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THE ISO HANDBOOKVolume III:LWS –The Long Wavelength SpectrometerCécile Gry1, Bruce Swinyard2, Andrew Harwood2, Norman Trams3, SarahLeeks4 , Tanya Lim2, Sunil Sidher2, Christopher Lloyd2, Stefano Pezzuto5,Sergio Molinari5, Rosario Lorente1, Emmanuel Caux6, Edward Polehampton7,Josephine Chan2, Gerard Hutchinson2, Thomas Müller8, Martin Burgdorf9,and Timothy Grundy2SAI-99-077/Dc, Version 2.1June, 20031ISO Data Centre, Science Operations and Data Systems Division, Research and Scientific SupportDepartment of ESA, Villafranca del Castillo, P.O. Box 50727, E-28080 Madrid, Spain2Rutherford Appleton Laboratory, Chilton, Didcot OX11 OQX Oxfordshire, UK3Science Operations and Data Systems Division of ESA/ESTEC, Keplerlaan 1, Postbus 299, 2200 AGNoordwijk, The Netherlands4Herschel Science Centre, Research and Scientific Support Department of ESA, ESTEC, Keplerlaan 1,Postbus 299, 2200 AG Noordwijk, The Netherlands5IFSI-CNR, Via Fosso del Cavaliere 100, 00133 Roma , Italy6CESR, BP4346, 31028 Toulouse Cedex 4, France7Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany8Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany9SIRTF Science Center, California Institute of Technology, 220-6, Pasadena, CA91125, USA
iiDocument InformationDocument:Volume:Title:Reference Number:Issue:Issue Date:Authors:Editors:Web-Editor:The ISO HandbookIIILWS – The Long-Wavelength SpectrometerSAI/99-077/DcVersion 2.1June 2003C. Gry, B. Swinyard, A. Harwood et al.T. Müller, J. Blommaert & P. Garcı́a-LarioJ. MatagneDocument HistoryThe ISO Handbook, Volume III: LWS – The Long Wavelength Spectrometer, is based on the followingdocuments: The ISOLWS Data Users Manual (SAI/95-219/Dc, Issue 5.0 June 1, 1998), N. Trams, using inputsfrom: M. Burgdorf, C. Gry, T. Lim, S. Pezzuto, A. Harwood, S.J. Leeks, P.E. Clegg, B. Swinyard,K. King, S. Lord, S. Unger. The LWS observer’s manual (Issue 1.0, March 1994, LWS/PEC/2038.01), prepared by the LWSconsortium and written by: P.E. Clegg, A. Heske, N.R. Trams. The Addendum to the LWS OBSERVER’S MANUAL (SAI/96-166/Dc, Version 1.0, 5 August1996), N.R. Trams, P.E. Clegg and B.M. Swinyard.and many articles and reports which are referenced in the corresponding sections and listed in the Bibliography.Document Change RecordDateRevisionComments31/12/99Draft 1.0Initial Draft for comments11/02/00Version 1.0First Version of the ISO Handbook, Volume IV:LWS – The Long-Wavelength Spectrometerrelated to OLP 8.6 data productsNovember 2000Version 1.1updateJune 2001Version 1.2update, related to OLP 10.0 data productsAugust 2002Version 2.0update, now Volume IIIJune 2003Version 2.1update, printed version
iiiAcknowledgementsThe following pages list the many people and teams who have contributed to the development, the operations, the science planning, the data-analysis and the calibration of the LWS.The information contained in this handbook results from their work.LWS Instrument Principal Investigator:Peter Clegg (QMW London)The LWS was conceived and built in the following institutes:Rutherford Appleton Laboratory (RAL), Didcot, UKQueen Mary and Westfield College (QMW), London, UKUniversity College London (UCL), London, UKLaboratoire d’Astronomie Spatiale (LAS), Marseille, FCentre d’Etude Spatiale des Rayonnements (CESR), Toulouse, FIstituto di Fisica dello Spazio Interplanetario (IFSI), Roma, INaval Research Laboratory (NRL), USA.
