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.