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Out-Of-Focus Holography

• Next meeting:
  • September
• Past meetings:
  • Aug 21, 2008
  • Jun 06, 2008 (follow-up emails)
  • Apr 04, 2008
  • Feb 05, 2008
  • Jan 23, 2008
  • Dec 07, 2007

Aims for the 2007/08 season

• Events
  • Informal workshop on OOF Holography -- September 25-28, 2007, Green Bank, WV
• Tasks
  • Initial plans for investigation of OOF Holography with MUSTANG
  • Rewrite baseline removal code for Q-band OOF (completed)
  • Process Dec 2006 and newer Ka-band data (has begun)
  • Streamlining of end-to-end OOF map analysis and actuator adjustments (underway)
• Relevant links
  • Current instructions for use of the OOF software.
  • Mustang observing run notes

• Active Surface Manager MRs:
  • 1C104: GBT M&C Active Surface Zernike Polynomial
  • 1C406: Incorporate OOF Holography Zernike Models into Active Surface
  • 8C304: Revise software procedure that turns active surface power supplies off
  • 8C308: thermal Zernike terms (new in 2008)
  • 1C408: Integrate Holography Scanning Procedure and Data Analysis Code into GBT Software Suite (new in 2008)
  • 4C608: table order and Thrmzern key
  • Active Surface Manager FITS file specification
• Results for 2007/2008 season
  • QbandBeam1LProblems
  • TPAR_18: original processing, followup processing, log, other notes (Jan 08, 2008)
  • TPAR_18: Comparison between Q-band and Mustang
  • MUSTANG science run 8 OOF (March 12-13, 2008)
  • March 24, 2008 test of new actuator zero file (with central row problem fixed)

Earlier seasons

2006/2007 season

• Discussion on Nov 21, 2006
  • Rick's presentation (Note: the year 07 in the filename is in error)
  • Bruce's presentation
  • Richard's presentation (from 18 August 2006 CDL talk)

Aims and Results from the 2005/06 season

• Implement an empirical active surface correction, integrated as far as possible into observing scripts, for observations with the Q- and possibly Ka-band receivers. Initially use already derived models.

• Using all of the high quality data from the 2005 Spring season, re-derive a model from surface deformation due to gravity.

• Investigate the connection between thermally induced displacements of the sub-reflector and astigmatism-like aberrations. Produce experimental observe-time corrections for this using the observed pointing shifts. See Project note 50 and the Summary of Daytime OOF page

• Make OOF observations and reduction routine.

• OOF with the Penn Array.

Long-term aims

• Investigate sparse mapping techniques producing very low resolution aperture maps.

Results from Fall 2005 campaign

• An illustration of OOF Repeatability OOFRepeatability.

Status and development of OOF software:

Astronomy and Astrophysics papers describing the technique, and application to the GBT:

• OOF Paper 1: B. Nikolic, R. E. Hills, and J. S. Richer. "Measurement of antenna surfaces from in- and out-of-focus beam maps using astronomical sources" A&A 465, 679–683 (2007) ADS Link
• OOF Paper 2: Nikolic, B.; Prestage, R. M.; Balser, D. S.; Chandler, C. J.; Hills, R. E. "Out-of-focus holography at the Green Bank Telescope" A&A 465, 685-693 (2007) ADS Link

Wiki Pages on the OOF technique and details

• Numbering conventions for Zernike polynomials are discussed in OOFHolographyZernikePolys
• The `natural' coordinate system for OOF holography is discussed in OOFCoordsys
• Calculating the accuracy of maps derived from OOF measurements is discussed in OOFFormalErrors.
• The phase change due to sub-reflector movement is discussed here OOFSubPhase.
• Documentation on the format of data input to the OOF software OOFInputFormat.
• OOFOutputs describes the outputs of the OOF software

Summary of OOF data for Winter 2004/2005

• OOFSummarySpring2005
• OOFResults2005
• OOFResults20050410
• OOFResults20050411
• OOFInfocusBeamAnalysisSpring2005
• OOFGBTAstigmatism discusses some OOF measurements of astigmatism.

