astronomer’s proposal tools
TRANSCRIPT
SPACE TELESCOPE SCIENCE INSTITUTE
NewsletterHighlights of this Issue:• Grants Management System
— page 3
• NGST News— page 6
• IRAF and Python— page 19
March 2001 • Volume 18, Number 1
10Astronomer’s Proposal ToolsSteve Lubow, [email protected]
STScI is developing a newgeneration of proposalpreparation tools called
the Astronomer’s Proposal Tools(APT).These tools are based on theScientist’s Expert Assistant (SEA)project which began in 1997 at theAdvanced Architectures and Automa-tion Branch of Goddard Space FlightCenter. The APT aims to improve theproposal preparation process in orderto provide users with a more intuitive,visual, and interactive experience bymeans of state of the art technology.Another goal is to make these toolsgeneric so that they can be easilyshared for use in creating proposalpreparation systems by otherobservatories.
Tools that are currently underdevelopment are:
• The Visual Target Tuner (VTT) wasinitially released in June, 2000. Thistool displays HST apertures superim-posed on sky images (right). The VTTprovides capabilities to import skyimages, display primary and parallelapertures, rotate apertures, centroidobjects, specify excluded points andregions, display legal orientations,and display catalog overlays andobject information.
• The Starview/VTT tool will allowusers to graphically display thepointings and apertures for archivedHST exposures in the VTT. With thistool, users will be able to carry outduplication checks on observations thatthey display in the VTT.
• The Bright Object Tool will allowusers to check proposed observationsfor instrumental health-and-safety, aswell as science problems (such asbleeding). The tool will allow users todisplay the results graphically in theVTT or read the results in a table.
• Exposure time calculators will beenhanced to provide graphicaldisplays, such as exposure time as afunction of signal to noise.
• Spreadsheet-like editors will beprovided for users to enter proposal
Cycle 10Who got time on HST to do what ...
How the selection process worked ...
ApprovedPrograms
page 11
continued page 3
DIRECTOR’S PERSPECTIVE
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Steven Beckwith
Newsletter • Space Telescope Science Institute
Old data and new discoveries
We measure the success of the Hubble Space Telescope by its impact on scientific research and by its public impact.So we take pride when the two coincide, as they have recently in discoveries from the Hubble archive. Perhaps mostnoteworthy is that the two most recent discoveries of public acclaim came from old data, not new.
Joseph Dolan at Goddard Space Flight Center uncovered evidence for accretion onto a black hole by examining High SpeedPhotometer data nearly ten years old and applying a technique to search for the signature of matter disappearing beyond an eventhorizon (Dolan, J. Bull. AAS, 197-118.05). The signature in this case was a series of pulses emitted by clumps of gas as theybreak away from the innermost stable orbit around a black hole – about 3 Schwarzschild radii out – and spiral in along a set oforbits with decreasing radii. As the gas streams away from us in its orbit, its emission is redshifted and dimmed. As it circles andcomes toward us, it becomes blueshifted and brightens. Each successive circle creates a pulse of decreasing magnitude, increas-ing width, and decreasing period until the gas descends below the event horizon and disappears without further trace. Thesignature is unique, because if the gas encountered a compact surface, such as that of a neutron star, the final pulse would end in aburst of energy as the gas came to a sudden stop.
Dolan searched for such pulse trains in observations of Cyg X-1, the first candidate black hole to come from early x-raytelescopes. He found two series that matched the characteristic shape and timing expected for gas going into a black hole of10 M
O. or so. This was the first time such a pulse train had been seen, and it lent impetus to further observations at x-ray wave-lengths, where the signatures should be even more pronounced (the signal to noise ratios of the old HSP data certainly needimprovement before this work is accepted by everyone). Dolan’s work found its way to the New York Times science section inJanuary of this year, once again stimulating public interest in astronomy.
Adam Riess and his colleagues (Riess et al. 2001, Ap. J., in press) added even more support for a non-zero cosmologicalconstant, the “dark energy” that accelerates the expansion of the universe, with their study of a high redshift supernova discov-ered by Ron Gilliland (Gilliland et al. 1999, Ap. J. 521, 30) in Hubble observations from 1997. SN 1997ff was identified in theHubble Deep Field early on, and it popped up in the deep infrared images of the Hubble Deep Field north by Rodger Thomspon’sNICMOS team. Because the images were taken in regularly spaced observations over a few months, it is possible to get informa-tion about the supernova light curve and the change in its spectral energy distribution just after peak brightness. Photometric dataon the host galaxy place SN 1997ff at a redshift of about 1.7, the highest redshift supernova ever seen.
Because it is very distant, this supernova emitted its light when the acceleration of the universe was just starting, and the effectof the dark energy should be small when comparing the supernova’s apparent brightness to its redshift distance. If the dark energydid not exist, and the light from less distant supernovae was affected by intergalactic extinction (gray dust) or an evolution in thecharacter of supernovae over cosmic times, SN 1997ff would have uncovered these effects since they would have changed thebrightness vs. redshift relationship in opposite ways to the dark energy. But the brightness of SN 1997ff is consistent with thedark energy interpretation and not the other effects, and Riess and his colleagues have provided compelling evidence that the darkenergy must be taken seriously.
Many of us suspect that data archives will play an increasingly important role in astronomy as the sizes of the archives grow.The National Academy’s Survey on Astronomy and Astrophysics, the decadal survey of 2000, recommended establishing aNational Virtual Observatory, linking together many data banks covering many wavelengths and instruments to enable archivalresearch on a scale far greater that what is presently possible. A Virtual Observatory will be a grand experiment. No one hasdemonstrated that archival research will be important enough to justify the expenditure – some tens of millions of dollars. Wehave already invested several billions of dollars to get the data, including Hubble, Chandra, and SIRTF in the space community,and Gemini, Keck, ALMA, and the VLT, to mention but a few on the ground. It would seem that investing a few percent of thecapital expenditures to enable future astronomers to mine the data is well worth the cost.
It is interesting is that the recent archival discoveries cited above are so important to their respective research fields. Thelikelihood of finding a high redshift supernova in a field the size of NICMOS (55 seconds of arc) during a few months observa-tion would seem to be very small unless the events are more common than we think. Many events may be more common than wethink; we will not know until we have surveyed the universe over time as well as wavelength and space. If we can discover thepreviously unknown but common events by combing through data taken for other purposes, archival research may be the mostefficient path to discovering new phenomena now that preliminary exploration of the spectrum has been done. The excitingdiscoveries from old data sets portend a bright future for old data.
Steven BeckwithBaltimore, March 26, 2001
March 2001
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STScI Electronic Grants Management SystemRay Beaser, [email protected]
The Space Telescope ScienceInstitute is pleased to an-nounce the implementation of
an electronic web-based grantsmanagement system. The system isbeing used to provide funding for U.S.astronomers associated with GeneralObserver and Archival Researcherprograms as well as all other programsadministered by STScI.
The main features of the system arethe electronic submission of budgets,performance reports, financial reports–including payment requests – and allother administrative actions such asno-cost extension and equipmentrequests. The system provideselectronic notification of grant awardsand amendments as well as real-time
access to proposal and grant statusinformation.
The system was implemented forCycle 10. The Grants AdministrationOffice contacted the AuthorizingOfficials (AOs) of each U.S. institutionwith a Cycle 10 investigator to activateinstitutional accounts. The AOs at eachinstitution enabled investigatoraccounts and assigned appropriateprivileges for various functions withinthe system.
With the exception of a few budgetsthat were submitted on paper, allCycle 10 General Observers andArchival Researchers submitted theirbudgets via the new electronic system.The Grants Administration Office iscurrently contacting the remainder of
our grantee institutions that have openHST grants to activate their accounts.As of July 1, 2001, the electronicsubmission of interim and finalfinancial reports will be required.
The Cycle 11 budget submissiondeadline is expected to be mid-February 2002. If an account has notbeen activated for your institution,please contact the Grants Administra-tion Office at the telephone number oremail address listed below.
Information about the new grantssystem is currently available atthe following web site:http://gms.stsci.edu. If you have anyspecific questions, please send e-mailto [email protected] or call410-338-4200.
information in a tabular manner.The editors will have capabilities forviewing and manipulating the data in aconvenient manner.
The APT will ultimately be acomplete and integrated system forproposal preparation which willreplace the current RPS2. The APTwill provide capabilities for develop-ing Phase 1 GO, Phase 1 Archival, andPhase 2 proposals.
In the short term, individual toolsare being released that operateindependently of each other. Theyassist in proposal preparation but donot directly generate a full proposal.We aim to release these tools on atimely basis. We hope to get feedbackfrom users. This feedback will play animportant role in guiding our efforts.Several tools have been released foruse in Phase 2 of Cycle 10.
APT from page 1
HST Recent Release: NGC 4013: A Galaxy on the Edge
The Hubble telescope has snapped this remarkable view of a perfectly "edge-on" galaxy, NGC 4013. This new Hubble picture reveals with exquisite detailhuge clouds of dust and gas extending along, as well as far above, the galaxy'smain disk. NGC 4013 is a spiral galaxy, similar to our Milky Way, lying some55 million light-years from Earth in the direction of the constellation UrsaMajor. Viewed face-on, it would look like a nearly circular pinwheel, butNGC 4013 happens to be seen edge-on from our vantage point. Even at 55million light-years, the galaxy is larger than Hubble's field of view, and theimage shows only a little more than half of the object, albeit with unprec-edented detail.
