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CARMA

CARMA. Dick Plambeck UC Berkeley (for the CARMA consortium) www.mmarray.org. Berkeley-Illinois-Maryland Assn. array 10 6.1-m diameter antennas. Caltech array 6 10.4-m antennas. + UChicago SZA 8 3.5-m antennas. OVRO D. Woody S. Scott J. Lamb D. Hawkins

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CARMA

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  1. CARMA Dick Plambeck UC Berkeley (for the CARMA consortium) www.mmarray.org

  2. Berkeley-Illinois-Maryland Assn. array 10 6.1-m diameter antennas Caltech array 6 10.4-m antennas + UChicago SZA 8 3.5-m antennas

  3. OVRO D. Woody S. Scott J. Lamb D. Hawkins J. Carpenter A. Sargent G. Blake N. Scoville people project manager: Tony Beasley Berkeley • D. Plambeck • M. Wright • A. Bolatto • C. Kraybill • M. Fleming • L. Blitz • W.J. Welch Maryland • M. Pound • P. Teuben • K. Rauch • S. Vogel • L. Mundy • A. Harris Illinois • R. Plante • D. Mehringer • L. Snyder • R. Crutcher • L. Looney + programmers, engineers, technicians, postdocs, graduate students

  4. antennas 3 different antenna diameters - a heterogeneous array • exploit new algorithms for mosaicing, high fidelity imaging • sensitive to wide range of spatial frequencies; image large objects

  5. M33

  6. BIMA mosaic of M33 • CO 1-0 115 GHz • 759 pointing centers

  7. BIMA mosaic of M33 • 148 GMCs detected • overlie HI filaments (HI image: Deul & van der Hulst 1987)

  8. receiver bands for the 1mm and 3mm bands: • 4 GHz bandwidth, 1 polarization at first light • continuum sensitivity: 2-3 mJy/beam, in 1 minute • 230 GHz brightness sensitivity: 1 K for 1 km/sec channel, 1'' beam, in 1 hour

  9. site selection and acquisition requirements: • within 60 minute drive of existing OVRO infrastructure • elevation 7000-9000 ft for good atmospheric transmission but low snow load • 400-m diam flat area, + baselines to 2 km • avoid environmental battles all such sites are in Inyo National Forest, require Environmental Impact Report

  10. Cedar Flat OVRO Juniper Flat environmental studies done for 2 sites

  11. Juniper Flat – 7900’

  12. Cedar Flat – 7300’

  13. Cedar Flat: 20 min drive to OVRO on paved road, maintained (and plowed) by Caltrans simulated antenna Highway 168

  14. 225 GHz Percentiles 25% < 0.12 50% < 0.16 75% < 0.28

  15. array configurations • 5 antenna configurations, approx 55 pads • 2 km max baseline

  16. Cedar FlatE-array(most compact)synth beam 4.5" at 230 GHz Highway 168

  17. D-arraysynth beam 1.8"

  18. C-arraysynth beam 0.8"

  19. B-arraysynth beam 0.32"

  20. A-array synth beam 0.13"

  21. A-array u,v coverage for declination –30 10-m antennas only (15 baselines)

  22. u,v coverage for declination –30 10-m vs 10-m, 6-m vs 6-m antennas only(60 baselines)

  23. u,v coverage for declination –30 correlate all antennas (105 baselines)

  24. A-array synthesized beam, declination –30 0.26 × 0.14" FWHM 5% contours

  25. BIMA detection of 86 GHz radio flare in Orion • 20 Jan 2003 • beam 0.9 x 0.5'' Bower et al 2003

  26. 86 GHz flux increased from 40 mJy to 140 mJy in ~ 4 hrs 20 Jan 2003 02-06 UT 20 Jan 2003 06-10 UT

  27. BIMA antennas within collision range SZA provides even shorter spacings combine with single dish measurements from 10.4-m antennas most compact array

  28. avoid ‘custom’ vehicle 50% of weight on tow vehicle for traction antenna transporter

  29. transporter tow vehicle: 6-wheel drive military truck (Oshkosh MTVR)

  30. Current Concept antenna transporter

  31. fiberoptics • all communication with antennas via 8 singlemode optical fibers • length change with temperature is 1 part in 105 – need round trip phase measurement • based on existing BIMA system

  32. diurnal changes in fiber length (BIMA data from July 2002) fiber lengths Sun hits fibers • 135’ of fiber at outdoor air temp ( = 200 nsec) •  ~ 2 psec/C •  ~ 180°/C at 230 GHz outdoor air temp

  33. synth cpl laser TRX fiber 1 cpl RX phslck ref MXR RX fiber 2  BIMA round trip phase measurement advantage: no electronics at the antenna, just a fiber coupler disadvantage: lengths of fibers 1 and 2 must track with temperature and flexure (requires loose tube fiber)

  34. fiber lengths in each cable track each other within fraction of picosecond other cables 3 fibers in one cable

  35. raw phases on 3c454.3 through sunrise

  36. phases on 3c454.3 through sunrise after correction

  37. Caltech Cobra correlator • based on FPGAs, not custom correlator chips • 4 GHz bandwidth • 256 channels, 20 MHz resolution • 15 baselines

  38. CARMA first light correlator • uses Cobra hardware design • 15 telescopes, 105 baselines • 8 independent sections: • may be positioned anywhere in 4 GHz IF band • choose 2, 8, 31, 62, 125, 250, or 500 MHz bandwidth • velocity resolution 0.04 to 40 km s-1/ channel at 1.3 mm separateSZA correlator: 8 antennas, 28 baselines, 8 GHz bandwidth

  39. Cobra: each board handles 5 baselines, 500 MHz/baseline, 32 chans/baselineCARMA: reprogram FPGAs to handle 10 baselines, add spectral line capability

  40. graduate student training John Carlstrom Leslie Looney

  41. BIMA summer school

  42. public outreach

  43. BIMA antenna move • build new antenna bases (compatible with pad design, transporter) at high site • dismantle antennas at Hat Creek, load onto trucks: 2 trucks/antenna • 1 convoy = 2 trucks; travel time 4-5 days • entire antenna move approx 8 weeks

  44. moving the BIMA antennas: keep dish and feed legs intact

  45. OVRO antennas will be dismantled to pass through “the narrows”

  46. timeline

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