The Pointing Performance
 of the ALMA Prototype Antennas
Jeff Mangum (NRAO)     Patrick Wallace (RAL)
Robert Lucas (IRAM)

The AEG
Jeff Mangum (NRAO)
Jaap Baars (ESO/MPIfR)
Albert Greve (IRAM)
Robert Lucas (IRAM)
Ralph Snel (Lund University)
Pat Wallace (RAL)

The ATF
Major Antenna Performance Specifications
Pointing
Techniques and Systems Used:
Optical Pointing Telescope (OPT)
1 and 3 mm Radiometry
Accelerometer System

Optical Pointing Telescope
NRAO Design
4-inch Refractor
IR (l > 700nm) and clear focus correction filters
Rolled-Invar Tube
COTS CCD/Frame Grabber
EPS = 1.1 arcsec per pixel
FOV = 12x9 arcmin
Sensitivity > 7th mag in 5 second exposure

Optical Pointing Telescope (cont.)
Evaluation Frontend System
Radiometric Measurements of Mercury
VertexRSI (left)
qMercury = 5.1 arcsec
265 GHz
Solar Separation 16¡

Accelerometer System
10 Endevco Model 86 Seismic Accelerometers
2/3 Axis Configuration
Sensitivity over 0.1 to 30 Hz (10 to 0.03 sec) with accuracy several mm to 10 nm
Extended to 0.001 Hz (15 minutes) using wind power spectrum extrapolation
Coupled with Sonic Anemometer Measurements

Positioning Calculation
Basic Pointing Model
Basic Pointing Model Fits
Pointing Model Fit Procedure
Tripod Print-Through on the VertexRSI Antenna
Optical Pointing Measurements
All-Sky Optical Pointing Results
ALMA Core Pointing Model
Accelerometer Measurements of Offset Pointing
4 BUS rim accelerometers used to derive BUS pointing
Red: SOW wind, Green: Chajnantor wind, Blue: antenna wake turbulence

Accelerometer Measurements of BUS Pointing Errors
Accelerometer Measurements of BUS Pointing Errors (cont.)
Pointing Performance Summary
ALMA Prototype Antenna Performance Summary
The ATF Backbone
Christian Holmstedt (NRAO)
Andrea Vaccari (NRAO)
Greg Chavez (NRAO)
Mike LeBlanc (NRAO)
Jon Spargo (NRAO)
Brian Glendenning (NRAO)
Ralph Marson (NRAO)
Ken Ramey (NRAO)
Mark Holdaway (NRAO)
Pepe Lopez-Perez (OAN)
Angel Otarola (ESO)
Patty Lindsey (NRAO)
Jinquan Cheng (NRAO)
Marc Rafal (NRAO)
VLA Mechanical Shop
Nicholas Emerson
Robert Lucas
Jack Meadows
Fritz Stauffer

Nicholas Emerson
Robert Lucas
Jack Meadows
Fritz Stauffer