Image Credit: NASA and The Hubble Heritage Team (STScI/AURA)
Web Address: http://oposite.stsci.edu/pubinfo/pr/2001/07/
Newsletter • Space Telescope Science Institute
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Multi-Mission Archive at the Space Telescope Science Institute (MAST) NewsPaolo Padovani (on behalf of the MAST team), [email protected]
Hubble Data Archive Status
The Hubble Data Archive(HDA) contains, as of March1, 2001, 7.1 Tbytes of data.
The number of science datasets nowtotals more than 230,000. Archiveingest has averaged 3 Gbytes/dayin the past year, while the rate ofdata retrieval has been more than4 times that.
Literature links:from data to published papers
We have embarked on a project toallow archival researchers easy accessto MAST-based papers directly fromthe archive interface. This project iswell under way and actually completedfor some missions, so we describe herein some detail its implementation.
The MAST archive interfaces(accessible from the MAST main pageat http://archive.stsci.edu/mast.html)provide a list of datasets matching agiven query and also return variouscolumns with target parameters (e.g.,target name, coordinates, instrument,etc.). These now include a “Ref”column, which specifies the number ofpublished papers associated with thelisted proposal ID (HST) or image ID(other MAST missions). Clicking onan entry in this column (other than adash, which means that no papersreferencing the proposal/image ID areavailable) will display the list ofrelated papers including title, firstauthor, and journal reference. Thelatter follows the Astrophysics DataSystem [ADS] bibliography code(bibcode) and is also a link to the ADSAbstract Service, which provideselectronic access to the paper. (Notethat at present only refereed papersare included.)
ADS users performing literaturesearches can now do the opposite, i.e.,go from papers to data. A “Data” linkavailable in the ADS abstract page, in
fact, lists the MAST observationsassociated with a given paper andprovides a link back to MAST. Thistakes the user to two different webpages, depending on the mission. ForHST, ADS users enter MAST via theproposal page, which gives theproposal abstract, the list of relatedpapers, and a search output (up to 100datasets) for that proposal, with linksto preview files, and “mark” buttonsfor direct retrieval from the archive.For other MAST missions, a previewpage is available which displays a plotof flux versus wavelength, listsrelevant published papers, and allowsthe option of downloading the data ineither FITS or ASCII table format.
The level of completeness of thebibliographic entries varies with themission. For HST, the links includepapers published between 1991 and1997 and in 2000. Papers published in1998 and 1999 will be added verysoon. IUE, the ASTRO missions(HUT, WUPPE, UIT), BEFS1, andEUVE are complete through the year2000, and work is on-going onCopernicus papers (FUSE papers andpublications based on the otherORFEUS missions will be addedeventually).
The HST bibliography includes allpapers making original use of HSTdata including papers written both byobservers and archival researchers.These ‘original use’ papers areidentified by the STScI librarysearching all incoming journals forpapers that use HST data directlywithout citing prior usage of thosedata. For the non-HST bibliography,on the other hand, MAST staff andIUE staff member Pat Pitts attemptedto find all papers citing the use ofMAST data.
We invite you to use this newservice (and tell us about any paper wemight have missed!). As usual, sendany comments/questions/suggestionsyou might have to [email protected].
On-the-Fly Reprocessing(OTFR) and You
Around the beginning of April,2001, we will turn on a new “on-the-fly” system for archived STIS andWFPC2 data; archived NICMOS datawill be affected by this system as ofMay or June this year. Our “on-the-fly” reprocessing system will processdata from the telemetry productthrough conversion to a FITS file andfinally to instrument calibration. Thissystem will replace OTFC (On-The-Fly Calibration).
What does this mean to the HSTarchive user? Basically, the averageHST archive user will not seemany differences.
So why did we do it?“On-the-fly” processing in general
provides a better science product, ascompared to the original, first cutcalibrations. However, our OTFCsystem was cumbersome, with anextensive database change system, andOTFC could not handle data associa-tions with multiple files, such as thosefor NICMOS and ACS. By processingfrom the telemetry files with thecurrent pipeline software, we were ableto reduce the need for an extensivechange system and we will be able tohandle associations in a graceful way.
How will this system affect thearchive user?1) On-the-fly calibration of NICMOS,WFPC2, and STIS.
2) No “original” calibration files forthose instruments. We do not savethem anymore.
3) All requests for NICMOS, WFPC2,and STIS science data will includeboth the raw and calibrated FITS fileswith updated headers.
Any questions can be directed [email protected].
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StarView 6.1StarView 6.1, the newest version of
the StarView Java application, wasreleased in October, 2000. Weappreciate any and all suggestions!Send them to [email protected] is available for download athttp://starview.stsci.edu. Existingpersonal installations of StarView areupdated in situ, with your permission.If you access a centralized version ofStarView, notify your science softwaremanager. Future updates of both localand centralized installations will beautomated, with appropriate approvals.
We highlight some of theimprovements contained inVersion 6.1:• Data Retrievals of multiple datasetsare even easier: you can select themwith the mouse, shift-click to selectmultiple sets. Pressing the “mark”button marks all of the selecteddatasets for retrieval.
• Data Retrievals of HST datainclude the ability to save youraccount password, change yourpassword, change your mailingaddress (for tapes).
• The Help menu now includes ArchiveStatus, which for now links to the HSTDADS status page, as well as the HSTArchive Registration page, How-Tosand FAQs.
• The Qualifications Editor was re-written, so that it now behaves muchbetter. The layout of the QualificationsScreen was modified to be easier toread and use.
• Qualifications can be saved to diskand loaded either into another form(as long as the fields are consistent)or into the same form on another day(for repeated retrievals of verysimilar types.)
• Cross-qualification of coordinateswas improved: it now works fasterand has more versatile input formatswhich are controlled through thePreferences screen.
• System manager control of automaticupdates for centralized installations ofStarView.
Future improvements includegeneralizing the retrieval and archivedescription module to include all of theMAST missions and coordinatingStarView with the Visual Target Tunerfrom the Astronomer’s Proposal Toolsuite. Expanding the data domain toinclude all of MAST is the first stepneeded to make StarView usable as ageneral search interface for anyobservatory archive. StarView will bea completely configurable Javasearch interface.
Old StarView Versions Will No LongerBe Supported
The X-windows version of StarView(xstarview) and the antiquated “CRT”version of StarView (starview) wereturned off as of November 1, 2000.The old NCSA server which servesforms for these versions of StarViewwas removed to simplify maintenanceand Web security. All versionsnumbered 5.4a and earlier nolonger function.
SV_DADS_RETRIEVEThe stand-alone tool,
sv_dads_retrieve, which can be used inuser-written scripts to request datasetsdirectly from the HST archive facility(DADS), will continue to work.However, as DADS is revised, this toolwill have to be updated to stay apacewith the changes (that includeencryption conventions). Users of thisstand-alone tool should stay abreast ofthe tool’s update which will occur inphase with the archive transitionsplanned over the next year.
New Archive MediumLast fall the HST archive began
using a new archive medium, magneto-optical (MO) disks, to store HST data.We have started a process to move allof the science data from the oldmedium (12 inch Sony optical platters)onto the new MO disks. As of March1, 2001, we are about a third of theway done and estimate that it will takeabout a year or so to complete thisprocess. This transition should betransparent to users, who are still ableto access data from either medium.Your patience has been very muchappreciated during this transition timeas we gain experience with ournew system.Once this process is complete, weanticipate much faster retrieval timesas all data will be available in the newMO jukeboxes.
Improved Retrieval Times for IUE FinalArchive Extracted Data Files
The IUE Final Archive extracteddata files are those most frequentlyrequested from the MAST archive(other than HST and FUSE data). Toimprove retrieval times, the IUE Low-and High-Dispersion Merged Ex-tracted Image FITS Files (MXLO andMXHI respectively) have been copiedto disk on archive.stsci.edu allowingusers to retrieve these data much morequickly. As before, users may retrievedata either through the IUE WWWinterface or via anonymous ftp. Theremaining IUE files are still availablebut remain in a CDROM jukebox.Users requesting other IUE files(as well as UIT and BEFS data) mayneed to wait a few minutes to allowthe jukebox to retrieve and mount theCDROM.
MAST from page 4
Newsletter • Space Telescope Science Institute
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The Next Generation Space Telescope at the beginning of a new millenniumN. Panagia and H.S. Stockman
The Next Generation SpaceTelescope (NGST) is a large-aperture optical and infrared
telescope being designed to study theproperties of the first stars and galaxiesborn after the Big Bang and toelucidate the mysterious process of starand planet formation in our owngalaxy. The high spatial resolution andlow background provided by a largeaperture, passively cooled telescope inan L-2 orbit are essential for thesestudies. Compared to current orplanned observatories, NGST willhave unique advantages in imagequality field of view, low backgroundlight, and environmental stability.In particular, observations will belimited only by zodiacal lightbackground for near infrared wave-lengths less than 10 microns.
NGST will be a unique internationalfacility with contributions fromNASA, the European Space Agencyand the Canadian Space Agency. In therecent decadal survey of astronomyand astrophysics, sponsored by theNational Academy of Science (http://books.nap.edu/catalog/9840.htm1), NGSTwas ranked as the highest-priority, newinitiative for the next 10 years. Thisranking reflects both the excitingnature of NGST science and therecognition that NGST is technologi-cally within reach.
The NGST project is currently in thepreliminary design phase. Majorstudies of lightweight mirrors anddetector technology developments areunderway and show encouragingresults, and new focal-plane assem-blies for multi-object spectroscopy arebeing developed. Phase-A systemsarchitecture studies are underway byindustry consortia that include TRW,Ball Aerospace, Lockheed-Martin, andRaytheon Corporation.
