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Description of various C3 vignetting correction files at NRL:
FITS files are located at $LASCO_DATA/calib. All GIFs are scaled between
0 and 50 with color table Rainbow18 (loadct, 38) applied.
C3clearvig_990812.fts
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GIF
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Derived by Matt Moorman using star brightness and position. The 3 non-pylon
quadrants are a constant, theta-independent radial function. The pylon
quadrant was derived differently, and has a significant discontinuity at
the quadrant boundaries
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Occ_cntr (center of revolution) is 516.3, 529.5.
C3clearvig_001025.fts
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GIF
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Derived by Nathan Rich from stars. Attempts to fit separate exponential
functions to the occulter and edge at discrete angles (theta) described
here.
C3clearvig0.fts
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Original vignetting correction computed by Clarence Korendyke from pre-flight
data (I think).
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GIF
C3clearvig2.fts
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Similar to C3clearvig0.fts with an inverse-r scaling (radial filter)
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GIF
C3clearvig_las.fts
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Vignetting correction from LAS/Antoine Llebaria, c. 2000
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GIF
C3clearvig_mm_nopyl.fts
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C3clearvig_990812.fts with the pylon quadrant removed
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GIF
C3clearvig_nrl.fts ( = C3clearvig_010117.fts)
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The LAS correction with no pylon multiplied by C3pylonvig_010110.fts
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Center is 518.5, 529.5
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GIF
C3clearvig_nrl2.fts
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C3clearvig_nrl.fts truncated at max 50 and with some smoothing applied
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GIF
C3pylonvig_010110.fts
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A pylon vignetting correction derived from a monthly background model image:
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a. find model where football is near horizontal (3m_clcl_970101.fts???)
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b. rotated 3.56 degrees and shifted so occulter center is at 511.5, 511.5
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c flip image about center
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d. replace bottom of a. with bottom of b.
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e. divide d. by a.
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f. do a ROI to pick out pylon and make everthing else 1.0
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g. smooth
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Center is 518.5, 529.5
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GIF
C3clearvig_morrill.fts
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From Jeff Morrill, prior to Sept 2002
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Center is 516.4, 531.15
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GIF
mda_vig.fts
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From Mike Andrews, prior to March 2002
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Same as C3clearvig_990812.fts (M. Moorman) with pylon quadrant scaled to
the adjoining quadrants
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GIF
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