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

+ UChicago SZA m antennas Berkeley-Illinois-Maryland Assn. array m diameter antennas Caltech array m antennas

people OVRO D. Woody S. Scott J. Lamb D. Hawkins J. Carpenter A. Sargent G. Blake N. Scoville 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 project manager: Tony Beasley

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 CARMACARMA + SZA # antennas1523 # baselines collecting area773 m m 2

M33

BIMA mosaic of M33 CO GHz 759 pointing centers

BIMA mosaic of M33 ( Engargiola et al. 2003) 148 GMCs detected overlie HI filaments (HI image: Deul & van der Hulst 1987)

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 freq (GHz)OVROBIMASZA SIS SISSIS (70-116)MMIC 29-37HEMT 22MMIC

site selection and acquisition requirements: within 60 minute drive of existing OVRO infrastructure elevation 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

Cedar Flat Juniper Flat OVRO environmental studies done for 2 sites

Juniper Flat – 7900’

Cedar Flat – 7300’

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

 Percentiles 25% < % < % < GHz

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

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

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

Cedar Flat E-array (most compact) synth beam 4.5" at 230 GHz array center

E-array 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

A-array 0.13" synth beam

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

A-array synthesized beam, declination – × 0.14" FWHM 5% contours

BIMA A-array detection of a stellar flare in Orion ( 86 GHz, synthesized beam 0.9 × 0.5" ) 20 Jan UT 20 Jan UT BN IRc2 30 mJy150 mJy

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

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

fiberoptics all communication with antennas via 8 singlemode optical fibers use standard SMF 28 fiber - length change with temperature is 1 part in 10 5 use BIMA round trip phase measuring system to monitor fiber lengths

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

BIMA round trip phase measurement synth laser TRX cpl RXMXR cplRX phslck ref  fiber 1 fiber 2 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)

raw phases on 3c454.3 through sunrise

phases on 3c454.3 through sunrise after correction

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

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 separate SZA correlator: 8 antennas, 28 baselines, 8 GHz bandwidth

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

timeline Jan 2003draft environmental document submitted Mar 2003Forest Service decision: Cedar Flat Jun 2003end of public comment period Aug 2003Forest Service record of decision Oct 2003appeals period ends early 2004SZA operational at high site mid 2004move OVRO and BIMA antennas to high site 2005begin operation

BIMA summer school

Alberto Bolatto testing prototype WVR in Berkeley

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

7th graders at Hat Creek