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LBC-Blue pre-commissioning

LBC-Blue pre-commissioning. LBC-Blue E Giallongo (PI) Rome: diPaola, Pedichini, Speziali, Testa, Gallozzi Arcetri/Padova/Bologna: Ragazzoni (co-PI), Barufollo, Diolaiti Trieste: Smareglia, Gasparo field of view, filters taking data: preparing & executing the observations

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LBC-Blue pre-commissioning

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  1. LBC-Blue pre-commissioning • LBC-Blue • E Giallongo (PI) • Rome: diPaola, Pedichini, Speziali, Testa, Gallozzi • Arcetri/Padova/Bologna: Ragazzoni (co-PI), Barufollo, Diolaiti • Trieste: Smareglia, Gasparo • field of view, filters • taking data: preparing & executing the observations • Two pre-commissioning runs this year: • Summer (May – mid-July) • Fall (mid-Sept to present) leading up to LBC-Blue commissioning late October

  2. Opto-mechanical Design

  3. LBC-Blue: focal plane • 4 2048 x 4608 pix ‘science’ chips • 0.23”/pxl (7.85’ x 17.7’ per chip) • separated by 80 pxl (18”) gaps • ~ 27’ x 27’ field of view • 2 512 x 2048 pix ‘technical’ chips • first 256 lines masked to be used without shutter (~frame transfer CCDs) • fast readout: 1.2s for the 256x2048 area • 1’ x 7.85’ field of view • for guiding & active optics • all behind shutter & filter from “LBC Blue Channel: The CCD Camera” (Giallongo (PI), Speziali, diPaola, Pedichini , Ragazzoni (co-PI)& LBC team)

  4. Wavelength coverage • Filters intended (8/channel at one time) • LBC-Blue: • Bessel U,B,V • Sloan g’, r’ (u’ to be added) • LBC-Red: • Bessel V, R, mod-I • Sloan r’,z’ (i’ to be added) • NB 910nm/30nm fwhm (under consideration) • Sensitivities • ETC gives 5s-1hr for 0.9” seeing, 1.8” SW aperture, no moon, airmass = 1.3: • B~27.1, U~25.4, V~26.9 • First light image at B consistent with estimate from ETC. • Estimates only! to be measured during commissioning…

  5. Preparing Observing Blocks • OB tool runs on Linux & Windows (Gallozzi) • set pointing, position angle • configure Blue & Red channel: dither pattern, exposure time, Nexp • Writes out xml file

  6. Executing Observing Blocks • LBC Control SW: • Runs from firefox browser • Uploads OB • Executes observation • Interfaces with TCS: slews, obtains rotator trajectory, dithers • Guiding for exposures longer than a given threshold (~30sec) • Technical chip exposures 2,4,8,…sec taken • Automatically searched for stars; when sufficient stars found, starts guiding

  7. Focus & Collimation • Slew to target • Execute OB to move M1 down by 0.8mm (60pxl pupil) • Obtain 15-20s image using a ~1000 line window of chip 2 • Analyze with IDL algorithm (Barufollo & Ragazzoni): • Automatically finds bright isolated pupils • computes Zernike coefficients • sends the results to the TCS/PSF which adjusts mirror position & forces • 2-3 iterations to achieve focus & collimation • Frequency of focus/collimation? TBD, depends on accuracy of collimation lookup table

  8. Summer (May to mid-July) pre-commissioning • CCD Controllers (Pedichini, Skytech) • Returned from Rome/Skytech • Source of pickup noise tracked down and eliminated • Decreased image transfer time (diPaola & Smareglia) • 105s total: • 26 s readout (41 s readout & demultiplexing) • transfer from LBC CMU to archive and from • LBC archive to user machine • Development of single extra-focal image analysis algorithm (Barufollo & Ragazzoni) • MAT (4” rms) and LBC (7.6” rms) pointing models • First collimation lookup table made • Mirror position (x,y,z,rx,ry) vs elevation for about a dozen datapoints. • Outstanding Issues in mid-July: • rotator cable chain buckling • Focal plane tilt (100 microns) which had existed since fall 2005.

  9. Fall (Sept – late Oct) pre-commissioning • New rotator cable chain installed • Fixed focal plane tilt • Shimmed rotator flange by 0.38mm • Guiding works • Tasks for the next two weekends: • Refinement of collimation lookup table • Refinement of pointing models (MAT and LBC) • Refinement of active optics code (Oct 19-22) • LBC-Blue Commissioning to begin October 23

  10. Quantum Efficiencies from Pedichini F., Speziali, R., Diolaiti, E., Ragazzoni, R. 2002, “The Large Binocular Camera of LBT: The focal plane detectors”, http://lbc.mporzio.astro.it/Documentation/The_Detectors.pdf (in later document, one blue chip differs; QE for this one 1-8% lower but similar shape)

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