CARMA: The Combined Array for Research in mm-wave Astronomy Tony Beasley NSF Review, July

Introduction Two decades – OVRO/BIMA arrays have pioneered field of mm interferometry Talks: remarkable achievements & ongoing development programs of individual facilities Early 90’s: shared interest in Sci/Ed benefits of merging the arrays led to “CARMA concept” Today: CARMA Project underway: overview 1 st : Technical/infrastructure development already directed towards new array – context Note: URO proposal under consideration includes transition and early CARMA operations

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

Key Features of CARMA Heterogeneous array (850 m 2 ) six 10.4m antennas - OVRO nine 6.1m antennas - BIMA eight 3.5m antennas – Uni. Chicago SZA Use four configs: 100m – 1500m + SZA Imaging over wide range of angular scales: CARMA: ”, SZA: 0.5-3’ More antennas  High-fidelity imaging + snapshot Mosaicing

Science Drivers Studies of circumstellar/protoplanetary disks, stellar outflows, evolved stars Examine environments of nearby & distant galaxies Explore Solar System: Sun, planets, comets, KBOs Probe astrochemistry of ISM, IPM Image distant universe: high-redshift galaxies Cosmology experiments (other talks…) CARMA: address key research areas + complement new instruments (NGST/EVLA/CELT/ALMA)

Example: high-resolution imaging of CO in the Virgo Cluster

Continuum Sensitivity (4 GHz BW, 2-pol) Angular Resolution & Line Sensitivity (1km/s channel, 1-pol) 100 GHz 230 GHz Freq GHz 1-min mJy 5-hr mJy Config Beam ” 1-min K 5-hr K Beam ” 1-min K 5-hr K D C (345) B A CARMA Sensitivity Summary Mins ~ K Hrs ~ sub-K

High-Altitude Site Lower atmospheric opacity, better phase stability: increase in observing time, speed Required: >7000’, 2-km baselines, 400-m central area, year-round access, low snow Owens Valley – high, dry locations with suitable topography – White/Inyo Mtns ’ : factor of two improvement in opacity statistics over existing sites (mean , number of days < given  etc.) – x4 integration time, year-round observing

Site Selection Initial candidate – Upper Harkless Flat Caltech studies, development Opposition – site dropped in strategy: analyze range of sites Initial sample  three candidates Juniper Flat (7900’) Cedar Flat (North & East -7300’) Lower Harkless Flat (7100’)

Juniper Flat – 7900’

Cedar Flat East – 7300’

Cedar Flat North – 7300’

Lower Harkless Flat – 7100’

 Percentiles 25% < % < % < 0.28 OV: Regional results consistent

Site Acquisition All sites on National Forest – federal NEPA UC participation – state CEQA Result: joint EIS/EIR document Considered: Botany/Wildlife/Cultural issues Strong community support Residual opposition: CNPS, ESAS, Big Pine tribe In general: CARMA strategy good, land use in the OV is complex issue…

Process Timeline SUP Application to INF – October 2001 NEPA/CEQA Formal Initiation – March 2002 Public Scoping process – June 2002 (draft EIS/EIR doc: October 2002) (final EIS/EIR: December 2002) (ROD/appeal period – March 2003) Site access: Spring 2003+

Array Developments New Site Antenna Transporter + Relocation plan First light: COBRA-based 4 GHz FPGA Correlator + 8GHz SZA continuum (flexible subarraying) SOA integrated 22GHz WVR phase correction LO/IF system – HEMT/SIS/MMIC? receivers New computing & archive system Upgrades: antenna drives & cryogenics, telemetry Development options: single dish, wideband BIMA IFs, polarization capability (other talks..)

Site layout

VRML simulation

Relay Station

Operations Model Site-dependent… General: similar to OVRO/BIMA model – observers/students/postdocs run array Generate own power - diesel Important: utilize/enhance existing infrastructure (kitchen, dorms, engineering facilities) Time allocation/observing policies: under consideration by SSC

Consortium Structure CARMA BOARD CARMA BOARD Science Steering Committee CARMA Director Antennas Transporter Woody Plambeck Site Beasley Relocation Fleming Woody Snyder LO/IF Plambeck Lamb Computing Scott Pound Crutcher WVR Harris Woody Plambeck Correlator Hawkins Project Manager A. Beasley Project Manager A. Beasley Working Groups: Science, Hardware, Software, Configuration Distributed design/development via , weekly telecons, f2f meetings, visits Website: - info, document archivewww.mmarray.org July 2002 – Project plan revision underway

Budget $M (2002) Correlator Site WVR Environmental Management/Admin Transporter Computing BIMA Relocation Technical Developments 15% Contingency (July 2002) $14.5M Funding: Caltech $5M, BIMA $5M, NSF $2.3M (+$2-3M TBI) Staffing for project development: URO operations grants

Schedule Design/analysis/scoping phase - past year BIMA/OVRO upgrades/retrofits - Fall 2002 New technical developments - Fall 2002 Milestone: Correlator PDR – November 2002 Site Award/construction – Spring 2003 Move OVRO to high site – Spring 2004 BIMA relocation – Spring/Fall 2004 Full Operations – Summer 2005

CARMA Next three years – upgrades, new technical developments & transition to single instrument/observatory operations - busy Maintaining/enhancing staffing levels critical to support project development Outstanding issue - site process – progressing well, resolution early next year CARMA: common vision/shared future, excited project & array potential

OVRO images