ivLWS Instrument ConsortiumPeter AdeJean-Paul BaluteauMike BarlowJean-Claude BergesEmmanuel CauxCecilia CeccarelliRicardo CerulliSarah ChurchPeter CleggFrancis CotinPierre CoxPaul CruvellierGary DavisRoger EmeryJackie FischerIan FurnissBill GlencrossMatt GreenhouseMatt GriffinCécile GryMartine JoubertKen KingRene LiseauDario LorenzettiDavid NaylorBrunella NisiniAlain OmontRenato OrfeiDaniel PéquinotDominique PouliquenN’Guyen Quang RieuDavid RobinsonMichel SaissePaolo SaracenoGuy SerraHoward SmithLuigi SpinoglioBruce SwinyardBill TowlsonGlenn WhiteQMW LondonObs. MarseilleUCL LondonLAS MarseilleCESR ToulouseIFSI FrascatiIFSI FrascatiUC BerkleyQMW LondonCESR ToulouseObs. MarseilleLAS MarseilleU. SaskatchewanRAL DidcotNRL WashingtonUCL LondonUCL LondonNASM WashingtonQMW LondonLAS MarseilleCNES ParisRAL DidcotObs. StockholmIFSI FrascatiU. LethbridgeIFSI FrascatiObs. GrenobleIFSI FrascatiObs. ParisLAS MarseilleObs. ParisQMW LondonLAS MarseilleIFSI FrascatiCESR ToulouseNASM WashingtonIFSI FrascatiRAL DidcotUCL LondonQMW LondonThe LWS Standing Committee for ScienceNamePeter CleggRoger EmeryMartine JoubertPaolo SaracenoHoward SmithRepresenting(PI, Chairman)(UK)(France)(Italy)(USA)
vSpecialist Astronomy GroupsGroupSolar System (SS)The ISM (ISM)Pre-Main-Sequence Evolution (Pre-MS)Post-Main-Sequence Evolution (Post-MS)Extragalactic Studies (Xgal)LeaderDavid Naylor/Gary DavisJean-Paul BaluteauPaolo SaracenoMike BarlowHoward SmithLWS ConsultantsSAGConsultantAffiliationSSSimon CalcuttDaniel GautierGlenn OrtonPer AnnestadJoseph CassinelliJosé CernicharoEd ChurchwellAlain LégerSteve MillerJonathan TennysonHelen WalkerPhillipe AndréMartin CohenFrancesco PallaMartin CohenJim CohenChris SkinnerHelen WalkerMatt MalkanJonathan McDowellChris SkinnerGordon StaceySteven LordSean ColganMichael HaasU. OxfordObs. ParisJPL PasadenaU. ArizonaU. WisconsinIEM-CSICU. WisconsinIAS OrsayUCL LondonUCL LondonRAL DidcotSaclayUC BerkeleyObs. ArcetriUC BerkeleyNRAL Jodrell BankUCL LondonRAL DidcotUC Los AngelesSAO BostonUCL LondonU. -MSXGalCalibrationProgrammeIB. Study of ionised regionsIV. Abundance gradientsIA Neutral interstellar gasIV. Abundance gradientsIIA. Interstellar cirrusIA Neutral interstellar gasIA Neutral interstellar gasIA. Interstellar cirrus
viDevelopment PhasePeter AdePhillipe AndréPer AnnestadJean-Paul BaluteauMike BarlowJean-Claude BergesMark BuckleyMartin BurgdorfJohn CathrewSimon CalcuttJoseph CassinelliEmmanuel CauxCecilia CeccarelliJosé CernicharoRicardo CerulliJean-Paul ChabaudSarah ChurchEd ChurchwellPeter CleggJim CohenMartin CohenSean ColganFrancis CotinPierre CoxPaul CruvellierGary DavisQMWSaclayU. ArizonaLASUCLLASRALESARALU. OxfordU. WisconsinCESRIFSIIEM-CSICIFSICESRQMWU. WisconsinQMWNRAL Jodrell BankUC BerkeleyNASA/AmesCESRObs. MarseilleLASMSSLChristophe DeletrezTrevor DimbylowBrian DiplockAuriel DonkinDuncan DrummondEric DunfordCESRRALRALRALRALRALRoger EmeryDavid EwartJacqueline FischerIan FurnissDaniel GautierBill GlencrossPeter GrayMatt GriffinPhil GriffithsCécile GryMichael HaasAndrew HarwoodPhil HingstonJohn HolmesMartine JoubertRALRALNRLUCLObs. ParisUCLRALQMWRALLASNASA AmesRALRALMSSLLASKen KingRALDetector development, Guaranteed time programmeScientific consultantScientific consultantFrench Project Scientist, Guaranteed time programmeGuaranteed time programmeDesign of optics and mechanical assemblyDiagnostics software developmentPreparation of PV phaseProduct assuranceScientific consultantScientific consultantWarm electronics development, Guaranteed time programmeOn-Board software development, Guaranteed time programmeScientific consultantDigital processing unit electronics engineeringWarm electronics developmentDetector characterisationScientific consultantPrincipal Investigator LWS, Guaranteed time programmeScientific consultantScientific consultantScientific consultantWarm analogue electronics managementGuaranteed time programmeDirector of LASFabry-Pérot development manager, Guaranteed timeprogrammeFPU simulator electronics engineeringRTA/QLA Software designMechanical engineer, Cold vibration facility engineeringProject office administrationEGSE electronics/software