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.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 Introduction Current Research Pointing 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 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 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 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 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 Feedbox26 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