LAMOST波长定标和在线数据处理系统的研究的中期报告

LAMOST波长定标和在线数据处理系统的研究的中期报告Introduction:LAMOST(LargeSkyAreaMulti-ObjectFiberSpectroscopicTelescope)isoneofthemostsignificantastronomicalprojectsinChina,aimingtocarryoutacomprehensivespectroscopicsurveyoftheMilkyWayanddistantgalaxies.Theprimaryobjectiveoftheprojectistomapmillionsofstarsandgalaxiesinouruniverseusingthelargestmulti-fiberspectroscopictelescopeintheworld.TheLAMOSTprojectproducesanenormousamountofdataeveryyear.Thetotalamountofdataexpectedtobecollectedbythetelescopeisestimatedtobemorethan20petabytesoveraten-yearperiod.Therefore,developinganautomateddataprocessingsystemandtoolstohandlethevastamountofdatabecomesacrucialtask.Inthisreport,wepresentthecurrentresearchprogressofLAMOSTwavelengthcalibrationandonlinedataprocessingsystem,whichaimstoprovideareliableandaccuratecalibrationoftheobservatory'sspectraandmakethedataprocessingmoreefficientandseamless.WavelengthCalibration:Theprimarypurposeofwavelengthcalibrationistoobtainanaccurateandconsistentrelationshipbetweenthepixelsonthedetectorandthewavelengthsofthespectra.Wavelengthcalibrationisavitalstepbecauseitaffectsmanyotheraspectsofthedataanalysissuchasradialvelocitymeasurementandspectralclassification.Toachievethisgoal,theLAMOSTresearchgrouphasdevelopedapipelinesystemthatperformsthefollowingtasks:1.SpectralExtraction:Thefirststepinvolvesidentifyingthebrighteststarsineachfiberbundleandextractingtheirspectra.Theextractedspectraarethenpreprocessed,andthesignal-to-noiseratioiscalculated.2.ThArCalibration:WhileThArlampshavebeenusedasacalibrationsourceinvarioustelescopes,itsmethodisparticularlyeffectiveforLAMOST.Tocalibratethespectra,theLAMOSTresearchgroupusesaThArlamptocreateareferencespectrumthatisusedtoestablishtherelationshipbetweenthepixelsandwavelengths.Thisprocessistime-consumingandrequirescarefultuningoftheparameters.3.OffsetCorrection:Thequalityofthecalibrationlampcanbeaffectedbyvariousfactorssuchastemperatureandpressure.Moreover,instrumentnoiseandstabilitycanalsoaffectthequalityofthecalibration.Therefore,anoffsetcorrectionalgorithmisrequiredtoensurethequalityofthecalibration.4.LineIdentificationandFitting:Aftercalibration,thesystemdetectsthespectrallineswithhighaccuracyandfitsthemtoapolynomialfunctiontocreateareferencespectrum-map.Itthenusesthemaptoconvertpixelpositionstowavelengthscorrespondingtospecificspectrallines.Currently,theLAMOSTresearchgrouphasachievedanaveragecalibrationaccuracyoflessthan0.1Å,whichisaremarkableachievementconsideringthesignificantchallengesinvolvedinachievingit.OnlineDataProcessingsystem:TheLAMOSTdataisenormous,andthevolumeistoolargetobeprocessedmanually.Therefore,anautomatedonlinedataprocessingsystemisdevelopedtohandlethisdataeffectivelyandefficiently.Thesystemcomprisesseveralcomponents,someofwhichare:1.DataStorageSystem:Thetelescopecollectsandstoresdataonapetabyte-scale.Therefore,thestoragesystemusedmustbescalable,cost-effective,andreliable.2.DataPreprocessingSystem:Thissystemextractsandcleanstherawdataintousableformats.Datapreprocessingincludesspectralextraction,wavelengthcalibration,andpre-processingtoimprovethesignal-to-noiseratio.3.PipelineProcessingSystem:Thissystemcarriesoutthecoredataprocessingtaskssuchascross-correlation,radialvelocitymeasurement,andspectralclassification.4.DataQueryingSystem:Thissystemallowsresearcherstoquerytheprocesseddatabasedonspecificcriteriasuchasobjecttype,radialvelocity,andspectralfeatures.Currently,theLAMOSTdataprocessingsystemcanprocessupto7,000spectraperday,anditstoresupto200millionspectrainitsdatabase.Thesystemincludesaweb-basedinterfacethatallowsuserstoaccesstheirdataeasily.Conclusion:Inconclusion,theLAMOSTwavelengthcalibrationandonlinedataprocessingsystemhavemadesignificantprogressinproducingaccuratespectraandhandlingthevastamountsofdatageneratedbythetel