engineeringHead of RAL Space Science Department,Liaison with SERC/PPARCProject scientist, Guaranteed time programmeAIT test controller, Scientific consultantGuaranteed time programmeFabry-Pérot design scientist, Guaranteed time programmeScientific consultantFabry-Pérot development, Guaranteed time programmeOptics designDetector development, Guaranteed time programmeProduct assuranceGuaranteed time programmeScientific consultantSoftware development, QLA and pipelineAIV operationsFabry-Pérot assembly developmentFrench Project Scientist, Optics development management,Guaranteed time programmeEGSE Development, Operations scientist,Guaranteed time programme
viiAlain LégerKate LidiardTanya LimRené LiseauJudy LongSteve LordDario LorenzettiMatt MalkanJonathan McDowellSteve MillerSergio MolinariDavid NaylorBrunella NisiniKeith NormanAlain OmontRenato OrfeiIAS OrsayRALRALIFSI / Obs. StockholmRALIPACIFSIUC Los AngelesSAO BostonUCLIFSIU. CalgaryIFSIMSSLObs. GrenobleIFSIGlenn OrtonFrancesco PallaTom PatrickDaniel PéquignotDominique PouliquenMark PriceN’Guyen Quang RieuAlan RogersDavid RobinsonJPLObs. ArcetriMSSLObs. ParisLASQMWObs. ParisRALQMWTony RushMichael SaissePaolo SaracenoLakshmi SastryGuy Serra*RALLASIFSIRALCESRRoger SideySunil SidherCuston DevelopmentRALChris Skinner*Alan SmithHoward SmithLuigi SpinoglioPhil SpurrettGordon StaceyBruce SwinyardUCLRALNRLIFSIRALU. CornellRALJonathan TennysonDamien TexierBill TowlsonNorman TramsDerek VickersHelen WalkerYvonne WindsorGlenn WhiteUCLESAUCLESAQMWRALBNSCQMWScientific consultantOptics design engineeringDiagnostics software development, Scientific consultantGuaranteed time programmeProject office administration, Party organisationScientific consultantGuaranteed time programmeScientific consultantScientific consultantScientific consultantOperations preparation, Scientific consultantFabry-Pérot development, Guaranteed time programmeGuaranteed time programmeFabry-Pérot development managerGuaranteed time programmeDPU electronic design, development management,Guaranteed time programmeScientific consultantScientific consultantFabry-Pérot wheel mechanical designGuaranteed time programmeOptics design engineeringDetector testingGuaranteed time programmeLWS Project ManagementDetector development management,Product Assurance, Quality AssuranceProduct Assurance, Quality AssuranceOptics DesignItalian Project Scientist, Guaranteed time programmeSoftware engineeringWarm electronics development, Guaranteed timeprogrammeFabry-Pérot wheel motor designSoftware engineering calibration pipeline, ScientificconsultantScientific consultantAIV facility development, operations and managementUS Project Scientist, Guaranteed time programmeGuaranteed time programmeAIV testingScientific consultantInstrument testing and calibration, PV phase preparation,Guaranteed time programmeScientific consultantPreparation of LIDTFabry-Pérot DevelopmentOperations preparation, Scientific consultantDetector/Focal Plane engineeringScientific consultantBNSC executiveGuaranteed time programme
viiiOperations PhasePeter AdeChristiane ArmandJean-Paul BaluteauMike BarlowMark BuckleyMartin BurgdorfEmmanuel CauxQMWLASLASUCLRALESACESRCecilia CeccarelliPeter CleggMartin CohenCarlos CorreiaPierre CoxGary DavisAnna di GiorgioRoger EmeryDavid EwartJacqueline FischerIan FurnissBill GlencrossMatt GreenhouseGriffin MattU. GrenobleQMWUC BerkelyQMWObs. MarseilleCécile GryLAS/ESAAndrew HarwoodMartine JoubertKen KingSarah LeeksTanya LimRALRALQMWRAL/ESARené LiseauXiao-Wei LiuJudy LongSteve LordDario LorenzettiRosario LorenteNigel MinchinSergio MolinariObs. StockholmUCLRALIPACIFSIESAQMWIFSI/IPACDavid NaylorBrunella NissiniGraeme OldhamAlain OmontTom PatrickDaniel PéquinotStefano PezzutoMark PriceN’Guyen Quang RieuU. LethbridgeIFSIQMWObs. GrenobleMSSLObs. ParisIFSIQMWObs. ParisIFSIRALRALNRLUCLUCLSmithsonian NASMQMWScience analysisLIDT member, wavelength calibrationScience analysisScience analysisSoftware development, calibration analysisLIDT member, calibration uplink, photometric calibrationCalibration analysis, Science analysis,Parallel and serendipity mode concept and implementationScience