J. D. Cline 1, M. W. Castelaz 1, A. Castelaz 2,3 1 PARI; 2 Summer Research Student at PARI; 3 Webb...
1
J. D. Cline 1 , M. W. Castelaz 1 , A. Castelaz 2,3 1 PARI; 2 Summer Research Student at PARI; 3 Webb Institute of Naval Architecture Two 26 Meter Radio Telescopes for Long- Term Monitoring Programs and Surveys Not-for- profit public foundation www.pari.e du The 26 m radio telescopes •Installed by NASA for the Gemini and Apollo programs. •In excellent condition because of rigorous and consistent periodic maintenance since that time. •Motion controls have been upgraded for astronomical use. This poster presents •The new control system •The pointing models •FeedBox infrastructure support •Current research •New research initiative Introducti Introducti on on Current Research Current Research Pointing Pointing Models Models See http://www.pari.edu/ for more information •Each telescope follows an alt-alt coordinate system. •The major axis moves the telescope East-West. •The minor axis moves the telescope North-South. • DFM Engineering telescope control system. • Installed on 26 East antenna in 2001 and 26 West antenna in 2002. Session 49.04 Tuesday, January 11, 2005. AAS 205th Meeting Pulsars •Dr. David Moffett, Furman University, PI. •327 MHz receiver installed on 26 East antenna. •Timings of a dozen pulsars. Methanol Maser Survey •Dr. Mel Blake, PARI, PI. •6.7 GHz receiver installed on 26 West antenna. •Unbiased single-dish survey of northern hemisphere sky. •Currently in the process of receiver calibration. The New Control The New Control System System Majo r Axis Mino r Axis Control of both antenna are linked to a central computer which •Controls the telescopes separately or as a common pair. •Drives a telescope in raster scan mode for mapping. •Allows user-defined catalogs. •Uses either Equatorial or Galactic coordinates. •Define track rates. Telecontrol on the central computer. Features standard telescope control items including: • Equatorial and GalacticCoordin ates • Time • Telescope Pisgah Astronomical Research Institute is a not-for-profit public foundation located on 200 acres in Western North Carolina in the Pisgah National Forest. Two 26 m radio telescopes on a 300 m nearly east-west baseline 26 West Antenna 26 East Antenna New Research New Research Initiative Initiative Extreme Scattering Events (ESEs) and Intra- Day Variables (IDVs). Brian Dennison, UNC-Asheville, PI. •Long-term monitoring of interstellar turbulence via its effect on scattering of radio waves over a large sample of compact sources. •Two element interferometer to reduce noise confusion and measure point sources. •Two frequencies, 2.4 GHz and 8.4 GHz. FeedBox FeedBox Infrastructure Infrastructure Pointing Models Correct for • Non-perpendicularity of radio axis to minor axis • Non-perpendicularity of minor to major axes • Elevation misalignment in both axes • Azimuth misalignment in both axes • Encoder eccentricity and phase angle • Tube flexure in both axes Procedure for Pointing Model • Point the telescope at radio point sources throughout the sky and record observed Major and Minor axis positions. • Difference Observed and Catalog Positions. • Plot differences with catalog positions. • Fit the plots with second order polynomials – coefficients are pointing model parameters EMIN = difference between Minor axis observed and catalog position EMAJ = difference between Major axis observed and catalog position TMIN = Minor Axis Observed Position TMAJ =Major Axis Observed Position TM AJ,EM AJ allpoints y = 0.0069x + 0.011 R 2 = 0.9265 y = 5E -06x 2 + 0.0068x + 0.0066 R 2 = 0.9272 -0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 -100 -50 0 50 100 TM A J obs EM A J error Series1 Linear(S eries1) Poly.(S eries1) TM AJ,EMIN allpoints y = 2E -05x 2 -0.0019x -0.6292 R 2 = 0.1502 -1 -0.8 -0.6 -0.4 -0.2 0 -100 -50 0 50 100 TM A J obs EM IN error Series1 Linear(Series1) Poly.(S eries1) TM IN,EM AJ all points y = -4E-05x 2 -0.001x + 0.0057 R 2 = 0.0111 -0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 -60 -40 -20 0 20 40 TM IN obs EM A J error Series1 Linear(S eries1) Poly.(Series1) TM IN,EMIN allpoints y = 0.0034x -0.5871 R 2 = 0.2529 y = -4E -05x 2 + 0.003x -0.5694 R 2 = 0.2664 -1 -0.8 -0.6 -0.4 -0.2 0 -60 -40 -20 0 20 40 TM IN obs EM IN error S eries1 Linear(S eries1) P oly.(Series1) Scale factor and nearly zero flexure for major axis Major axis azimuthal and elevation corrections are small Little correction is needed for collimation and for non-perpendicularity of the major and minor axes. Scale factor and correction for flexure of the minor axis 26 E Feedbox 26 W Feedbox Feedboxes have AC power, coax, fiber and appropriate cabling as required by receiver configuration. EMIN vs. TMIN Curve = tube flexure for minor axis = -0.360 Slope = minor scale factor = 15.48 arcsec Using the models, both telescopes now Point to within 2 arcminutes and Track to better than within 1 arcminute per hour EMAJ vs. TMAJ Curve = tube flexure for major axis = 0.036 Slope = major axis scale factor = 23.76 arcsec EMIN vs. TMAJ Curve = elevation misalignment in = 0.144 Slope = azimuth misalignment in = - 10.08 arcsec EMAJ vs. TMIN Curve = collimation = 0.144 Slope = non- perpendicularity of the axes = -2.88
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Transcript of J. D. Cline 1, M. W. Castelaz 1, A. Castelaz 2,3 1 PARI; 2 Summer Research Student at PARI; 3 Webb...
