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)