•  What was done
• 21may18 looking around
  
• 22may18 placing targets on rim wall, visitor center balcony observation
  
• 23may18 road between anchor 4 and gate to river
• 24may18 ao9 and visitor center 
  
• Some pictures of the scanner locations
  
• Numeric values needed for calibration
• Measuring the location of the rim wall targets with the leica theodolite
  

4Ghz scan from AO9

Lining up aberration features with features on the dish

• scanner orientation (.png)
  
• rotate to north, include main cables (.png)
  
• Each vertical red line is a main cable (spaced every 25 feet)
  
• A number of the points are centered on a main north,south cable.
• processing: x101/blackmore/aberration.pro
• Photos taken of the dish 16jun18 from rim road, ao9.
  

Blackmore presentations/reports:

• These presentations/reports may contain proprietary info from Blackmore.
• Access is limited to the internal AO network.
• Blackmore presentation introducing their technique (.pdf)
• Blackmore summary report of the survey (.pdf) 17MB
• This includes photos taken during the survey, images constructed from the scanner, and their conclusions.
• blackmore jul18 update (.pdf)
  

• placing a target on each panel (38000+ panels).
• to redo a photogrammetry survey we would probably first have to remove the old degraded targets
• Take 30 to 50 9" photographs from each tower,
• each photograph had about 18000 targets on it.
• the locations of the targets on each photo was measured on an optical measuring machine (to a few micron accuracy).
  
• This took about 6 months.
• A blackmore scan from say ao9 would take about 1 hour... no need to put targets on the dish.

    The unknown is whether the blackmore scanner could reach the required resolution. After the last photogrammetry survey/adjustment/survey, the rms surface error was measured to be about 2.2 mm. So we would ideally like sub mm resolution.
 

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The May18 survey

     Blackmore sensors surveyed  the primary reflector and telescope with their FMCW lidar scanner 22-24 may18

What was done:

21may18:

• 4 possible locations were inspected:
  
• visitor center balcony
• upper road between anchor 4 and gate to rio tanama (by tony's old camera stand)
• midway up the road between the base of tower 8 and the turn to go to  anchor 8.
• AO9.
• Maintenance cleared brush in front of the anchor 4 road, and the base of tower 8 road.

22may18 - visitor center balcony measurements

• reflective targets (leica (L) square targets, and round (R) targets that had been used for the photogrammetry survey) were placed around the rim wall
• the targets were placed on the cement blocks near the main cables (the targets were not on the main cables).
• at each spot 2 targets were placed .. (one about 12 -18 inches above the other). We eventually ran out of the (L) targets. When both types were used, the leica (L) target was always the upper target.
  
• the locations were:
• NW 02 (L,R)
• NE 02  (L,R)
• NE 05 (L,R)
• SE 02 (R,R)
• SE 05 (L,R)
• SW 02 (X,X)
• NW 05 (L,R)
• These were going to be used to tie the blackmore measurements to AO9.
• The blackmore lidar would see the targets
• We would also measure the targets from A09 using the sokia theodolite.
• Unfortunately, the sokia could not see the targets at the rim wall from AO9.
• We ended up mounting the blackmore scanner atop AO9 (see 24may18)
•  the below as pictures of the dish locations, and the target positioning
  
• the round  targets are about 3" across.
  

  location (.jpg)	targets (.jpg)
  NW-02	NW-02
  NE-02	NE-02
  NE-05	NE-05
  SE-05	SE-05
  SE-02	SE-02
  SW-02	SW-02
  SW-05	SW-05
  NW-05	NW-05

  
  
• Measurements from the visitor center balcony.
• data was taken  18:30 to about 22:00.
• the observations were interrupted many time because of rain.
• 1.5 GHz chirp bandwidth was used.
• The data is in the VisitorCenter_Night1 subdirectory.
• the dish, platform, cables, towers were scanned.
• Pictures from the balcony

• evening..rain (.jpg)

  night .. rain .jpg

  looking at the data (.mov 46Mbytes)

  
  

23may18 - road between anchor 4 and gate to river.

• data was taken on the road between anchor 4 and the gate going down to the river.
• The tripod was mounted next to tony acevedo's old camera stand.
• data was taken from 18:00 to around 22:00.. with some breaks for rain,
• the dish, platform (i think), cables, 12meter antenna were all scanned.
• 1.5 GHz chirp was used.
  
• the data is in the FarSide_Night2 subdirectory.
•  pictures from the observing site
•  

  before clearing the brush (.jpg)

  setting up the equipment (.jpg)

  calibrating (.jpg)

  
  

24may18  - AO9 and visitor center.

• scanning from AO9, morning,afternoon
  
• data was taken starting around 10:00 am till around 14:00
• we built a clamping device  to mount their scanner on AO9
• they had a 12"x12" breadboard with mounting holes and a center tap.
• we clamped this to the top of ao9
• a prism mount was used to center the breadboard above ao9
• adjusting screws and levels were then used to level the bread board.
• the top of the breadboard was 1.512" above the top of ao9.
  
• this will be the z offset of their measurements relative to the top of ao9.
• 1.5 GHz chirp bandwidth scan. this started around 10:00 am.
  
• the dish was scanned. This picked up all of the reflector targets we mounted on the rim wall
• 4GHz chirp bandwidth
• this was started after noon.
  
• the data is in the subdirectories: AO9_Day3/ao9_1p5G,ao9_4G
• scanning from visitor center balcony.
• This started around 18:00
• the dish was scanned at 3.5 GHz
  
• This did not make it to the other side of the dish
• The dish was re scanned at 3GHz. this made it all the way across.
• The data is in the subdirectory VisitorCenter_Night3
• See the readme.txt file in that directory.. (to separate out the 3.5 and 3GHz data)
• pictures from the visitor center

• from the balcony at 19:00 (.jpg)

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Some pictures from scanner location looking toward dish

From visitors  center balcony Looking south	left half	right half
from t4 anchor - gate to river road looking north	left half	right half

    The pictures show the parts of the dish that have been cleaned.

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Some numeric values need for registration:

• base of scanner above ao9: 1.512 inches
• Offset of scanner from center of breadboard
• We measured the distance from the base of the scanner to the 4 edges
  
• 
•  the scanner was mounted so that the cable face pointed approximately at the lower right corner of the picture
• the 2.954" offset side was probably NNW direction.
• Telescope location for each day:
  
• we left the telescope at:
• az=270, grza=10, chza=stow  (encoder positions, no model correction)
• The tiedowns were disabled before the start of each run,
  

see also: /share/megs/survey/180521