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CARMA

CARMA. Dick Plambeck UC Berkeley (for the CARMA consortium) www.mmarray.org URSI, 24 June 2003, Columbus, Ohio. 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

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CARMA

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  1. CARMA Dick Plambeck UC Berkeley (for the CARMA consortium) www.mmarray.org URSI, 24 June 2003, Columbus, Ohio

  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(Engargiola et al. 2003) • 148 GMCs detected • overlie HI filaments (HI image: Deul & van der Hulst 1987)

  8. receivers 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 diameter flat area, + baselines to 2 km • avoid environmental battles all such sites are in Inyo National Forest, require Environmental Impact Report

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

  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. BIMA antenna move • keep dish and feed legs in one piece • move 9 antennas in 8 weeks

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

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

  18. Cedar FlatE-array(most compact)synth beam 4.5" at 230 GHz array center

  19. BIMA antennas within collision range SZA provides even shorter spacings combine with single dish measurements from 10.4-m antennas to recover all spatial frequencies E-array

  20. A-array 0.13" synth beam

  21. u,v coverage for declination –30 4-hr observing track

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

  23. BIMA A-array detection of a stellar flare in Orion ( 86 GHz,synthesized beam 0.9 × 0.5" ) 20 Jan 2003 4 UT 20 Jan 2003 8 UT 30 mJy 150 mJy BN IRc2

  24. use common transporter for 6-m and 10-m antennas avoid ‘custom’ vehicle 50% of weight on tow vehicle for traction antenna transporter

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

  26. fiberoptics • all communication with antennas via 8 singlemode optical fibers • use standard SMF 28 fiber - length change with temperature is 1 part in 105 • use BIMA round trip phase measuring system to monitor fiber lengths

  27. 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

  28. 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)

  29. raw phases on 3c454.3 through sunrise

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

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

  32. 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

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

  34. timeline

  35. BIMA summer school

  36. Alberto Bolatto testing prototype WVR in Berkeley

  37. Leslie Looney pulling underground fiber for long baselines John Carlstrom repairing the Air Products refrigerator on receiver 3

  38. 7th graders at Hat Creek

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