analysisPrincipal Investigator LWS, Science analysisCalibration analysisCalibration analysis, Science analysisScience analysisFabry-Pérot calibration analysis, Science analysisLIDT member, wavelength calibration, Science analysisLWS Project Scientist, Science AnalysisLIDT member, trend analysis, RTA/QLA expertScience analysisScience analysisScience analysisScience analysisInstrument commissioning, Calibration analysis, ScienceanalysisLIDT member, wavelength calibration, grating profile,Science analysisOLP software developmentScience analysisProject managerDetector analysis, Science analysisLIDT deputy leader, photometric calibration, RSRF,Science analysisScience analysisCalibration analysis, Science analysisProject office administration, Party organisationCalibration analysis, ISAP development, Science AnalysisScience analysisCalibration analysis, grating profileCalibration analysis, blues performer, Science analysisLIDT member, photometric calibration, beamcharacterisation, Science analysisScience analysisScience analysisCalibration analysis, Science analysisScience analysisDiagnostic wheel engineeringScience analysisLIDT member, Fabry-Pérot calibration, Science analysisLIDT member, detector calibration, trend analysisScience analysis
ixPaolo SaracenoSunil SidherIFSIRALAlan SmithHoward SmithLuigi SpinoglioBruce SwinyardRALNASMIFSIRALRoger SylvesterDamien TexierElisabetta TommasiNorman TramsSarah UngerGlenn WhiteUCLESAIFSIESARAL/IPACQMWScience analysisLIDT member, calibration analysis, community support,LIA/ISAP development, Science analysisOperations supportCalibration analysis, Science analysisScience analysisUK LWS team leader, Instrument comissioning,Calibration analysis, LIA/ISAP development, Science analysisCalibration analysis, Science analysisLIDT leader, trend analysisLIDT member, wavelength calibration, Science analysisLIDT/SOC member, Fabry-Pérot calibrationISAP development, Community support, Science analysisScience analysisPost-Operations PhaseMartin BurgdorfSusana Cabinero Rodrı́guezEmmanuel CauxJosephine ChanPeter CleggRoger EmeryDavid EwartCécile GryAndrew HarwoodGerard HutchinsonKen KingSarah LeeksTanya is LloydJudy LongSteve LordPhillippe MartySergio MolinariHuw MorrisThomas MüllerEdward PolehamptonSunil SidherBruce orence VivaresCESRPhotometric calibrationSerendipity mode analysisTransient correctionScientific validation, Photometric calibrationLWS Principal InvestigatorLWS Project ScientistComputer systems supportHandbook editor, Grating resolution elementOLP software developmentLIA development, Fabry-Pérot calibrationUKIDC managerDetector characterisationParallel and serendipity mode calibration, RSRF,LWS project managerBeam characterisation, de-fringingProject office administration, Party organisationISAP development, Calibration analysisTransient correction, LIA developmentISAP/LIA developmentComputer system managerCalibration analysisFabry-Pérot calibrationLIA development, Photometric calibrationLWS project manager, Photometric calibration, opticalmodellingParallel and serendipity mode pipeline development
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ContentsList of FiguresxviiList of Tablesxix1 Introduction11.1Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11.2Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11.3How to Contact Us . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11.4LWS Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21.4.1Acknowledgements and guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . .21.4.2Inventory of ISO publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22 Instrument Overview52.1Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52.2Overall Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52.3The LWS Optics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52.4The Grating Spectrometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82.5The Fabry-Pérot Spectrometers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .142.6The LWS Detectors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17LWS readout electronics (integrating amplifiers) . . . . . . . . . . . . . . . . . . .202.6.1.1The