NGST at launch minus 8 years: Meetingcost and schedule constraints
In the light of results from costingexercises for other NASA missions,
and in preparation for issuing Requestsfor Proposal (RFPs) for the NGSTprime contract in mid-2001, the NGSTproject has undertaken a detailed re-assessment of the design parameters.The principal goals are to get the mostobservatory capability per dollar and tolaunch in this decade. A major result ofthis exercise has been to relax therequirements on the diameter, arealdensity, and temperature of the primarymirror. A modest reduction in theaperture diameter can result in a stiffermirror that still meets the launchweight constraints for more than onelaunch vehicle while retaining amarkedly superior performance overall other telescopes. The illustrationbelow compares the amount of timeneeded to make an imaging surveywith a hypothetical 6.5m NGST, withHST, SIRTF, and a ground-based 8mtelescope. Moreover, allowing theprimary mirror to operate at a warmertemperature will permit active thermalcontrol using heaters. The stifferprimary will provide better, morestable image quality at lower cost thanother options. It will also enable muchmore complete verification of imagequality and control in ground testing,
reducing the need for a flight valida-tion experiment.
NGST will still carry three instru-ments: a visible/near-infrared (0.6 to 5microns) camera with a field of viewof 10 to 20 square arcminutes, a near-infrared multi-object spectrograph, anda mid-infrared camera/spectrograph.It should be stressed that conceptsfor NGST are still in development, andit will be up to the prime contractorsto propose an observatory they canbuild within the cost and scheduleconstraints.
Interim Science Working GroupReplaces ASWG
The NGST Ad Hoc ScienceWorking Group (ASWG) has beenproviding science guidance since itscreation in September 1997. TheASWG was responsible for construct-ing the Design Reference Mission(DRM, http://www.ngst.stsci.edu/drm),which has been used heavily as a toolin design trade studies. The ASWGalso made recommendations on theNGST instrument complement, takinginto consideration the NASA, ESA,and CSA instrument concept studies,
NGST = 1
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the NGST science goals, andthe expected advances in groundbased facilities.
The ASWG has recently undergonea metamorphosis into the InterimScience Working Group (ISWG). Thisgroup will function through theformulation phase (Phase A/B), untilthe instrument Announcement ofOpportunity is released. The ISWGwas selected in September 2000, fromover 100 highly qualified applicants.The resulting committee includesobservers, theorists, and instrumentbuilders and reflects both the interna-tional nature of the project and thediverse scientific goals and capabilitiesof the observatory. The ISWG willwork in collaboration with the NGSTProject, NASA Headquarters, and theastronomical community to provideinput during the formulation phase ofNGST. The ISWG will help provide
astronomy community input onquestions relating to the sciencemission of NGST and will helpdisseminate information about NGSTto the community.
Technology Development: Mirrors,detectors, and wavefront control
Key technology challenges forNGST include lightweight optics,cryogenic actuators for mirror control,deployable structures, sensitiveinfrared detector arrays, lightweight,programmable aperture masks formulti-object spectroscopy, and coolersfor the thermal infrared detectors. Allhave seen significant progress over thelast two years.
MirrorsThe NGST primary mirror must be
lightweight (~20 kg/m2) anddeployable and must be capable ofholding its figure at cryogenictemperatures. So far, eight designsinvolving five industry partners —including the University of Arizona,Composite Optics Inc, Ball Aerospace,Raytheon Optical Systems, and Kodak— have been built as prototypeultralight mirrors. The University ofArizona built a 2m “bed of nails”mirror which uses a 2mm facesheet ofglass over a bed of more than 160actuators to control the deformablesurface. COl and IABG (Germany)developed a carbon-fiber, reinforcedsilicon-carbide, semi-rigid mirror thatuses sparse actuation to control radiusof curvature and tip, tilt, and piston ofthe mirror. Ball Aerospace built aberyllium mirror (see figure aboveright), which has recently undergonecryogenic testing at Marshall SpaceFlight Center to quantify the changesin figure due to temperature. Theresults are extremely encouraging forthe concept of “cryofiguring” whereinterferograms taken at cryo-tempera-tures are used to control the last stagesof polishing.
The next stage of mirror develop-ment will include fabrication andtesting of larger demonstration mirrors.Three different technologies wereselected for phase II of the AdvancedMirror System Demonstrator (AMSD).
Over the next two years, the threecontractors will fabricate, assemble,and test full-size mirror segments, i.e.Rayheon’s “Glass Meniscus”, Kodak’s“Fused Silica”, and Ball’s “Light-weight Beryllium” mirrors. They mustdemonstrate manufacturing and testingtechniques and show that their mirrorswill be capable of adjustment once inorbit and be able to work in tempera-tures that vary from 300 K to 40 K.
DetectorsNGST requires detectors with large
formats, a low dark current, andminimal readout noise. Candidates forthe 0.6 to 5 micron region includeindium antimonide (InSb) andmercury-cadmium telluride (HgCdTe)technologies, while arsenic-dopedsilicon (Si:As) holds the most promisefor the longer wavelengths. Thetechnical requirements that thesedetectors aim to meet are spelled out inthe report of the NGST DetectorRequirements Panel and summarizedon the NGST web page (http://www.ngst.nasa.gov/cgi-bin/doc?Id=538and http://www.ngst.nasa.gov/cgi-bin/doc?Id=641). For the near-IR (0.6 to 5microns), both HgCdTe (U. Hawaii/Rockwell Science Center) and InSb(U. Rochester/Raytheon) are beingsupported as candidate options.
NGST from page 6
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The ISWG Membership includes:
Heidi HammelSpace Science Institute
George HelouCalTech/SIRTF Science Center
Robert KennicuttUniversity of Arizona
Robert KirshnerHarvard University
Rolf-Peter KudritzkiIfA University of Hawaii
Simon LillyUniversity of Toronto
Bruce MargonSpace Telescope Science Institute
Mark McCaughreanAstrophyics Institute Potsdam
Marcia Rieke (Chair)University of Arizona
Massimo StiavelliSpace Telescope Science Institute
Edwin TurnerPrinceton University
Ewine van DishoeckLeiden University
Michael WernerJet Propulsion Laboratory
Newsletter • Space Telescope Science Institute
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Through these contracts, multi-chipfocal-plane modules will be developed,chip manufacturing will be improved,readout sensitivity will be enhanced,and potential cost drivers and costsavings will be identified. Work alsocontinues at Raytheon and Ames onthe mid-IR candidate material, Si:As.Bare readouts of the new SB-226detector have been evaluated down to5 K, and optimum lot splits will beidentified soon. Prototype 1k × 1kSi:As hybrid arrays (27 micron pixels)have been fabricated, with excellent
operability. Detailed low-backgroundcharacterization is continuing.
Wavefront Control TestbedThe Wavefront Sensing and Control
Testbed (WCT) is a joint projectbetween GSFC and JPL for NGST. Itspurposes are to simulate the co-phasing process for NGST, deepen ourunderstanding of all aspects of thisprocess, develop and improve thealgorithms for sensing and control ofeach step, and characterize the effectsof various parameters on accuracy,sensitivity, repeatability, and reliability.
NGST Town Hall at 198th AAS Meeting in Pasadena
Thursday, 7 June 2001, 1:00-2:00pm
The NGST (Next Generation Space Telescope) Project is entering an exciting new phase, one which offers
important opportunities to members of the astronomical community. Having analyzed the performance, cost,
and development schedule for the observatory, NASA has initiated the process of selecting the aerospace
contractor that will be responsible for the final design and construction of the NGST. Beginning this year, NASA,
along with its NGST partner agencies, ESA and the Canadian Space Agency (CSA), will select the scientists that will
define and execute the first scientific observations with NGST and will lead and oversee the development of the
observatory and its scientific instruments.
This Town Hall will begin with summaries of the project status and the viewpoint of the Interim Science Working
Group (Marcia Rieke, chair). Senior members of the Project science team will outline the opportunities for leading the
development of the Near Infrared Camera and the Mid-Infrared Camera/Spectrograph (a joint ESA/US venture).
NASA plans to release an Announcement of Opportunity for these roles, observatory-level scientists, and interdiscipli-
nary scientists on the flight Science Working Group shortly after the summer AAS meeting. We urge those interested
in NGST to attend this meeting and will allocate much of the meeting for addressing questions. Before the meeting,
please visit the website www.ngst.nasa.gov. To subscribe to announcements and procurement news about NGST, see the
link from the NGST home page or go to http://www.ngst.nasa.gov/News/lists/index.html.
Organized by H.S. (Peter) Stockman NGST Study Scientist: [email protected]
WCT1 incorporates a pair of deform-able mirrors for injection of controlledaberration and correction. WCT2incorporates a small, three-segmentrigid mirror assembly with tip/tilt andpiston correction. The experiment suitefor WCTI is nearly complete(see figure below), and the WCT2assembly has recently been commis-sioned with the demonstration of theinitial co-phasing.
This paper is largely based on anNGST flier which was distributed atthe last AAS Meeting in San Diego.
NGST from page 7
March 2001
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The Cycle 10 Review ProcessGeorges Meylan, [email protected] and Meg Urry, [email protected]
The HST Cycle 10 panels andTAC (Telescope AllocationCommittee) met at STScI
between November 10 and 19, 2000.The proposal review process was thesame as that used a year earlier forCycle 9, with only minor changes.With the review now fully completed,we have received extensive feedbackfrom the panel and TAC members, aswell as from the astronomicalcommunity, generally indicating strongapproval for the present system andmaking some useful suggestions forfuture improvements. We brieflydescribe the organisation of the reviewprocess and provide some practicaladvice for proposers in futureHST cycles.
