/hst/nicmos). Ω 6

James Webb SpaceTelescope (JWST) NewsRoelof de Jong, dejong@stsci.edu, and Marcia RiekePrime Contractor SelectedOn September 10, 2002, NASA announcedthe selection of TRW as the primecontractor to build Next Generation SpaceTelescope (NGST), which NASA renamedthe James Webb Space Telescope (JWST), namedafter James E. Webb, NASA’s second administrator.Figure 1 shows the TRW design for JWST, whichhas a 6-meter deployable primary mirror comprised ofthree hinged segments, each of which consists ofhexagon segments, in the manner of the Kecktelescopes. Under the terms of the contract, which isvalued at 824.8 million, TRW will design andfabricate the observatory’s primary mirror andspacecraft. TRW also will be responsible for integratingthe science instrument module into the spacecraft,performing the pre-flight testing, and checking out theobservatory on orbit.James WebbFigure 1. The recently selected TRW design for theWhile he is best known for leading NASA duringJames Webb Space Telescope, formerly known as thethe Apollo program of human landings on the Moon,Next Generation Space Telescope.James Webb also initiated a vigorous space scienceprogram at the agency, which conducted more than75 launches during his tenure, including America’s first interplanetary probes. Less widely knownis Webb’s advocacy—as early as 1965—of a large space telescope, which became the HubbleSpace Telescope.Webb favored strengthening NASA’s core of scientists and engineers with outside participantsto ensure the success of science missions. Today the Space Telescope Science Institute is oneembodiment of this idea. In 1998, NASA selected the Institute to manage the science program for thenew space telescope.Science and Instrument Teams SelectionOn June 20, 2002, NASA announced the selection of several of the science and instrument teamsfor JWST. NASA selected a team led by the University of Arizona to build the Near-Infrared Camera(NIRCam). Marcia Rieke is Principal Investigator (PI) of this team.NASA chose the U.S. portion of the U.S./European team that will construct the mid-infraredinstrument (MIRI). The members of this team are Dr. George Rieke (Team Lead, University of Arizona),Dr. Thomas Greene (NASA Ames Research Center), and Dr. Margaret Meixner (University of Illinois,soon moving to the Institute). They will oversee the construction of MIRI in collaboration with scientistsand engineers from the Jet Propulsion Laboratory, led by Dr. Gene Serabyn, and the European MIRIConsortium, led by Gillian Wright (UK Astronomy Technology Centre).NASA also selected several scientists to serve on the JWST Science Working Group (SWG) withthe principal observatory and instrument scientists. (See Table 1, page 8.) The SWG will provideguidance on the science goals and capabilities of JWST during the development of the telescope. Thefirst meeting of the SWG was scheduled for September 24-25, 2002, at the Institute. The agendatopics included the SWG charter and organization, JWST Project organization and status,status of individual science instruments, roles and plans of the Institute, and an update of the JWSTscience requirements.NIRCam ProposalJWST needs a sensitive near-infrared camera to achieve its goal of being the‘First Light Machine’ by imaging the first light sources in the distant, earlycosmos. To achieve this goal, this camera, NIRCam, should be capable ofContinuedpage 8 7

detecting 1 nJy point sources in a 100-hour integration (an integration time similar to the Hubble DeepFields). The NIRCam must also enable a host of other projects, like studying the course of galaxyevolution from the earliest luminous objects to present-day galaxies, the process of star formation inour own galaxy, and the nature of planets around other stars. The design of NIRCam must be optimizedto support these observations as well as all the other programs outlined in the Design ReferenceMission. (http:// www.stsci.edu/ngst/science/drm)Marcia Rieke’s team developed the NIRCam design incollaboration with Lockheed-Martin’s Advanced TechnologyCenter, COM DEV Space, and EMS Technologies. Table 2NGST Science Working Groupsummarizes NIRCam’s capabilities as proposed, which the teamwill bring into accord with the prime contractor’s telescopeNameInstitutionPositiondesign. In addition to the listed science capabilities, NIRCam alsoincludes wavefront sensing capabilities to help align the primaryJonathan GardnerNASA/GSFCDeputy Project Scientistmirror segments of the JWST.Matt GreenhouseNASA/GSFCISIM Project ScientistThe proposed design of NIRCam consists of four modules thatcan be used in parallel, two broad- and intermediate-bandHeidi HammelSpace Science InstituteInterdisciplinary Scientistimaging modules, and two tunable filter imaging modules, eachwith a 2.3 x 2.3 arcmin field of view. The two identical imagingJohn HutchingsDominion Astrophysical Obs. CSA Project Scientistmodules have a short and a long wavelength channel to takePeter JakobsenESA/ESTEC/ESANIRSpec Science Representativeimages simultaneously in light split by a dichroic at about2.35 µm. The short wavelength channels are sampled atSimon LillyU. of TorontoInterdisciplinary Scientist4096 x 4096 pixels, the long wavelength channels by 2048 x 2048pixels. The tunable filter imaging modules have a resolving powerJonathan LunineU. of ArizonaInterdisciplinary Scientistof about 100. One tunable filter module is optimized for wavelengths from about 1.2 to 2.5 µm, the other from 2.5 to 4.5 µm.John MatherNASA/GSFCNASA Project ScientistThe design has coronagraphs in all modules.Mark McCaughrean Astrophysics Inst. Potsdam Interdisciplinary ScientistFigure 2 (page 9) shows one of the tunable filter modules.The entire NIRCam design is compact like this module due toGeorge RiekeU. of ArizonaMIRI Lead Scientistrefractive camera optics. Figure 2 also shows one of NIRCam’sdual filter wheel assemblies—one wheel for filters and one forMarcia RiekeU. of ArizonaNIRCam Principal Investigatorpupils. The Canadian Space Agency will provide the tunable filtersMassimo StiavelliSTScIInterdisciplinary Scientistand filter wheels, proposed by the team to be build by EMSTechnologies and COM DEV Space, respectively.Peter StockmanSTScISTScI Project ScientistThe NIRCam team’s science program has threecomponents: a deep extragalactic survey, observations of starRoger WindhorstArizona State U.Interdisciplinary Scientistformation under varying conditions in the Milky Way, and a studyGillian WrightU.K. Astronomy Tech. Ctr ESA MIRI Science Representativeof circumstellar material in disks and planets. The team will useNIRCam’s tunable filters and coronagraphic modes extensively toaccomplish these science programs.The heart of the galaxy formation program is a deep survey using 50,000 second exposures in sixfilters and a 100,000 second exposure in the 4.4 µm filter. The detection limits are indicated inFigure 3 (page 10). While the broadband survey uses the two imaging modules, the tunable filtermodules will carry out an emission-line survey of the adjacent sky. Repeating the exposures six monthslater, when the field will have rotated by 180 degrees due to JWST’s orbital motion around the Sun,will yield emission line data on the original broadband fields and vice-versa.JWSTfrom page 7Table 1.Table 2. NIRCam CapabilitiesWavelength RangeSpectral Resolutions0.6 - 5.0 µmSelection of R 4 and R

F all 2002 VOL 19 ISSUE 04 Space Telescope Science Institute Duccio Macchetto, macchetto@stsci.edu, and Robert Williams, wms@stsci.edu Science Opportunities for Hubble Cycle 12 STScI-PRC02-11c, an image of the center of the Omega Nebula taken by the newly installed ACS aboard NASA's Hubble Space Telescope. W e are preparing for Cycle 12 amidst the excitement of early