Post on 19-Jul-2020
transcript
Tes$ngonZoombandmodeinDiFX
HiroakiNishiokaIns$tuteofAstronomyand
Astrophysics,AcademiaSinica(ASIAA)
GreenlandTelescope(GLT)• ConstructaVLBIsta$onatasummitsta$oninGreenland• ProjectteamconsistsofASIAA,SAO,MITHaystackand
NRAO• PartneroftheEventHorizonTelescope(EHT)andALMA
PhasingProject(APP)• Aimingatadirectimagingoftheshadowofthesupper
massiveblackholeinM87• ALMA-NAprototype12mantenna• 230,350GHzfrequencyforVLBI,THzforsingle-dishuse• Retrofi\ngongoingfortheextremelycoldtemperature
(-50deg)• CommissioningandfirstlightatThulein2016-2017
SubmmVLBIwithGLT
Thelongestbaselineof9000kmAchieveangularresolu$onof20mas(M87BHshadow40mas)with350GHz.
AntennatestinSocorro(2012)
• Antennare-tes$ng• Por$ngcontrolsobwarefromSMA
• Func$onaltest• Installingop$calguidescopeandpoin$ngtest(~2arcsecrmserrors)
ZoombandmodeinDiFX
• Correla$onofdatatakenindifferentsamplingscheme(e.g.ALMA62.5MHzvs64MHz)
• ZoombandmodeinDiFXgivesasolu$on:adjustfrequencycoveragetocorrelate
Zoombandcorrela$onexample
Zoombandmodetes$ng
• Wehaveevaluatedcorrela$onwithZoombandmodeusingsimulateddata(NicolasPradel[AUT],H.N)
• Relatedac$vi$esinDiFXgroupinASIAA:– Automa$czoomfrequencyselec$onprogram[NicolasPradel(AUT),ZhengMeyar-Zhao]
– Simulators‘enoise’(expanded‘anoise’fromGeoffCrew)and‘Datasim’development[Cheng-YuKuo,ZhengMeyar-Zhao]
Zoombandtes$ng:methodtotest
• Performseveralrealiza$onsofsimula$onincludingALMA(62.5MHzchannel)andVLBI(32or64MHzchannel)sta$ons.
• Correlatedatawithzoomband(ALMA-VLBI)andwithoutzoomband(VLBI-VLBI),andderivefundamentalquan$$es(amplitudes,phase,closurephase,delay,rate)
• Comparetheresultsfromthecorrela$onbetweenwithandwithoutzoomband.
Zoombandtes$ngsimula$onsetup(oneexample)
• ALMA-CARMA-SMAvsAPEX-CARMA-SMA• ALMA:62.5MHzx32IFchannels• Others:64MHzx32IFchannles• Correla$onzooming32MHzforALMA-CARMA-SMA
• Correla$onwithoutzoomingforAPEX-CARMA-SMA
• Scanfor4spoin$ngtoM87• Sta$s$csweretakenover32IFchannels• AnalysishasbeendonewithAIPS
Correla$onamplitude
Correla$onamplitude
Delayandrate
Delayandrate
Closurephase
Summary
• Wehavemade4ssimula$onswithandwithoutALMAsta$on(62.5MHzchannel).
• Wehaveperformedsta$s$caltests(K-Stest)tocomparecorrela$onswithandwithoutzoombandmode.
• Nosta$s$callysignificantdifferenceswerefoundincorrela$onresults.