Towards Science BalanceBefore Cycle 9, the balance among
scientific sub-disciplines was estab-lished by proposal pressure in a sub-discipline, modified slightly bysubsequent TAC discussions. Valuejudgments about the relative impor-tance of any one sub-discipline versusany other were therefore made by avery large committee (of about 25people in the TAC) representing allfields of astronomy but with little timefor in-depth discussions. In Cycles 9and 10, science balance was insteaddetermined by in-depth discussions ofexperts in panels that were broaderthan the old 17-topic panels, but morefocussed, and with far more specificexpertise in the areas discussed, thanthe full TAC. The panels allocated allthe orbits available for regularprograms; the TAC allocated all theorbits available for large programs.The present panels are broad enough tocover several topics but narrow enoughto have the requisite scientificexpertise with the science in each ofthese topics.
Conflicts of InterestA major goal of the new process is a
substantial decrease in the number ofconflicts of interest. The proposals
were assigned, according to theirscientific categories, to one of ninepanels covering five general scienceareas. To minimise conflicts while stillallowing experienced HST users toparticipate in the review process, weassigned two twin panels to each offour science areas, then added theSolar System panel, for which therewere too few proposals to split.
As a consequence, the acceptancerate was the same for PIs who servedas reviewers and those outside theprocess. There were also dramaticallyfewer instances of panelists havingto recuse themselves because ofconflicts of interest, leading to theconstant presence of a larger fractionof panel expertise.
More ExpertsTo improve on Cycle 9, we added
one more expert in each panel in orderto ensure the presence of one expertfor each of the scientific categoriescovered. We were also careful to haveone or more theorists per panel. Thepanel members were chosen to coverthe entire mix of science represented
by the submitted proposals. A total of81 experts participated in the Cycle10 review.
In spite of the fact that twin panelshad very similar scientific expertise,they came up, in a few cases, withsome different mixes of science.This is expected in peer review whichrecognises there is no absolute“correct” way to choose proposals.
Large and Regular ProgramsTwenty-one large programs,
requesting 100 orbits or more, werereviewed by the TAC only. They werediscussed first before and then after thepanel meetings, in order to be able totake into account comments from theexpert panelists. Up to 1000 orbitswere made available to these largeprograms and 589 were awarded, toseven programs (cuts were to eliminateduplications). Among the regularprograms, requesting 99 orbits orfewer, the medium-size programs,requesting between 15-99 orbits, werefavored via orbit subsidies in thereview process. To encourage moresubmissions of large and medium-sizeprograms, these review processes were
% o
f Pro
posa
ls w
ith a
Con
flict
Cycle
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
43%
7 AR
58%
7
48%
8
22%
9
23%
10
52%
7 NIC
continued page 10
Newsletter • Space Telescope Science Institute
10
heavily advertised in the Call forProposals, the STScI Newsletter, andon the web.
Once again, the oversubscriptionrate was very high: about one proposalin five was allocated time. Theacceptance rate was essentiallyindependent of the proposal size, i.e.,of number of orbits requested. Largeprograms were allocated eventuallyabout 20 % of the total number oforbits available, as recommended byexternal advisory committees.
Advice for Future CyclesThe present HST review process
having achieved most of our goals, weplan to again use this basic structure infuture cycles. This means futureproposers should keep in mind severalkey points:
• Do not hesitate to submit Largeproposals, if scientifically justified,
Cycle 10 Review from page 9
since they have the same chance ofsuccess as any other proposal (possiblyeven better, since in Cycle 10 one 1in three Large proposals was grantedtime). The TAC discusses each Largeproposal in considerable details so thewinning proposals are not only ofcompelling scientific interest, theyare well thought out and involveexpert teams.
• Make the effort to address the non-expert present “the big picture”.The most successful proposals set thecontext with sufficient backgroundinformation and convincingly describethe importance of the investigation toall astronomy. Since this was anexplicit criterion for evaluation,proposals could be downgraded forfailing to address this point.
• Do not pad your request for time.Fewer than 5 % of the approvedproposals were cut (and those only to
avoid duplicate observations):proposers either got the time theyasked for or were rejected.
• Start from the science, write acompelling story for your fellowastronomers. Ask for the resourcesgenuinely needed, and submitproposals, whatever their size.
We expect the number of proposalsto increase for the next cycle becauseof the availability of two moreinstruments: NICMOS and ACS. Thepast high oversubscription rate (1/5)may therefore be even higher. Manytruly excellent proposals have to berejected, but remember that rejectedPIs are in very good company and thatmany of these proposals, possiblyrevised according to comments fromthe panel or TAC, may succeed infuture cycles...
HST Recent Release:Astro-Entomology? Ant-like SpaceStructure Previews Death of Our Sun
From ground-based telescopes, thiscosmic object -- the glowing remainsof a dying, Sun-like star -- resemblesthe head and thorax of a garden-variety ant. But this dramatic Hubbletelescope image of the so-called "antnebula" (Menzel 3, or Mz3) showseven more detail, revealing the "ant's"body as a pair of fiery lobes protrudingfrom the dying star.
Image Credit: NASA, ESA and TheHubble Heritage Team (STScI/AURA)
Web Address: http://oposite.stsci.edu/pubinfo/pr/2001/05/
March 2001
11
CYCLE
10Solar SystemFran Bagenal, Chair, University of ColoradoJim Bell, Cornell UniversityBill Hubbard, University of ArizonaJohn Davies, Joint Astronomy Center, HawaiiBill McKinnon, Washington UniversityJames Friedson, Jet Propulsion LaboratoryYuk Yung, California Institute of TechnologyTimothy Dowling, University of LouisvilleMike Belton, Nat’l Optical Astronomy Observatory, Tucson
Galactic 1Regina Schulte-Ladbeck, Chair, University of PittsburghRobert Blum, CTIO, ChileDave Arnett, Steward Observatory, University of ArizonaPatrick Harrington, University of MarylandMichael Jura, University of California at Los AngelesSusan Trammell, University of North Carolina at CharlotteCarole Haswell, Open University, Milton Keynes (UK)Wesley Traub, Harvard-Smithsonian Center for AstrophysicsKent Honeycutt, Indiana University
Galactic 2Harry Shipman, Chair, University of DelawareMatthew Bobrowsky, Challenger Ctr. for Space Sci. Edu.Lex Kaper, Free University AmsterdamJohn Dickel, University of Illinois at Urbana-ChampaignDimitar Sasselov, Harvard UniversityRichard Rothschild, University of California at San DiegoSilvia Torres-Peimbert, Universidad Autónoma de MéxicoPhilip Massey, Lowell ObservatoryAlbert Zijlstra, European Southern Observatory (Germany)
Galactic 3Marcia Rieke, Chair, Steward ObservatoryNeill Reid, University of PennsylvaniaFrancesco Ferraro, Osservatorio Astronomico di BolognaTom Ayres, CASA, University of ColoradoNeal Evans, University of Texas, McDonald ObservatoryMarcio Catelan, University of VirginiaBernie McNamara, New Mexico State UniversityRobert Mathieu, University of WisconsinJochen Eisloeffel, Thueringer Landessternwarte Tautenburg
Galactic 4Alvio Renzini, Chair, ESO, Germany & University of BolognaShoko Sakai, University of California at Los AngelesRodrigo Ibata, Max-Plank-Institut fuer AstronomieMichael Sitko, University of CincinnatiDennis Zaritsky, Steward ObservatoryNancy Evans, Smithsonian Astrophysical ObservatoryJeffrey Linsky, JILA, University of ColoradoJennifer Wiseman, Johns Hopkins UniversityLee Hartmann, Harvard-Smithsonian Center for Astrophysics
Extragalactic 1Michael Rowan-Robinson, Chair, Imperial College, LondonMitchell Begelman, University of ColoradoChris Pritchet, University of VictoriaHermann-Josef Roeser, Max-Plank-Institut fuer AstronomieJeff Kenney, Yale UniversityCarole Mundell, John Moores University, LiverpoolKaren Leighly, University of OklahomaEric Emsellem, University of LyonRoelof de Jong, University of Arizona
Extragalactic 2Matthew Malkan, University of California at Los AngelesRoger Davies, University of DurhamZlatan Tsvetanov, Johns Hopkins UniversityTom Statler, Ohio UniversityJean Brodie, University of California at Santa CruzThrinh Thuan, University of VirginiaLuis Colina, Instituto de Física de CantabriaMike Eracleous, Pennsylvania State UniversityElena Pian, ITESRE-CNR, Bologna
Extragalactic 3Hyron Spinrad, Chair, University of California at BerkeleyJill Bechtold, University of ArizonaChris Kochanek, Harvard-Smithsonian Ctr for AstrophysicsErica Ellingson, University of ColoradoKen Lanzetta, State University of New York at Stony BrookChristian Vanderriest, Observatoire de Paris, MeudonJulio Navarro, University of VictoriaPeter Garnavich, University of Notre DamePieter van Dokkum, California Institute of Technology
Extragalactic 4Wal Sargent, Chair, California Institute of TechnologyChristine Jones, Harvard-Smithsonian Ctr for AstrophysicsJohn Tonry, University of HawaiiSteve Warren, Imperial College, LondonSteven Myers, National Radio Astronomy ObservatoryTheresa Brainerd, Boston UniversityRafael Guzman, Yale UniversityLaura Ferrarese, Rutgers UniversityDaniel Eisenstein, University of Chicago
Scott Tremaine, TAC Chair, Princeton University
Panels
Newsletter • Space Telescope Science Institute
12
CYCLE
10
State Submitted ApprovedAL -------- 10 0AZ -------- 61 17CA -------- 125 28CO -------- 26 5CT -------- 10 2DC -------- 12 1DE -------- 2 0FL --------- 1 0GA -------- 4 0HI --------- 20 4IL ---------- 20 2IN --------- 10 3KY -------- 2 0LA -------- 2 0MA -------- 41 10MD ------- 155 50MI --------- 19 5MN ------- 6 1NC -------- 4 0NE -------- 1 0NH -------- 1 0NJ -------- 12 3NM ------- 8 3NV -------- 3 0NY -------- 33 9OH -------- 12 1OK -------- 4 1OR -------- 3 1PA -------- 36 6RI --------- 1 0SC -------- 3 0TN -------- 5 1TX --------- 15 2VA -------- 10 1WA -------- 12 3WI --------- 17 2
STScI ---- 78 28
Country Submitted ApprovedAustralia 14 4Austria 2 0Belgium 1 0Canada 18 3Chile 2 0France 26 5Finland 5 0Germany 31 4India 3 0Ireland 4 0Israel 2 0Italy 17 1Korea 1 0Mexico 1 1Poland 1 0Spain 9 1Sweden 7 0Switzerland 1 0Netherlands 4 3United Kingdom 51 9United States 706 160Venezuela 1 0
ESA Proposals 164 26
Proposals by Country:
US PIs by State:
Panel and TAC Orbit Trimming by Cycle
Cycle 6: 174 out of 435 Approved GO programs were trimmed (40%)Cycle 7: 82 out of 241 Approved GO programs were trimmed (34%)Cycle 8: 58 out of 231 Approved GO programs were trimmed (25%)Cycle 9: only 13 out of 145 Approved GO programs were trimmed! (9%)Cycle 10: only 10 out of 136 Approved GO programs were trimmed! (7.4%),and these were mostly duplication issues.