Summary of OOF data for Winter 2005/20066

• OOFSummaryFall2005

Notes on previous observations

Past Tests

Ka-band data reduction and analysis

See OOFKaStrategySpring2005 for observing strategy. See OOFKaReductionSpring2005 for data reduction. See OOFKaAnalysisSpring2005 for data analysis.

Some pointers to relevant older data

See OOFMapsSpring2004

Figuring out the signs and coordinate systems

• 2003
  • Observations are described here.
  • A good bump "on" data set is: /home/groups/ptcs/analysis/oof/old/apr2003/amp_pha/apr21/scan1606L.fits
  • Scan 1667 is without the bump. Both of these are spectral line at 12 GHz.
  • The bump files created for this test appear to be here (they are modified zero point files):
    • /home/groups/ptcs/obs/setup/asBump22GHz.txt (255 actuator zero points have been bumped by 1690um) (Matlab plot, Matlab image)
    • /home/groups/ptcs/obs/setup/asBump12GHz.txt (255 actuator zero points have been bumped by 2950um)
  • According to the email from Don Wells who created this bump file, the bump is: away and to the right when looking from feed arm. This corresponds to the bottom [right] quadrant within the OOF software. (Note: Todd added the word [right].)
• 2004
  • The bump definition used in TPTCSDSB040225 is from Richard Hills and generated by Zernikes. It appears to be an attempt to match the zero point file bump.
  • /home/groups/ptcs/surfmodels/RHBump/surfacepars-el60.fits (Matlab plot)
  • /home/groups/ptcs/surfmodels/RHBumpHalf/surfacepars-el60.fits (Matlab plot)
  • This bump file can be further scaled by this script, which was used to create /home/groups/ptcs/surfmodels/RHBumpDouble/surfacepars-el60.fits with a 3.8mm peak (76 deg phase at 3.6cm) (Matlab plot)

-- BojanNikolic - 12 Jan 2005

• ptcs/surfmodels/RHBumpDouble/surfacepars-el60.fits:
  

Attachment:	Action:	Size:	Date:	Who:	Comment:
bump_reh.png	action	69718	30 Apr 2008 - 22:23	ToddHunter	ptcs/surfmodels/RHBump/surfacepars-el60.fits plot
bump_reh_half.png	action	69655	30 Apr 2008 - 22:24	ToddHunter	ptcs/surfmodels/RHBumpHalf/surfacepars-el60.fits
bump_reh.m	action	1991	30 Apr 2008 - 22:43	ToddHunter	Matlab script that generated bump_reh.png
bump_reh_half.m	action	1850	30 Apr 2008 - 22:43	ToddHunter	Matlab script that generated bump_reh_half.png
don.email	action	2377	01 May 2008 - 14:13	ToddHunter	2003apr17 email from Don Wells
asBump22GHz.png	action	34347	01 May 2008 - 14:22	ToddHunter	matlab plot of asBump22GHz.txt
asOrthogonalDistance.c	action	3173	01 May 2008 - 14:40	ToddHunter	attachment to Don's 2003apr17 email
asBump22GHzImage.png	action	35669	01 May 2008 - 18:53	ToddHunter	image version of bump file
plotAsBump22GHz.m	action	2290	01 May 2008 - 18:56	ToddHunter	Matlab script that generated the above image
scalebump.py	action	753	08 May 2008 - 15:26	ToddHunter	script to scale the Zernike bump by some factor
bump_reh_double.png	action	70459	08 May 2008 - 15:56	ToddHunter	ptcs/surfmodels/RHBumpDouble/surfacepars-el60.fits
oofreport_hills.pdf	action	5756463	10 Jun 2008 - 21:31	ToddHunter	Fundamentals of OOF by Richard Hills (21 pages)
GBT_11.20.07_rick.pdf	action	781420	10 Jun 2008 - 21:36	ToddHunter	Rick Lyon's November 2006 slides
2006_11_20_WFS_Intro_bruce.pdf	action	2082390	10 Jun 2008 - 21:37	ToddHunter	Bruce Dean's November 2006 slides
SurfaceSubset_richard.pdf	action	3213707	10 Jun 2008 - 21:38	ToddHunter	Richard Prestage's November 2006 slides