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Commissioning the VST: a new survey machine at ESO

Commissioning the VST: a new survey machine at ESO. P. Schipani 1 , M. Capaccioli 2 , C. Arcidiacono 3 , J. Argomedo 3 , M. Dall’Ora 1 , S. D’Orsi 1 , J. Farinato 4 , D. Magrin 4 , L. Marty 1 , R. Ragazzoni 4 , G. Umbriaco 5

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Commissioning the VST: a new survey machine at ESO

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  1. Commissioning the VST: a new survey machine at ESO P. Schipani1, M. Capaccioli2, C. Arcidiacono3, J. Argomedo3, M. Dall’Ora1, S. D’Orsi1, J. Farinato4, D. Magrin4, L. Marty1, R. Ragazzoni4, G. Umbriaco5 1INAF - OACN, 2University Federico II of Naples, 3INAF-Arcetri, 4INAF-OAPD, 5University of Padua

  2. Telescopes @Paranal: 4 UTs + 4 ATs (ESO) + SurveyTelescopesVISTA (UK) + VST (IT)

  3. The VST project • Joint venture (1998) between ESO and OAC (Osservatorio Astronomico Capodimonte) => INAF • OAC provides the telescope, ESO provides the enclosure and operates the telescope for T≥10 years • OmegaCAMconsortium (Netherlands, Germany, Italy, ESO) provides the OmegaCAM camera

  4. A big challenge for Italy • VST is the first ground-basedactiveopticstelescopedesignedfrom scratch by Italianresearchinstitutes, notbased on replicas of othertelescopes. For the Italian community manythingswerenovelties. • The customeris ESO, the leader organization to buildground-basedtelescopes. A new telescope in Paranalisexpected to work aswellas the existingones(sellingwatches to Rolex?). • VST is the largest INAF project for ESO, alltime • Very small engineering staff compared to similarprojects

  5. VST in brief • Primarymirror: 2.6m • Secondarymirror: 0.9m • F# 5.5 • Field corrector with 3 lenses (2 in the telescope + 1 in the camera) • Field: 1° x 1° • Shack-Hartmannwavefrontsensor • Active M1 shape control (81 activeaxialsupport + 3 axialfixedpoints) • Active M2 positioning in 5 dof (hexapod) • Autoguiding with probe in polarcoordinates • ADC with counter-rotatingdoublet of prisms, exchangeable with 2 Lens corrector

  6. VST in brief • Alt-azmount, 4 motors per axis with glassencoders • ESO standard hardware whereverpossible • 1 TCS Workstation + 8 LCUsbased on VxWorks • 10 electricalcabinets • 60 TCS swmodules • MANY control loops! Alreadytotallyinstalled in 2006, butafter 2007 CDR, deepmodifications to the activeopticssystem design and parts: • primarymirrorsupportsystem • secondarymirrorsupportsystem • probe, ADC, rotator whatwehavenowisVST 2.0

  7. OmegaCAM 268 Mpixel 1°x1° 0.21 arcsec/pixel • 32 scientificCCDs + 4 outerCCDs • Autoguiding • Image analysis curvature sensor PI: K. Kuijken OmegaCAMConsortium: Netherlands, Germany, Italy, ESO

  8. Integration phases 2007-2008: Tel. Mount 2009: M2 system Break caused by disaster in shipping 2010: M1 cell + AU 2011: OmegaCAM

  9. Commissioning 2011 • Looking back • 6 monthsforeseen for the commissioningsof bothtelescope and camera with alternatingperiods • Respected, but for an additionalshiftpostponed to July(shimming of rotator)

  10. Commissioning team Small. ~5 FTE (most of the peoplepart-time available and relatively new to the project) Laurent Marty (Napoli) Sergio D’Orsi (Napoli) PietroSchipani (Napoli) VST-C Project Manager Massimo Dall’Ora (Napoli) Jacopo Farinato (Padova) Gabriele Umbriaco (Padova) Roberto Ragazzoni (Padova) Demetrio Magrin (Padova) Carmelo Arcidiacono (Padova-Arcetri-Bologna) Javier Argomedo (ESO-Arcetri)

  11. Small team, but strong

  12. Commissioningactivities Trackingsystem • Pointing • Tracking • Autoguiding Alignment Active Optics • Primarymirrorsystem • Secondarymirrorsystem • Shack-Hartmann Probe ADC Interfaces with camera (sw, electromechanics)

  13. PointingModel Pointingerror ~1 arcsec RMS Fitresultstypicallybetween 0.8 and 1.1 arcsec A model with 40 starsisbuilt in lessthan 1 hour

  14. TrackingMap in a windy night

  15. TrackingMap With propersetting of the enclosure the telescope performance isunaffectedalso in windynights

  16. Autoguidingoperational TCCD Probe system PII controller

  17. Autoguiding • Tracking performance asmeasured on the guide probe is ≤ 0.1 arcsec RMS (withinspec)

  18. ActiveOptics M1 system M2 system Shack-Hartmann Software Conversion between CCD angles to M1 & M2 systemangles

  19. Active Optics • M1 supportsystemnotastatic: trefoil to be controlled and removed (notsurprisingly) • Aberrationsdiscovered inside the Shack-Hartmannsystem (non common path)

  20. ActiveOptics Active opticsconvergesnormally with: 1 open loopcorrection + 1-2 closedloopcorrections

  21. Alignment Optical system to be aligned: M1+M2+lenses+camera • M1 vs M2 Alignmentcorrected in Februaryrotating M2 aroundits coma-free point (off-axisastigmatismremoved) • Camera tilt removed (by OmegaCAMconsortium) by shims (notrotatingdefocusremoved) • Rotator axis tilt removed by shims, notenoughrange with mirrors (rotatingdefocusremoved) Unexpectedadditional work-shift

  22. Technical problems! Active optics • Shack-Hartmannsystemaberrations (February) Alignment • Tilt of the camera (smaller, June) • Tilt of the rotator axis (larger, July) Cabling • cablesbroken on systemsnottestedenough in Italy (lessonlearned: shipping in advance… means time lost)

  23. Work-sharing… (Different) responsiblesneededatsubsystemlevel

  24. …overcome with: • Strong team spiritwithin the commissioning team. Allpeopleavailable to help in areasnot under theirownresponsibility. Greatpeople. • Verygoodcollaboration with ESO and OmegaCAMteams • Support from ESO Paranal and Garching • Accurate and realisticpreparation of the commissioning. Fewsurprisesand schedule basicallyrespected.

  25. Image quality • Wide-fieldtelescope more complicatedthan «normal» ones. Normallynegligiblealignmentproblemsare herevisibleon the outeredge of the field. • (plan HUGE alignmentcorrectioncapabilities!) • Image qualityhas to be assessed over the wholefield: • PSF Anisotropy • FWHM map • Ellipticitymap

  26. PSF Anisotropybeforeshimming Degradationon one side / corner

  27. After the shimming

  28. FWHM map

  29. Ellipticity map

  30. Planned surveys ESO Public surveys: • KIDS (Kilo-DegreeSurvey) • ATLAS (Sky Atlas with VST) • VPHAS+ (VST Photometric H-aSurvey of the Southern GalacticPlane) GTO basedsurveys: • Strega, Step, Access, Vegas, Voice, Sudare, U-Wings, Local Group, …

  31. GTO agreement • MOU: 1998 • Finalagreement: 15/06/2011 VST GTO returns: 10% for years 1-2-3-4, 15% for years 5-6, 20% for years 7-8-9-10

  32. Start of operations • Official start of operationsisOctober, 1 • Dry runs • Science data taken in sharedrisk SURVEY DATA COMING SOON

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