Median Orbits Median OrbitsSubmitted Approved
Cycle 6 12 8
Cycle 7 14 9
Cycle 7N 12 12
Cycle 8 12 10
Cycle 9 15 13.5
Cycle 10 15 13
Oversubscription by Cycle
Ove
rsub
scrip
tion
Rat
io
Cycle
GO Orbit oversubscriptionGO Proposal oversubscriptionAR Funding oversubscription
1 2 3 4 5 6 7 7N 8 9 100.00
2.00
4.00
6.00
8.00
10.00
OrbitsProposals
Cycle 10 Acceptance Fraction by Proposal Size
Orbit Bin
1-10 11-20 21-30 31-40 41-50 51-99 Large Overall0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
5733 19
6
7
7
7
March 2001
13
CYCLE
10
Cycle 10 Proposal Results by Panel
Summary of Cycle 10 Results
* Doesn’t include 398 Parallel orbits.
Approved % Total Orbits % Total
Proposals by Instrument*
FGS 11 6.1% 144 4.7%
STIS / CCD 54 30% 837 + (398) 27.2%**
STIS / MAMA 59 33% 972 31.6%
WFPC2 56 31% 1120 36.4%
* Includes coordinated parallel as well as multi-instrument proposals.** Excludes 398 Pure Parallel orbits.
Cycle 10 Orbit Results by Panel
Gal1 Gal2 Gal3 Gal4 Exgal1 Exgal2 Exgal3 Exgal4 SS TAC TOTAL
Submitted
1490 1608 1747 1608 2036 1395 1733 1610 379 2630 16236
Approved
269 325 259 257 341 268 241 256 113 589* 2918
Panel Fraction of Total Approved
9.20% 11.10% 8.90% 8.80% 11.70% 9.20% 8.30% 8.80% 3.90% 20.20% –
Fraction of Orbits Approved/Submitted
18.10% 20.20% 14.80% 16% 16.70% 19.20% 13.90% 15.90% 29.80% 22.40% 18%
Gal1 Gal2 Gal3 Gal4 Exgal1 Exgal2 Exgal3 Exgal4 SS TAC TOTAL
Proposals Submitted
GO 107 104 95 88 86 80 62 60 33 21 736
SNAP 11 13 8 7 13 15 7 4 6 – 84
AR 5 7 4 13 9 11 12 17 9 – 87
Total 123 124 107 108 108 106 81 81 48 21 907
Proposals Approved
GO 23 17 17 18 12 14 9 10 9 7 136
SNAP 4 2 1 0 5 2 3 1 1 – 19
AR 1 5 1 7 3 5 4 7 4 – 37
Total 28 24 19 25 20 21 16 18 14 7 192
Requested Approved % Accepted ESA Accepted ESA % Total
Proposals
GO 736 136 18.5% 24 17.5%
SNAP 84 19 22.6% 2 10.5%
AR 87 37 42.5% — —
Total 907 192 21.2% 26 13.5%
Primary Orbits 16,236 2,918* 18 442 15.8%
Newsletter • Space Telescope Science Institute
14
Galac
tic P
rogr
ams
Bahc
all
GO
Inst
itute
for A
dvan
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March 2001
15
Hea
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Approved Observing Programs for Cycle 10
Newsletter • Space Telescope Science Institute
18
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Approved Observing Programs for Cycle 10
March 2001
19
PyRAF: a Python-based command language for IRAFPerry Greenfield and Richard L. White, [email protected]
Both STScI programmers andHST users would benefit fromtools that would make it easier
to develop more powerful, flexible,and user-friendly data analysissoftware. We believe, however, thatany effort to enhance or replace oursoftware environment cannot succeedunless we retain the ability to use thegreat variety of useful tasks thatalready exist in IRAF, STSDAS,and TABLES.
The cornerstone of the ScienceSoftware Group’s plans for the futureis our project to develop a newcommand language for the IRAFenvironment. We’ve based the newcommand language on Python, a free,portable, object-oriented scriptinglanguage. The new command lan-guage, PyRAF, is itself written almostentirely in Python, and PyRAF scriptsare Python scripts. The new commandlanguage provides a number ofadvantages: it has an improvedinteractive environment, much morepowerful scripting capabilities, and theability to integrate 3rd party non-IRAF-based software and libraries farmore easily. Eventually, we intend toadd IDL-like array manipulation,plotting, and image display capabili-ties. It is our hope that ultimately we(and many of our users) will writemost applications in PyRAF ratherthan C, Fortran, or SPP.
We chose Python over other, better-known scripting languages primarilybecause it is easier to learn and read,has better support for interactive use,and is better suited to writing largeapplications. Even though it is not themost widely used language, Python iswell established and has a sizable userbase that is growing rapidly. Python isheavily used by many businesses,including Hewlett-Packard, LawrenceLivermore National Laboratory,Google, and Industrial Light andMagic. By basing our commandlanguage on a well-supported scriptinglanguage, we benefit enormously fromits large developer community and the
extensive libraries available for it.While for our users this does meanlearning another language, it is alanguage that has general use wellbeyond astronomical data reduction.Python can be used in place of shellscripts, awk, Perl, and similar tools.
The PyRAF interactive environmentis intentionally very similar to theexisting IRAF CL. In fact, with veryfew exceptions, IRAF tasks can beinvoked from the command line withexactly the same syntax as is used inIRAF CL. (Only PyRAF scripts mustuse Python syntax.) Nearly all IRAFtasks and scripts can be run, includingthose that use IRAF-compatible imagedisplay programs. PyRAF fullysupports IRAF interactive graphicstasks. All IRAF hardcopy graphicsdevices are available.
PyRAF’s enhanced interactiveenvironment includes a number ofconveniences not available in thestandard IRAF CL:
• Command line recall using thearrow keys
• Command and filename completionusing the tab key
• A GUI-based parameter editor
• A GUI help window availablesimultaneously with the parametereditor
• Multiple graphics windows and theability to recall previous plots
• Improved window focus handling
As a scripting environment,PyRAF has a number of significantadvantages:
Error handling
• IRAF CL scripts die if any task failsand do not indicate where it stopped.On the other hand, Python hasexcellent exception handling.Untrapped errors result in a messageindicating on which line in the scriptthe error occurred, and exceptions
can be caught and handled withinthe scripts. PyRAF can even be usedto debug IRAF CL scripts!
A scripting language that provides:
• Ease of learning andcomprehension.
• Convenient and useful datastructures such as lists anddictionaries.
• Rich string manipulation andpattern-matching facilities (includ-ing Unicode).
• Well designed object-orientedcapabilities (while still allowingsimple procedural scripts orprograms.)
• Extensive documentation andsupport. In addition to the gooddocumentation provided withPython, many books on Python havebeen published (more than 20 at lastcount with more on the way). Thedeveloper community provides awealth of information and helpthrough usenet news groups andmailing lists. Commercial support isavailable.
Numerous libraries including:
• Graphical User Interface tools.
• OS access (file and directorymanipulation, systemenvironment, etc.).
• Internet and networking tools(HTML & XML parsing, mailhandling, ftp and telnet, etc.)
• Profiling and debugging modules.
Ability to link in existing C, C++, orFortran code.
PyRAF provides an excellent meansof integrating non-IRAF software(astronomical or otherwise) withIRAF tasks.
PyRAF has been available internallyat STScI and at a few test sites sincespring 2000. The Science SoftwareGroup released a generally available
continued page 20
Newsletter • Space Telescope Science Institute
20
Project Scientist’s ReportD. Leckrone, GSFC, [email protected]
veterinary surgeon and his previoustwo shuttle flights have focussed onLife Sciences experiments. It is saidthat, when Richard was first contactedabout his selection for the next Hubblerepair mission, he was in SoutheastAsia attaching prosthetic limbs toelephants whose legs had been blownoff by land mines! Clearly he brings alot of experience to our mission inapplying fine manual dexterity tolarge, bulky objects - perfect for HSTservicing!! Although STS-109 will beMike Massimino’s first shuttle flight,he has proven to be one of the mostaccomplished EVA trainees in arigorous testing program organized byJohn Grunsfeld. Mike holds a Ph.D. inMechanical Engineering.
