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LBCBlue precommissioning

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Interfaces with TCS: slews, obtains rotator trajectory, dithers ... rotator cable chain buckling. Focal plane tilt (100 microns) which had existed since fall 2005. ... – PowerPoint PPT presentation

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Title: LBCBlue precommissioning


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
  • B27.1, U25.4, V26.9
  • 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_Dete
ctors.pdf (in later document, one blue chip
differs QE for this one 1-8 lower but similar
shape)
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