Figuring out the wedge position on the rotary floor
Lynn baker and mike nolan hung a target
the alfa location and surveyed its position in dome center line
Mike and I did a survey to start locating the ALFA system on
mounted a single target thru two exisitng holes in the
was horizontally centered between the two holes in the plane of
and extended 22 3/16" below the top surface of the floor.
3/4" thick and this is included in the 22 3/16" measurement.
that the extension was perpendicular to the bottom plane of the
within perhaps a 1/4" or so. We then measured the location
target using the usual technique of surveying a reference set on
secondary and back fitting a coordinate system in the survey
The reference set used is dome centerline coordinates and units of
We moved the turret position until the y coordinate of the
close to zero. The turret angle was 26.5
coordinates of the
For reference, the focal point of the optics in the same
Nominal focus: -248.145
The target was not too far from the nominal focus.
approximation that the floor is in the x-y plane of the dome
with the z axis upward and perpendicular to the floor. (Not
small motions). Moving along the floor 1.5" radially
original bolt holes, (away from the secondary) places a
focal point. The focal point would be 18.3 inches
of the floor at this new point.
The reference is now the two holes that straddle the center of the
pie region. Using:
I get that
8.17 degrees for the tilt angle of the horn
18.3 inches focus below the top of the floor (measured by lynn
1.5 inches radially in to go from reference to focus
24.4094 inches alfa focus to where alfa attaches to the wedge
4.5 inches as the vertical height of the wedge at it's center
1.063 inches radially inward as german corte's offset (in the
the center of the wedge should be 5.82 inches radially
the holes on the floor.
We need a shim of 1.22 inches between alfa and the
how i arrived at the numbers.
There is an error in the plot (found by felix..)
- B=18.3*sin(8.17)=2.6".. should be
- B=18.3*tan(8.17)=2.63" .. so there is an error of