SM3B will initiate an exciting timefor astronomy. The new AdvancedCamera for Surveys (ACS) will finallyget its chance to show us its mettlewith over twice the field of view ofWFPC2, sampled with PC-like angularresolution, and with substantiallygreater throughput. And with theexperimental new technology of theNICMOS cryocooler, we havereasonable prospects for revivingHubble’s near-infrared capabilities.After replacing the current solar arrayswith smaller, more efficient rigidarrays, we will be leaving Hubble withplently of electrical power for theremainder of the mission (as well as a“new look”). And the changeout of theaforementioned Power Control Unit
will assure that we can take fulladvantage of all those watts withoutfear of a major electical system failurein the future.
Now that our EVA crew has beennamed, we are able to establish alaunch-readiness date of October 15,2001 for the SM3B mission. However,there remain some uncertainties aboutthe availablity of Space ShuttleColumbia in this time frame. CurrentlyColumbia is undergoing a majoroverhaul in Palmdale, CA. Thisincludes extensive repairs of wiringproblems, similar to those carried outrecently on all the other orbiters in thefleet. The longer than expected repairprocess could force a further delay inSM3B to February or March of 2002.However, our colleagues at NASAHeadquarters are currently trying tonegotiate a “swap” of launch dateswith another mission that is now aheadof us in the queue for flight onColumbia so as to prevent such adelay. Launch delays are especiallybad news for the HST (and Office ofSpace Sciences) budget. Previouslaunch slips have cost the HSTprogram many millions of dollars,drawn from our contingency funds.Any future slips would threaten ourability to pay for future instruments,WFC3 and COS. Needless to say, wewish Code S all the best in attemptingto stem this serious drain on theresources available for HST.
Servicing Mission 3B
On September 28, NASAformally announced theselection of the four
astronauts who will conduct the fiveEVAs currently planned for the nextHST servicing mission, STS-109. Thisis a very strong group, well up to thechallenges posed by Servicing Mission3B. The crew is led by Hubbleservicing veteran (and high-energyastrophysicist) John Grunsfeld. Johnhas flown on three previous shuttleflights. In December 1999, heperformed two spacewalks to serviceHubble during servicing mission 3A(STS-103). In practice runs in theNeutral Buoyancy Laboratory atJohnson Space Center in Houston,John has developed the techniques forchanging out Hubble’s Power ControlUnit (PCU). His work has given ushigh confidence that this challengingmaintenance task can be carried outsafely and successfully in less than oneEVA. We’re feeling a lot betterabout it!
Joining John Grunsfeld are twoother veteran astronauts, Jim Newmanand Richard Linnehan, and one rookie,Mike Massimino.Newman, whosePh.D. is in Physics, has flown on threeshuttle missions since 1993. In 1998 heperformed three spacewalks on thefirst International Spacestationassembly mission. Interestingly,Linnehan’s background is as a
beta version in January 2001. We arestill improving the installation process;the current beta version is easilyinstalled on Solaris or Linux systemsbut requires more effort on othersystems. We will eventually support allplatforms on which STSDAS issupported. (Note that Python itself also
runs on platforms not supported byIRAF, such as Windows and MacOS.)While we will continue to enhance theIRAF features of PyRAF, we have alsostarted work on the IDL-like capabili-ties. This includes a full-functionedFITS I/O module, improved arraymanipulation facilities, and plotting
and display tools. Finally, we havebegun developing our own scripts andapplications in PyRAF, including anew drizzle script that will be muchmore powerful and flexible than thecurrent CL script. More informationabout PyRAF is available athttp://pyraf.stsci.edu.
PyRAF from page 19
March 2001
21
INST
RUM
ENT
NEW
S
Advanced Camera for Surveys (ACS)Mark Clampin, [email protected]
The Advanced Camera for Surveys (ACS) is thenext generation of imaging instrumentation forthe Hubble Space Telescope (HST). ACS has
three imaging channels optimized for wide field, near-UV and far-UV imaging. The Wide Field Channel(WFC) will offer a ~200 × 200 arcsec field of view withpeak throughput of ~40%, including the OTA. The near-UV channel is optimized for imaging in the near-UVand features fully sampled imaging in the visible (0.025arcsec/pixel). The Solar Blind Channel (SBC) isoptimized for far-UV imaging and low dispersionspectroscopy (R~100).
ACS has completed integration of its flight detectorsand has recently completed the process of imagealignment checking. It has also started with its groundcalibrations. During these tests, internal and externalflat fields will be obtained for all detector and filtercombinations so that a pre-launch calibration of ACScan be developed in the coming months. The instrumentwill now be delivered to the Goddard Space FlightCenter where it will start a series of final tests, includ-ing a thermal-vacuum test. Due to a re-evaluation of theServicing Mission 3B schedule, it has been necessary todrop the installation of the Aft-Shroud Cooling System(ASCS) until Servicing Mission 4 (SM4). Consequently,ACS will run for the first two years using only passivecooling within the aft-shroud of HST. Thermal modelingsuggests that this would not be a problem for ACS untilafter SM4, when the Cosmic Origins Spectrograph(COS) is installed. The CCD detectors will initially onlyrun a degree or two warmer resulting in little change inthe dark current rates for the first few years of scienceoperations. The thermal-vacuum test will validate theinstrument’s performance in this new thermal environ-ment. Following SM4, ACS will operate with theexternal radiator installed as part of the ASCS.
The ACS will be offered to GOs for the first timein Cycle 11. Current details on the instrument’sexpected performance are summarized in the ACSInstrument Handbook, with late-breaking news on theACS web pages.
Near-Infrared Camera and Multi-Object Spectrometer (NICMOS)Daniela Calzetti, Torsten Boeker, Larry Petro& Eddie Bergeron, [email protected]
NICMOS, the Near-Infrared Camera and Multi-Object Spectrometer, is a cryogenic instrumentand provides the only infrared capability
currently on board HST. NICMOS operated successfullyfrom February, 1997 to January, 1999 (Cycles 7 and7N), using solid N
2 ice as a coolant. NICMOS has been
inactive since January 3, 1999, after depletion of the N2.
The instrument will be re-activated with an activecooling system (the NICMOS Cooling System) duringservicing mission SM3B, currently scheduled for theend of 2001.
NICMOS offers imaging, spectroscopic, polarimetric,and coronographic capabilities at infrared wavelengths(0.8 to 2.4 microns) in three cameras, NIC1, NIC2, andNIC3. The three cameras have different magnificationfactors, with Field of Views of 11 × 11 arcsec, 19.4 ×19.4 arcsec, and 51.2 × 51.2 arcsec, and pixel sizes of0.043, 0.076, and 0.20 arcsec, respectively. Two of thethree cameras, NIC1 and NIC2, are nearly parfocal, andcan be used for simultaneous observations; their Fieldsof View are about 33 arcsec apart. NIC3 has a separatefocus, and when operations are resumed, its optimalfocus is expected to be slightly out of the range of thePupil Alignment Mechanism, the mechanism thatcontrols the focus of the instrument. This is a conse-quence of a plastic deformation of the NICMOS dewarwhich also caused a thermal short soon after installationon the telescope and led to the reduced lifetime of thecryogen. However, the NIC3 best achievable focus iswell suited for science observations, showing less than10 to 15% loss in the encircled energy in a 0.2 arcsec(1 pixel) radius, as compared to the optimum focus.
During its first operational period, the three NICMOSdetectors operated at a temperature around 60 K, with aslow upward trend from 59.5 K to ~62 K, as the N
2
sublimated. After the installation of the NCS, NICMOSis expected to operate at a higher detector temperature,the exact value of which is still uncertain. Thattemperature depends critically on many factors: theactual NCS on-orbit performance, the parasitic heat loadon the NICMOS dewar and on the NCS, the tempera-ture attained by the heat-rejecting external radiators, andthe thermal gradient within the NICMOS cryostat.Current estimates suggest it will be somewhere in therange ~75 to 86 K with a best estimate of 78.5 K.Because of this range for the operating temperature,
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predictions of the instrument performance are alsosomewhat uncertain.
The detector dark current increases with temperature.When solid nitrogen was in NICMOS, typical valueswere <0.05 e-/s.Predictions for the dark current underNCS operations depend not only on the actual detectortemperature but also on whether a dark current excessobserved during the instrument warm-up is present ornot (see the June 1999 STScI Newsletter and Figure 1).
During the last days of operation, in January 1999,while the instrument was warming up after the cryogendepletion, the dark current showed a transient enhance-ment (see top panel of figure below) that exceeded theexpected exponential profile in the temperature range ofabout 75 to 86 K. This excess reached its peak around82 K, with a dark current that was about one order ofmagnitude higher than the expected trend (compare topand bottom panels of the figure). A ‘valley’ in darkcurrent values was also observed between ~86 K and~90K, which marks the transition to the standardexponential profile. Since the nature of the dark currentexcess remains unexplained, we cannot predict whetherit will be present during future NICMOS operations,
and we have to await on-orbit testing. After the NCS isinstalled on HST and its performance established, wewill attempt to operate NICMOS at the minimum stabledetector temperature for which the dark current is~2 e-/s or less. While this is higher than during theprevious NICMOS life, it is still low enough to notsignificantly impair NICMOS’ science capabilities.The temperature range for which the dark currentremains below this threshold is highlighted in magentain the figure, both with (top) and without (bottom) thedark current excess.
The DQE of the NICMOS detectors operating at ~75-86 K is expected to be higher than that at ~60-62 K,with a typical increase of ~40-65% at 1.1 micron, ~30-50% at 1.6 micron, and 20-25% at 2.2 micron. In termsof sensitivity, the higher DQE partially compensates forthe increased dark current. The decrease in overallperformance relative to Cycles 7 and 7N is expected tobe small, with a worst-case loss in limiting magnitudeof ~0.3 mag for long exposures below ~1.7 micron.
