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

+ UChicago SZA 8 3.5-m antennas 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

people project manager: Tony Beasley 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

antennas 3 different antenna diameters - a heterogeneous array CARMA CARMA + SZA # antennas 15 23 # baselines 105 253 collecting area 773 m2 850 m2 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

M33

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

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

receiver bands freq (GHz) OVRO BIMA SZA for the 1mm and 3mm bands: 210-270 SIS 85-116 SIS (70-116) MMIC 29-37 HEMT 22 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

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

environmental studies done for 2 sites Cedar Flat Juniper Flat OVRO

Juniper Flat – 7900’

Cedar Flat – 7300’

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

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

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 Highway 168

D-array synth beam 1.8"

C-array synth beam 0.8"

B-array synth beam 0.32"

A-array synth beam 0.13"

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

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

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

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

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

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

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

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

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

Current Concept antenna transporter

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

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

BIMA round trip phase measurement synth laser TRX cpl RX MXR 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)

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

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

education and public outreach

graduate student training John Carlstrom Leslie Looney

BIMA summer school

public outreach

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

moving the BIMA antennas: keep dish and feed legs intact

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

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

Project Goal Build a new mm array emphasizing New science Improved continuum/spectral-line sensitivity Unique: Image on all angular scales: HR, Wide FOV Operational flexibility Student training - “hands-on” New instrumentation & observational techniques Public outreach

outline site antenna configurations antenna transporter correlator fiberoptic LO distribution scientific capabilities timeline