J. D. Cline1, M. W. Castelaz1, A. Castelaz2,3
1PARI; 2Summer Research Student at PARI; 3Webb Institute of Naval Architecture
Two 26 Meter Radio Telescopes for Long-Term Monitoring Programs and Surveys
Not-for-profit public
foundationwww.pari.edu
The 26 m radio telescopes • Installed by NASA for the Gemini and Apollo programs. • In excellent condition because of rigorous and
consistent periodic maintenance since that time. • Motion controls have been upgraded for astronomical
use.This poster presents
• The new control system• The pointing models• FeedBox infrastructure support• Current research• New research initiative
IntroductionIntroduction
Current ResearchCurrent Research
Pointing ModelsPointing Models
See http://www.pari.edu/ for more information
• Each telescope follows an alt-alt coordinate system.
• The major axis moves the telescope East-West.
• The minor axis moves the telescope North-South.
• DFM Engineering telescope control system.
• Installed on 26 East antenna in 2001 and 26 West antenna in 2002.
Session 49.04 Tuesday, January 11, 2005. AAS 205th Meeting
Pulsars
• Dr. David Moffett, Furman University, PI.
• 327 MHz receiver installed on 26 East antenna.
• Timings of a dozen pulsars.Methanol Maser Survey• Dr. Mel Blake, PARI, PI.• 6.7 GHz receiver installed on 26 West antenna.• Unbiased single-dish survey of northern hemisphere sky.• Currently in the process of receiver calibration.
The New Control System The New Control System
Major Axis
Minor Axis
Control of both antenna are linked to a central computer which
• Controls the telescopes separately or as a common pair.
• Drives a telescope in raster scan mode for mapping.
• Allows user-defined catalogs.• Uses either Equatorial or
Galactic coordinates.• Define track rates.
Telecontrol on the central computer. Features standard telescope control items including:
• Equatorial and GalacticCoordinates
• Time• Telescope Status• User Catalog• Weather
Pisgah Astronomical Research Institute is a not-for-profit public foundation located on 200 acres in Western North Carolina in the Pisgah National Forest.
Two 26 m radio telescopes on a 300 m nearly east-west baseline
26 West Antenna
26 East Antenna
New Research InitiativeNew Research InitiativeExtreme Scattering Events (ESEs) and Intra-Day
Variables (IDVs). Brian Dennison, UNC-Asheville, PI.
• Long-term monitoring of interstellar turbulence via its effect on scattering of radio waves over a large sample of compact sources.
• Two element interferometer to reduce noise confusion and measure point sources.
• Two frequencies, 2.4 GHz and 8.4 GHz.
FeedBox InfrastructureFeedBox Infrastructure
Pointing Models Correct for• Non-perpendicularity of radio axis to
minor axis • Non-perpendicularity of minor to major axes• Elevation misalignment in both axes • Azimuth misalignment in both axes • Encoder eccentricity and phase angle • Tube flexure in both axes
Procedure for Pointing Model • Point the telescope at radio point sources
throughout the sky and record observed Major and Minor axis positions.
• Difference Observed and Catalog Positions. • Plot differences with catalog positions. • Fit the plots with second order polynomials –
coefficients are pointing model parameters
EMIN = difference between Minor axis observed and catalog position
EMAJ = difference between Major axis observed and catalog position
TMIN = Minor Axis Observed Position
TMAJ =Major Axis Observed Position
TMAJ,EMAJ all points
y = 0.0069x + 0.011
R2 = 0.9265
y = 5E-06x2 + 0.0068x + 0.0066
R2 = 0.9272
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-100 -50 0 50 100
TMAJ obs
EM
AJ
erro
r
Series1
Linear (Series1)
Poly. (Series1)
TMAJ,EMIN all points
y = 2E-05x2 - 0.0019x - 0.6292
R2 = 0.1502-1
-0.8
-0.6
-0.4
-0.2
0
-100 -50 0 50 100
TMAJ obs
EM
IN e
rror Series1
Linear (Series1)
Poly. (Series1)
TMIN,EMAJ all points
y = -4E-05x2 - 0.001x + 0.0057
R2 = 0.0111
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-60 -40 -20 0 20 40
TMIN obs
EM
AJ
err
or
Series1
Linear (Series1)
Poly. (Series1)
TMIN,EMIN all points
y = 0.0034x - 0.5871
R2 = 0.2529
y = -4E-05x2 + 0.003x - 0.5694
R2 = 0.2664
-1
-0.8
-0.6
-0.4
-0.2
0
-60 -40 -20 0 20 40
TMIN obs
EM
IN e
rror Series1
Linear (Series1)
Poly. (Series1)
Scale factor and nearly zero flexure for major axis
Major axis azimuthal and elevation corrections are small
Little correction is needed for collimation and for non-perpendicularity of the major and minor axes.
Scale factor and correction for flexure of the minor axis
26 E Feedbox 26 W Feedbox
Feedboxes have AC power, coax, fiber and appropriate cabling as
required by receiver configuration.
EMIN vs. TMINCurve = tube flexure for minor axis = -0.360Slope = minor scale factor = 15.48 arcsec
Using the models, both telescopes now Point to within 2 arcminutes and Track to better than within 1 arcminute per hour
EMAJ vs. TMAJCurve = tube flexure for major axis = 0.036 Slope = major axis scale factor = 23.76 arcsec
EMIN vs. TMAJCurve = elevation misalignment in = 0.144Slope = azimuth misalignment in = -10.08 arcsec
EMAJ vs. TMINCurve = collimation = 0.144Slope = non- perpendicularity of the axes = -2.88