We are therefore looking forward to a renewedNICMOS and another scientifically productive periodof near-infrared observations with HST.
WFPC2John Biretta, [email protected]
WFPC2 remains HST’s workhorse imaginginstrument, at least for the time being. Itcontinues to perform well and averages
about one thousand images per month. Its seven years inthe harsh space environment are, however, slowlytaking their toll. This is evidenced by the slowlyincreasing CTE problem in the CCD detectors and bythe recent anomaly in the shutter operation. Here wediscuss these issues. We also report on the updatedWFPC2 Instrument Handbook.
Degradation of the Charge Transfer Efficiency (CTE)in the WFPC2 is an increasing concern for observers,and considerable efforts are being made to study itseffects. The most notable effects are on point-sourcephotometry where the ongoing radiation damage causean ever increasing fraction of counts to be lost duringthe readout process. For example, at the current epochwe expect that a faint (100 electrons total) point sourceat the center of one of the Wide Field CCDs will loseapproximately 19% of its counts during readout in atypical broadband exposure (e.g., 300s, F555W filter, as
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measured in a typical 2-pixel-radius aperture). Thesignal-to-noise ratio for such an image is four, so this19% loss begins to become significant. If one is dealingwith photometric averages across many targets, the 19%systematic loss could, of course, be quite important.Larger effects will be seen for very short exposures, ornarrow-band and UV filters where there is less skybackground, or for targets farther from the readoutamplifier. For example, a similar image exposed for300s in F656N but near pixel (X,Y) = (800,800) willlose about 60% percent of its counts to CTE. This willhave a severe impact on the photometry, as well as onthe detectability of this target. (More specific simula-tions can be performed using the CTE estimator tool atour web site.)
For small targets, the best way to minimize CTE is toplace the target near the CCD readout amplifier, as thisminimizes the number of charge transfers. For the WideField Camera (WFC), this can be achieved by placingthe target at the WFALL aperture, which is near pixel(133,149) on the WF3 CCD. For the Planetary Camera,this can be achieved by using POS TARG -12.3,-12.5with PC1-FIX which will place the target on PC1 CCDnear pixel (150,150). We note that in general, the WFCCCDs will have higher background counts, and hencelower CTE, than the PC1 CCD, and hence can beexpected to give somewhat better photometric perfor-mance on faint targets.
Another method of reducing CTE is to pre-flash theCCDs so as to increase the background counts in thescience image. This could, in principle, be achievedusing various internal lamps inside WFPC2. However,for the vast majority of science programs, the addedphoton noise and overheads contributed by the preflashwill make this unattractive. Preflashing may be useful insituations where photometric accuracy and uniformity isof paramount importance and detection of faint targetsis not an issue. We have also performed tests of a noise-less preflash technique where the CCDs are preflashedand cleared before the science exposure, but thisappears to give only a modest reduction in CTE.Apparently most of the electron traps responsible forCTE in the CCDs are short lived (milliseconds) and arenot quenched by a preflash occurring one minute beforethe science exposure (Schultz, Heyer, and Biretta,WFPC2 ISR 01-02).
For many observers, the most promising technique isto apply photometric corrections during data analysis.Whitmore, Heyer, and Casertano published a series of
corrections in December, 1999 (PASP 111, 1559). Morerecently Dolphin et al. (PASP 112, 1397) have publishedan independent set of corrections. In general, theirresults are in good agreement with those of Whitmore,et al. and are consistent within a few hundredths of amagnitude. At the faintest levels, the correctionsdiverge, and we believe the Whitmore corrections areprobably more accurate due to having many more faintstars in the sample. For the time being, it appears thebest results would be obtained by using the Dolphincorrections above 100 target electrons (their model hasless scatter) and the Whitmore, et al. corrections atfainter levels. A more detailed comparison of thesecorrections is underway and will be reported on theWFPC2 web page soon.
Besides these photometric effects, CTE also appearsto cause modest distortions in the shapes of images.Reiss (WFPC ISR 00-04) has studied the effect of CTEon the profiles of faint galaxies by comparing imagestaken near and far from the readout amplifier. The maineffect is for charge to be preferentially lost from the sideof the target nearest the readout amplifier. The side ofthe target farthest from the readout amplifier appears tosuffer little or no loss of charge. This, of course, willtend to cause artificial asymmetries in the shapes oftargets. Work is underway to develop a model whichcan predict, and possibly correct, these effects.
In August, 2000, WFPC2 began experiencinganomalous exposures in which the shutter failed to openproperly thus resulting in loss of occasional scienceimages. The problem was traced to an encoder wheel/phototransitor that senses the position of the shutter.This sensor is polled by the WFPC2 computer prior toeach exposure. In late August this sensor began tosporadically report that the “A” shutter blade was closedwhen, in fact, it was open. The WFPC2 computer, beingconfused about the shutters’ state, would then cancelthe exposure leading to a blank image. Since only about0.2% of the images were affected, we continued tooperate the camera while the problem wasbeing studied.
In late October we began seeing a more seriousproblem where two mis-readings in a row would lead tothe “A” shutter blade attempting to close, even thoughthe “B” blade was already closed, hence causing acollision of the two shutter blades. Since there wassome potential for this to damage the mechanism, wesuspended WFPC2 observations on 1 November 2000.
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Due to heroic efforts by people at GSFC, JPL,Lockheed, and STScI, a remedy was quickly found.It was noticed that, while the position sensor gave anincorrect reading when polled by the WFPC2 computer30 microseconds after activation, it did give the correctposition in a telemetry report taken 170 microsecondslater. While most of the WFPC2 programming wascoded in read-only memory, there are occasionalbranches to a small RAM area. The solution was to useone of these RAM branches to activate the shutterposition sensor 10 milliseconds before it is read by thecomputer thus giving the phototransitor more time torespond. The RAM patch was installed on November8th, and an extensive series of tests was run with nounexpected side effects being seen. Normal scienceobservations were resumed a few hours later, and nofurther shutter anomalies have been seen.
While the problem appears to have been mended, theexact cause is still not entirely clear. Much evidencepoints to radiation damage to the phototransistorcausing its response time to slow, while other evidencepoints to mechanical wear in the encoder wheel linkage,leading to misalignment of the wheel relative to thephototransistor. The problem continues to be investi-gated using archival WFPC2 data, telemetry data, andlaboratory tests of similar components, though so farthere is every reason to believe the problem willremain fixed.
Version 5 of the WFPC2 Instrument Handbook wasreleased in June, 2000 to support Cycle 10 proposers.This version includes new material on CTE, newgeometric/astrometric corrections, updated throughputvalues and photometric stability, new material on PSFsubtraction and aperture corrections as a function offield position, updated HST focus history, and currentinformation on observing strategies. It also containsperformance comparisons to ACS, NICMOS, and STIS.We anticipate releasing an updated version in June 2001to support Cycle 11 proposals.
Fine Guidance Sensors (FGS)Ed Nelan, [email protected]
All three of HST’s Fine Guidance Sensors areoperating nominally. The newest of the three,FGS2r, completed its first year in orbit in
December, 2000. Its performance and characteristicshave been monitored over this time. As expected,
desorption of water from its graphite-epoxy compositeshas changed the alignment of its interferometricelements with respect to the HST optical axis. This hascaused mild degradation of the instrument’s interfero-grams, but not by an amount that impairs its ability toacquire and track guide stars reliably. Furthermore, therate of change appears to have slowed significantly overthe last 4 months which builds confidence in ourexpectation that FGS2r will continue to provideexcellent service to the observatory.
FGS1r continues to perform well as HST’sastrometric science instrument. Recent modifications tothe flight software, which commands the instrument inits high angular resolution TRANSFER mode, hasenabled the use of scans as short as 0.3 arcsec to resolvevery close binary systems. This allows for more scans tobe completed in a given observing window therebyyielding the highest possible S/N ratio and effectivelyextending the use of this observing mode to objects asfaint as V = 16. (In the past longer scans were neededbecause the x and y axis fringes were not centered in thescan path.)
The data for two major calibration proposals forFGS1r were acquired in late December, 2000. These arethe optical distortion and the lateral color calibrations.The first calibrates an effect whereby the measuredrelative positions of stars in the FGS changes as the starfield is translated and/or rolled in the instrument’s fieldof view. The lateral color test calibrates the shift of astar’s measured position in the field of view as afunction of its color, a result of the beam having passedthrough refractive elements in the FGS1r optical train.Both of these tests could only be executed in theDecember 20 to December 26 time period when the sunangle on HST allowed for the use of unconstrainedtelescope roll angles. (They had originally beenscheduled for December 1999, but their execution wasprecluded by the servicing mission SM3A.) These datawill be analyzed by STScI and by members of theoriginal Astrometry Team at the University of Texas atAustin. When the analysis is completed, FGS1r will befully commissioned as a science instrument. And oncethe FGS calibration pipeline is updated to include theresults of these tests, all astrometry science dataacquired with FGS1r since the beginning of Cycle 8 canfinally be fully processed.
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Spectrographs GroupGerard Kriss, [email protected]
STIS continues to work well. We have beentracking the read noise in the STIS CCD, and ithas remained stable at 4.4 electrons for
GAIN=1. Our latest round of measurements of thecharge transfer efficiency (CTE), performed in the fallof 2000, indicate continued and significant deteriora-tion. Comparing the results to prior measurements, wesee that the CTE is decreasing by ~15% per year onaverage. Slight background levels of only a fewelectrons do significantly improve the CTE. As a result,broad-band imaging observations are not as seriouslyaffected as spectroscopic observations of faint objects.For observations of faint, compact targets, we now offerpseudo-apertures that place the target at a defaultposition closer to the end of the long slits (at row 900 onthe CCD). This can decrease CTE losses by up to afactor of 5. Full details on STIS CTE performance andthe use of the new pseudo-apertures are currentlyavailable in the Cycle 10 Phase 2 update (available onthe web), and they will be included in version 5.0 of theSTIS Instrument Handbook, to be released in June2001. Further analyses of CTE effects on imaging andspectroscopic observations of extended objects (e.g.,galaxies) are underway, and they will be reported asSTIS Instrument Science Reports on the web.