ramps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22Particle hits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .232.6.12.6.23 Instrument Modes and Observing Templates253.1Summary of the Observing Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .253.2Description of the Observing Modes: the Astronomical Observation Templates (AOTs) . .263.33.2.1Medium-resolution wavelength range (AOT L01) . . . . . . . . . . . . . . . . . . .263.2.2Medium-resolution line spectrum (AOT L02) . . . . . . . . . . . . . . . . . . . . .273.2.3Narrow-band photometry (AOT L02) . . . . . . . . . . . . . . . . . . . . . . . . .273.2.4High-resolution wavelength range (AOT L03) . . . . . . . . . . . . . . . . . . . . .273.2.5High-resolution line spectrum (AOT L04) . . . . . . . . . . . . . . . . . . . . . . .273.2.6Parallel and serendipity modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27History of AOT Changes throughout the Mission . . . . . . . . . . . . . . . . . . . . . . .28xi
CONTENTSxii4 Data Processing314.1Processing Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .314.2Quality Check of the Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .354.3Derive-SPD Processing Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .354.3.1Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .354.3.2Construction of ramps and discarding unusable readouts . . . . . . . . . . . . . . .364.3.3Conversion of readouts to voltages . . . . . . . . . . . . . . . . . . . . . . . . . . .364.3.4Flag saturated ramps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .374.3.5First level deglitching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .374.3.5.1Introduction to glitches and spikes . . . . . . . . . . . . . . . . . . . . . .374.3.5.2Detection method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .374.3.5.3Patterns expected from spikes and glitches . . . . . . . . . . . . . . . . .394.3.5.4Glitch handling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .404.3.6Extraction of ramp slopes and conversion to photocurrent . . . . . . . . . . . . . .414.3.7Illuminator processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42Auto-Analysis Processing Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .424.4.1Absolute responsivity correction and responsivity drift correction . . . . . . . . . .424.4.1.1Grouping of data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .434.4.1.2Absolute responsivity correction . . . . . . . . . . . . . . . . . . . . . . .434.4.1.34.44.5Responsivity drift correction . . . . . . . . . . . . . . . . . . . . . . . . .474.4.2Dark current/background straylight subtraction . . . . . . . . . . . . . . . . . . . .484.4.3Grating scan wavelength calibration . . . . . . . . . . . . . . . . . . . . . . . . . .494.4.4Grating spectral responsivity calibration . . . . . . . . . . . . . . . . . . . . . . . .504.4.5Spectral bandwidth correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . .504.4.6Fabry-Pérot scan wavelength calibration . . . . . . . . . . . . . . . . . . . . . . . .504.4.7Fabry-Pérot throughput correction . . . . . . . . . . . . . . . . . . . . . . . . . . .514.4.8Velocity correction to wavelength . . . . . . . . . . . . . . . . . . . . . . . . . . . .514.4.9Write LSNR data product (only in OLP versions earlier than 8) . . . . . . . . . .524.4.10 Calculation of uncertainties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .524.4.10.1 Grating continuum flux error estimation . . . . . . . . . . . . . . . . . . .524.4.10.2 Fabry-Pérot continuum flux error estimation . . . . . . . . . . . . . . . .52Processing of the Parallel and Serendipity Modes . . . . . . . . . . . . . . . . . . . . . . .544.5.154Dark current subtraction and drift removal . . . . . . . . . . . . . . . . . . . . . .5 Calibration and Performance5.15.2Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5757Absolute Flux Calibration and Grating Relative Response . . . . . . . . . . . . . . . . . .575.2.1Absolute flux calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .595.2.2Relative spectral response function . . . . . . . . . . . . . . . . . . . . . . . . . . .60Fabry-Pérot Flux Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .615.4Dark Current Determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .625.5In-orbit Sensitivity of the LWS – Detector Performance . . . . . . . . . . . . . . . . . . .635.3
