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 |