On-the-fly Calibration (OTFC) has been workingsmoothly since last June; soon STIS data will beavailable through the On-the-fly Reprocessing (OTFR)system. The principal benefit of OTFR will be theability to start with the first stage of raw data fileproduction. This will ensure that header parameters arecalculated and entered correctly, and it will also enableus to fix a number of problems evident in Time-Tag datafor STIS. These problems most notably include largejumps in the time series, gaps due to data losses that canbe prevented, and problems with data taken in observa-tions that experienced buffer wrap-arounds due to theBUFFER-TIME parameter being set incorrectly. Thefirst release of OTFR is expected in April 2001. Thisfirst release will incorporate the scattered-lightcorrection for STIS echelle-mode spectra that wasdescribed in the last newsletter. Software updates thatwill enable the time-tag data corrections is targeted forimplementation by June 2001.
HST Recent Release: A Bird's Eye View of a Galaxy Collision
What appears as a bird's head, leaning over to snatch up atasty meal, is a striking example of a galaxy collision inNGC 6745. The "bird" is a large spiral galaxy, with its corestill intact. It is peering at its "prey," a smaller passinggalaxy (nearly out of the field of view at lower right). Thebright blue beak and bright, whitish-blue top feathers showthe distinct path taken during the smaller galaxy's journey.These galaxies did not merely interact gravitationally asthey passed one another; they actually collided.
Image Credit: NASA and The Hubble Heritage Team(STScI/AURA)
Web Address: http://oposite.stsci.edu/pubinfo/pr/2000/34/
HST Recent Release:Hubble Peeks into a Stellar Nursery in a Nearby Galaxy
The Hubble telescope has peered deep into a neighboringgalaxy to reveal details of the formation of new stars.Hubble's target was a newborn star cluster within theSmall Magellanic Cloud, a small satellite galaxy of ourMilky Way. The picture shows young, brilliant stars cradledwithin a nebula, or glowing cloud of gas, cataloged asN 81.
Credit: NASA and The Hubble Heritage Team(STScI/AURA)
Web Address: http://oposite.stsci.edu/pubinfo/pr/2000/30/
Newsletter • Space Telescope Science Institute
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STScI Summer Student Program in 2000David Soderblom, SSP Coordinator, STScI
Twenty students came to the Institute last summer to work with our staffscientists on research projects for ten weeks. They came from a numberof U.S. colleges and universities, as well as from five other countries
(see the table below). We're looking forward to working with almost as many thisyear, with an even broader international representation. Those interested in theprogram can learn more by going to: http://www.stsci.edu/stsci/summer.shtml.
Name School STScI Supervisor
Jay Abbott Univ. Hertfordshire Brian Espey
Jules Blundell Liverpool John Moores David Soderblom
Milan Bogosavljevic Univ. Belgrade Massimo Robberto
Teddy Cheung Brandeis Univ. Meg Urry
Erin Claunch Virginia Military Inst. Massimo Stiavelli
Adam Fallon Macalester College Jeff Valenti
Michael Fine Colgate Univ. Mauro Giavalisco
Andrew Humphrey Univ. Hertfordshire Jerry Kriss
Lauren McCann MIT Melissa McGrath
Elizabeth McGrath Vassar College Kailash Sahu
Madeline Reed Columbia Univ. Antonella Nota
Rachel Scheinerman HS Megan Donahue
Joao Souza Leao UFSC Brazil Claus Leitherer
Rebecca Stanek Case Western Reserve Torsten Boeker
Chiharu Tanihata U. Tokyo Meg Urry
Mamie Thant HS Chris O’Dea
Richard Whitaker St. Andrews Keith Noll
Laura Whyte Univ. Hertfordshire Harry Ferguson
Diane Wong McGill Univ. Chris Blades
Brandon Woods HS Harry Ferguson
Summer Student Program 2000 Participants
Anne Kinney leavesSTScI for NASA
Anne Kinney left STScI lastyear to become OriginsTheme Director at NASA
Headquarters. Anne first came to theInstitute as an FOS post-doc in 1985and then became an AssistantAstronomer (and FOS InstrumentScientist) in 1988. She was promotedto Associate Astronomer with tenurein 1994.
Anne grew up in Lancaster,Wisconsin, where her father, a lawyer,would show her the constellations he'dlearned as a Navy navigator. Shereceived her bachelor's in physics andastronomy from the University ofWisconsin in 1975, spent a few yearsat the University of Copenhagen, andthen did a Ph.D. with Patrick Hugginsand Al Glassgold at New YorkUniversity. Her thesis looked at theBaldwin Effect in quasars in theultraviolet and in x-rays, and shefinsihed her degree in 1984. She wasbriefly a post-doc at NorthwesternUniversity before coming to STScI.
We bade Anne farewell last yearwith mixed feelings of sadness at herleaving and appreciation for what shehas done here and will do for thecommunity in her new role at NASA.
Steve Beckwith and Anne Kinney
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HST Recent Release: "X" Marks theSpot: Hubble Sees the Glow of StarFormation in a Neighbor Galaxy
The saying "X" marks the spot holdstrue in this Hubble telescope image.In this case, X marks the location ofHubble-X, a glowing gas cloud in oneof the most active star-forming regionsin galaxy NGC 6822. The galaxy lies1.6 million light-years from Earth inthe constellation Sagittarius, one of theMilky Way's closest neighbors. Thishotbed of star birth is similar to thefertile regions in the Orion Nebula inour Milky Way Galaxy, but on a vastlygreater scale. The intense star birth inHubble-X occurred about 4 millionyears ago, a small fraction of theapproximate 10-billion-year age ofthe universe.
Image Credit: NASA and The HubbleHeritage Team (STScI/AURA)
Web Address: http://oposite.stsci.edu/pubinfo/pr/2001/01/
Calendar
Cycle 11
Call for Proposals issued June, 2001 (tentative)
Phase 1 proposals due September 7, 2001 (firm)
Proposers notified December, 2001 (tentative)
Phase 2 Proposals Due February, 2002 (tentative)
Budgets Due February, 2002 (tentative)
Routine Observing Begins July, 2002 (tentative)
The Space Telescope —European Coordinating Facility publishesa quarterly newsletter which, althoughaimed principally at European SpaceTelescope users, contains articles ofgeneral interest to the HST community.If you wish to be included in the mailinglist, please contact the editor and stateyour affiliation and specific involvementin the Space Telescope Project.
Robert Fosbury (Editor)Space Telescope —European Coordinating Facility
Karl Schwarzschild Str. 2D-85748 Garching bei MünchenFederal Republic of Germany
E-Mail: [email protected]
ST-ECFNewsletter
Space Telescope Users Committee April 19-20, 2001
Servicing Mission 3B Launch November 29, 2001 (tentative)
Astronomer’s Proposal Tools .............................................. 1
Director’s Perspective .......................................................... 2
ST ScI Electronic Grants Management System .................. 3
Multi-Mission Archive at theSpace Telescope Science Institute (MAST) News .............. 4
The Next Generation Space Telescopeat the beginning of a new millennium ................................. 6
NGST Town Hall at 198th AAS Meeting in Pasadena ........ 8
The Cycle 10 Review Process ............................................. 9
Cycle 10 Statistics ............................................................. 11
Cycle 10 Approved Observing Programs .......................... 14
PyRAF: a Python-based command language for IRAF .... 19
Project Scientist’s Report .................................................. 20
Instrument NewsAdvanced Camera for Surveys (ACS) .............................. 21
Near-Infrared Cameraand Multi-Object Spectrometer (NICMOS) ...................... 21
WFPC2 .............................................................................. 22
Fine Guidance Sensors (FGS) ........................................... 24
Spectrographs Group ......................................................... 25
Calendar ............................................................................. 27
How to contact us .............................................................. 28
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Contents How to contact us:First, we recommend trying our Web site: http://www.stsci.eduYou will find there further information on many of the topicsmentioned in this issue.
Second, if you need assistance on any matter send e-mail [email protected] or call 800-544-8125. International callers mayuse 1-410-338-1082.
Third, the following address is for the HST Data Archive:[email protected]
Fourth, if you are a current HST user you may wish to addressquestions to your Program Coordinator or Contact Scientist;their names are given in the letter of notification you receivedfrom the Director, or they may be found on the Presto Web pagehttp://presto.stsci.edu/public/propinfo.html.
Finally, you may wish to communicate with members of theSpace Telescope Users Committee (STUC). They are:
George Miley (chair), Sterrewacht Leiden,[email protected]
Marc Davis, U.C. BerkeleyJames Dunlop, Royal Obs. EdinburghDebbie Elmegreen, Vassar CollegeHolland Ford, JHUSuzanne Hawley, U. WashingtonChris Impey, U. ArizonaJohn Kormendy, U. Texas, AustinDave Sanders, U. HawaiiKarl Stapelfeldt, JPLJohn Stocke, U. ColoradoAndré Vidal-Madjar, CNRS, Paris
The Space Telescope Science Institute Newsletter is editedby David Soderblom, to whom correspondence may be sent([email protected]). To record a change of address or to requestreceipt of the Newsletter, please contact Ms. Nancy Fulton([email protected]).
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