CONTENTS5.65.75.85.9xiiiPhotometric Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.6.1 Calibration sources used for photometric purposes . . . . . . . . . . . . . . . . . .65655.6.2LWS photometric stability checked with observations of Mars . . . . . . . . . . . .665.6.3Comparison with IRAS fluxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.6.3.1 Sample selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67675.6.3.2Corrections applied . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .685.6.3.3Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .695.6.4 Checking the Fabry-Pérot photometric accuracy . . . . . . . . . . . . . . . . . . .The Strong Source Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71715.7.1The reason for the correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .715.7.2The correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .725.7.3 Future . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Quarter-Second Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73755.8.1LW5: quarter- versus half-second processing . . . . . . . . . . . . . . . . . . . . . .755.8.2 Summary of processing for various strength sources . . . . . . . . . . . . . . . . . .Instrumental Field of View: The Beam Profile . . . . . . . . . . . . . . . . . . . . . . . . .77775.9.1The beam profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .785.9.2Asymmetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .795.9.35.9.4Flux correction for extended sources . . . . . . . . . . . . . . . . . . . . . . . . . .Extended source flux per unit area . . . . . . . . . . . . . . . . . . . . . . . . . . .81815.9.5Effect of the ISO PSF at large distances: check of the straylight around Jupiter . .835.10 Grating Wavelength Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .855.10.1 Basic principles and calibration strategy . . . . . . . . . . . . . . . . . . . . . . . .5.10.2 Calibration sources and types of observations . . . . . . . . . . . . . . . . . . . . .85855.10.3 Detector angles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .855.10.4 Time dependence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.10.5 Assessment of the achieved wavelength accuracy . . . . . . . . . . . . . . . . . . .85875.11 Grating Resolution and Characterisation of the Line Profiles. . . . . . . . . . . . . . . .885.11.1 Preparation of the data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .885.11.2 Stability of the line profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.11.3 Characteristics of the profiles. Comparison to Gaussians. . . . . . . . . . . . . . .89905.11.4 Effect of a lower spectral sampling . . . . . . . . . . . . . . . . . . . . . . . . . . .925.12 Fabry-Pérot Wavelength Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .925.12.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.12.2 Strategy of calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92925.12.2.1 The line fitting algorithms . . . . . . . . . . . . . . . . . . . . . . . . . .935.12.3 Calibration for OLP Version 10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.12.4 Monitoring the Fabry-Pérot wavelength calibration . . . . . . . . . . . . . . . . . .93945.12.4.1 Results for FPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .965.12.4.2 Results for FPL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .965.12.5 Fabry-Pérot wavelength accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.13 Fabry-Pérot Resolution and Line Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . .9699
