Pointing Models for

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Pointing Models for 26 West and East
Anna Castelaz Summer 2003
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Introduction

• Why do we need pointing models?
• Which models did I develop?
• East, 1420 MHz
• East, 4.8 GHz
• West, 4.8 GHz
• Revisions on 1420 MHz for West

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Procedure

• To make a model, I would first have to point the
  telescope at point sources throughout the sky.

SAMPLE POINT 00225544
date object z dist start X start Y peak X peak Y Epoch catalog RA catalog DEC peaked RA peaked DEC Hour Angle
6/13/03 04332933 43.26 42.855 5.209 41.08 5.155 1950 04 33 55.6 29 33 49 04 39 02.7 30 24 44 -03 16 31.6

• There were several calculations necessary to make
  the data easier to work with. I precessed the
  coordinates to the current catalog positions,
  using the site http//fuse.pha.jhu.edu/support/too
  ls/precess.html to do so.
• Then these coordinates and the peaked
  coordinates, in RA and DEC, were changed into
  decimal notation.

SAMPLE POINT
2003.5 RA 2003.5 DEC 2003.5 RA 2003.5 DEC peak RA peak DEC HA
04 37 18 29 40 14.9 4.62167 29.67081 4.65075 30.41222 -3.27544
4

• The coordinates had to be changed into degrees

• The formulae on the left changed the data into
  unit vectors and the ones on the right compensate
  for latitude

• the latittute at PARI is 35.2049 degrees, or
  .6144 radians.

• After taking latitude into account, I could
  finish converting into degrees

SAMPLE POINT
2003.5x 2003.5y 2003.5z 2003.5 X1 2003.5 Z1 2 003.5 SMAJ 2003.5 SMIN
0.56853 -0.65706 0.49502 0.74992 0.61310 41.22418 31.58797
peakx peaky peakz peakX1 peakZ1 peak TMAJ peak TMIN
0.56429 -0.65216 0.50622 0.75291 0.61711 40.89875 31.77976
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• Now I could calculate errors.
• The EMAJ and EMIN errors and the total error

EMAJ EMIN ETOT
-0.32543 0.19179 0.37774
SAMPLE POINT

• I collected approximately 35 points for the
  models for 26 East at 1420 MHz and 26 West at 4.8
  GHz.. There were 51 points from the model for
  West in 1420 last year, and I was only able to
  collect 15 points for East at 4.8. I ran all of
  the points through the calculations.

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Results

• For each model there were four graphs. They were
  combinations of either the observed positions and
  the difference between the catalog and observed
  positions or TMAJ vs. EMAJ, TMAJ vs. EMIN, TMIN
  vs. EMAJ, and TMIN vs. EMIN.
• To save space, I have plotted all four on the
  same graph for each model

Graph for 1420 MHz on 26 East
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Graph for 4.8 GHz on 26 West
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Graph for east 4.8 on this page!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!
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Graph for 1420 MHz on 26 West
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• These graphs are important because their slopes
  and curvatures are used as constants in the
  pointing model formulas.

EMIN vs. TMAJ Curve ME elevation misalignment
in arc sec Slope MA azimuth misalignment in
arc sec
EMIN vs. TMIN Curve TFLX tube flexure for
minor axis Slope SCLMIN minor scale factor

• EMAJ vs. TMAJ
• Curve TFLX tube flexure for major axis
• Slope SCLMIN major scale factor

EMAJ vs. TMIN Curve CH collimation Slope
NP non- perpendicularity
Constants not previously mentioned MAJECC
eccentricity error amplitude MINOFF
eccentricity offset
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The Pointing Model Program

• To run my data in the pointing model program, I
  created a .pat file of the data. This was
  essentially a long column of entries including
  the current catalog RA and DEC, the observed RA
  and DEC, and the HA.
• The program shows graphs and a list of the
  constants. It corrects its pointing by looping
  through the EMIN and EMAJ equations and the
  MajorEorror and MInorError equations. (For the
  EMIN and EMAJ equations, it uses
• and

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