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I-VLBI Applications Salvo Pluchino, INAF-IRA Noto VLBI Station Mini Workshop casper backends

I-VLBI Applications Salvo Pluchino, INAF-IRA Noto VLBI Station Mini Workshop casper backends. Italian VLBI network: le strutture. In Italia attualmente vi sono 3 antenne (saranno 4 con SRT) equipaggiate per le osservazioni VLBI. Mc.

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I-VLBI Applications Salvo Pluchino, INAF-IRA Noto VLBI Station Mini Workshop casper backends

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  1. I-VLBI Applications Salvo Pluchino, INAF-IRA Noto VLBI StationMini Workshopcasperbackends

  2. Italian VLBI network: le strutture In Italia attualmente vi sono 3 antenne (saranno 4 con SRT) equipaggiate per le osservazioni VLBI. Mc La rete I-VLBI ha una risoluzione che supera ad esempio quella di MERLIN (JodrellBank, con baselines fino a 217 km) ed offre diversi scenari di utilizzo. 592 km 894 km Ma 581 km SRT Nt Posizione delle antenne VLBI italiane in coordinate cartesiane, latitudine, longitudine ed altezza s.l.m. (Posizione SRT appros.). Mini Workshop Casper Backends - Medicina 8 April 2011

  3. Italian VLBI network: copertura UV Funzionedivisibilitàsul piano UV per le 3 antenne INAF Italiane, per sorgenti a −30, 0, 30, 45 e 90° dideclinazione. Mini Workshop Casper Backends - Medicina 8 April 2011

  4. Italian VLBI network: quando preferirlo? • Progetti che non richiedono l’uso di grandi array • Progetti che non possono essere studiati con altri array (ad es. per il frequencycoverage) • A differenza di altre network VLBI (estese in direzione E-W), l’I-VLBI è più esteso in direzione N-S, questo rende possibile finestre osservative più lunghe per oggetti a basse declinazioni • Inoltre le antenne italiane riescono ancora ad osservare agevolmente le sorgenti circum polari … per contro: • La debolezza maggiore del network I-VLBI è di avere baselines di lunghezza comparabile(soltanto una piccola parte delle frequenze spaziali può essere campionata) • Il piccolo numero di stazioni rende più difficoltosa la ricostruzione di una sorgente Mini Workshop Casper Backends - Medicina 8 April 2011

  5. Italian VLBI network: quali applicazioni? • Osservazioni in SpectralLine • Astrometria di Masers (CH3OH, H2O) • Survey di Megamasers (H2O) • Planetologia • Tracking di Spacecraft • SpaceDebris • SETI in piggyback • Altro? • Osservazioni nel Continuo • ? Mini Workshop Casper Backends - Medicina 8 April 2011

  6. Precedentiesperienze: VEX I-VLBI tracking doppler IRA Bologna Medicina INAF Rome SRT Cagliari IRA-Noto On Dec 1st 2008 a Venus lunar occultation occurred. On that occasion we performed the first Italian-VLBI (I-VLBI) tracking experiment by detecting the carrier signals coming from the Venus Express (VEX) spacecraft with both the IRA radiotelescopes together with the Matera antenna of the Italian Space Agency. BASELINE LENGTHS (km) Mc Ma NtMc0 597 893Ma597 0 444Nt893 444 0RECORDING SYSTEM Station Drive type DAR MEDICINA MARK5A MKIV MATERA MARK5A MKIV NOTO MARK5A VLBA4 Medicina, INAF-IRA 25 m Noto, INAF-IRA 32 m Matera, ASI 20 m

  7. Data post processing required the development of new dedicated software and firmware. Precedentiesperienze: VEX I-VLBI tracking doppler DifX correlator at IRA

  8. Preliminary results: Precedentiesperienze: VEX I-VLBI tracking doppler Post processing: FFT @ 320000 ch (full spectrum)Averaging: 1 sRes [Hz/ch]: 25Res [el/cm2]: 1.6*1014 el/cm2 On the left: diffraction patterns of immersion and emersion of the X-band carrier.iBob-BEE2 acquisition system. TEC variation during the emersion. Note: Delta reaches 1013 el/cm2, i.e.  30 TECU (1 TECU=1016 el/m2). Below: Total Electron Content (TEC) variation during immersion of VEX behind the Moon limb. iBob-BEE2 acquisition system. Above: Total Power hi-resolution spectrum (4Mch, 2Hz/ch) of the X-band carrier. Mk5 acquisistion system at MC.

  9. Italian VLBI network: downconversion e sampling 14 VIDEOCONVERTER BW: 0.125  16 MHz Terminale Mark IV/VLBA 100 – 220(L) 100 – 900 (L) ATTENUATORI 100 – 500 100 – 500 220 – 500(L) (Es. BW=800 MHz) SECONDA CONVERSIONE 14 VC 100 – 220(R) 100 – 900 (R) 220 – 500(R) 28 channels (L + R) Terminale Mark V Modulo A Modulo B 1 Gbit/s A/D CONVERTER (1-2 bit) Hard Disk Hard Disk CORRELATOR (DifX, JIVE) Mini Workshop Casper Backends - Medicina 8 April 2011

  10. Italian VLBI network: downconversion e sampling – A “ROACH” approach Terminale Mark IV/VLBA ROACH Board 4 inputs @ BW = 250 MHz 100 – 220(L) 100 – 900 (L) ATTENUATORI 100 – 500 100 – 500 220 – 500(L) (Es. BW=800 MHz) 100 – 220(R) 100 – 900 (R) 220 – 500(R) A/D CONVERTER (8 bit) Time domain  COMPLEX FFT n-HIGH RESOLUTION FFT n TunableDownconversions G Lan n-SPECTRA n-COMPLEX FFT  nTime domain streams n-SIGNALS Host PC HIGH RESOLUTION SOFTWARE CORRELATOR Mini Workshop Casper Backends - Medicina 8 April 2011

  11. Italian VLBI network: Spectra Software Correlator DATABASE Geocentriccorrection and Band Filtering Mc Nt SRT Geocorrected and Station Averageddata Final Spectrum Frequency Multiplication of Spectra Spectra with residual RFI Mini Workshop Casper Backends - Medicina 8 April 2011

  12. Italian VLBI network: High Resolution Software Correlator DELAY TABLE (precalculated) PHASE CORRECTION MODEL DATABASE Mc Nt Geocentriccorrection and Narrow Band Filtering Makenew PHASE TABLE SRT Geocorrected and filtered data Detection of the signal Global AveragedSpectra Mini Workshop Casper Backends - Medicina 8 April 2011

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