CONTENTSxiv5.14 Accuracy of the Parallel and Serendipity Mode Calibration . . . . . .5.14.1 Prime mode observations coincident with parallel observations5.14.2 Comparison with prime mode from stabilisation periods . . . .5.14.3 Comparison between overlapping parallel rasters . . . . . . . .5.14.4 Comparison with other instruments . . . . . . . . . . . . . . .6 Caveats and Unexpected Effects6.1 Glitches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.2 Response to Off-axis and Extended Sources: Fringes in the Data .6.3 Response to Off-axis and Extended Sources: Spectrum Fracturing6.4 Dark Current Subtraction . . . . . . . . . . . . . . . . . . . . . . .6.5 Differences between Overlapping Sub-spectra . . . . . . . . . . . .6.6 Spurious Features Introduced by the RSRF . . . . . . . . . . . . .6.7 The Near-IR Leak . . . . . . . . . . . . . . . . . . . . . . . . . . .6.8 ‘Detector Warm-up Features’ in the Long Wavelength Detectors .6.9 Transients and Memory Effects . . . . . . . . . . . . . . . . . . . .6.9.1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . .6.9.2 The correction procedure . . . . . . . . . . . . . . . . . . .6.10 Detector Non-linearity: the Strong Source Correction . . . . . . . .6.10.1 Does your data require the correction? . . . . . . . . . . . .6.10.2 Getting the correction applied to your data . . . . . . . . .6.11 57.16 µm SW2 Feature in the Fabry-Pérot Spectra . . . . . . . . .6.12 FP Wavelength Calibration . . . . . . . . . . . . . . . . . . . . . .6.13 Removal of the Grating Resolution Element in FP Observations . .6.14 Use of ‘Non-prime Data’ in FP Observations . . . . . . . . . . . .6.15 Side Order Contamination in FP Data . . . . . . . . . . . . . . . .6.16 Responsivity Drift in Long FP Observations . . . . . . . . . . . . .7 Guide to Instrument Related Data Products7.1 Inventory and Naming Convention . . . . . . . . . . . . . . . . . . .7.2 Product Files – Description of Content and Use . . . . . . . . . . . .7.2.1 Timing information in the products: the ITK . . . . . . . . .7.2.2 General FITS header keywords for LWS data . . . . . . . . .7.2.3 Transparent data . . . . . . . . . . . . . . . . . . . . . . . . .7.2.4 Edited Raw Data (ERD files) . . . . . . . . . . . . . . . . . .7.2.4.1 LSTA: The LWS Compact Status History . . . . . .7.2.4.2 LIER: LWS illuminator ERD file . . . . . . . . . . .7.2.4.3 LGER: LWS grating ERD file . . . . . . . . . . . .7.2.4.4 LSER: LWS short-wavelength Fabry-Pérot ERD file7.2.4.5 LLER: LWS long-wavelength Fabry-Pérot ERD file7.2.4.6 LWHK: LWS housekeeping ERD file . . . . . . . . .7.2.5 Standard Processed Data (SPD product files) . . . . . . . . .7.2.5.1 LSPD: LWS standard processed data . . . . . . . . 99. 99. 100. 101. 7138139143143.
CONTENTS7.2.67.2.77.2.87.3xv7.2.5.2LIPD: LWS illuminator processed data file . . . . . . . . . . . . . . . . . 1477.2.5.3LWGH: LWS Glitch History file . . . . . . . . . . . . . . . . . . . . . . . 1487.2.5.4LPSP: LWS parallel Standard Process Data7.2.5.5LSSP: LWS serendipity Standard Process Data . . . . . . . . . . . . . . . 149. . . . . . . . . . . . . . . . 149LSPD and LIPD status words . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1507.2.6.1Detector status word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1507.2.6.2Mechanism status word . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151Auto-Analysis results (AAR product files) . . . . . . . . . . . . . . . . . . . . . . . 1517.2.7.1LSAN: LWS Auto-Analysis results . . . . . . . . . . . . . . . . . . . . . . 1517.2.7.2LSNR: LWS Auto-Analysis results without responsivity correction . . . . 1547.2.7.3LIAC: LWS illuminator summary file . . . . . . . . . . . . . . . . . . . . 1547.2.7.4LSCA: LWS scan summary file . . . . . . . . . . . . . . . . . . . . . . . . 1557.2.7.5LGIF: LWS Group Information File . . . . . . . . . . . . . . . . . . . . . 1567.2.7.6LPAA: LWS parallel Auto-Analysed data . . . . . . . . . . . . . . . . . . 1577.2.7.7LSAA: LWS serendipity Auto-Analysed data . . . . . . . . . . . . . . . . 1577.2.7.8LPAD: LWS parallel averaged data . . . . . . .
Title: LWS { The Long-Wavelength Spectrometer Reference Number: SAI/99-077/Dc Issue: Version 2.1 Issue Date: June 2003 Authors: C. Gry, B. Swinyard, A. Harwood et al. Editors: T. M uller, J. Blommaert & P. Garc a-Lario Web-Editor: J. Matagne Document History The ISO Handbook, Volume III: LWS { The Long Wavelength Spectrometer, is based on the .
