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The Legacy of BIMA and the Challenge of CARMA

The Legacy of BIMA and the Challenge of CARMA. Jason Kirk – University of Illinois Cardiff Astro-Chemistry 2005. Interferometer Arrays The BIMA Consortium BIMA Details Example Results The hunt for large molecules Magnetic Field in SF regions Subarcsecond imagining of discs

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The Legacy of BIMA and the Challenge of CARMA

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  1. The Legacy of BIMA and the Challenge of CARMA Jason Kirk – University of Illinois Cardiff Astro-Chemistry 2005

  2. Interferometer Arrays The BIMA Consortium BIMA Details Example Results The hunt for large molecules Magnetic Field in SF regions Subarcsecond imagining of discs Combined LINEAR Observations Interlude: ATA OVRO (6 dishes) SZA (8 dishes) CARMA Ceder Flats Antenna Locations Relative Performance Imaging with CARMA Moving BIMA Summery Outline

  3. Interferometer Arrays (1/2) Why? • Achieve the ultra-high resolution of an unfeasibly large telescope at a fraction of the cost How? • Pair of telescopes (Baselines) – sample brightness distribution at a point in Fourier space (u,v) • Length of baseline is inversely proportional to the spatial scale sampled • Earth rotation • Given a “sufficient” sample of points in Fourier space their inversion will give a representation of the original brightness distribution

  4. Interferometer Arrays (2/2) Limitations? • “Zero order spacing” / Spatial sampling • Technical Complexity • Data reduction – phase and amplitude calibration • Data rate • Different methods of inversion/cleaning/processing Examples: • MERLIN, VLA, VLBI, SMA, IRAM, KECK

  5. BIMA consortium Radio Astronomy Laboratory of the University of California at Berkeley Laboratory for Astronomical Imaging of the University of Illinois Laboratory for Millimeter Astronomy of the University of Maryland, Financed by the US National Science Foundation Berkeley Illinois Maryland Array

  6. BIMA Details (1/2) • Ten element (45-baselines) interferometer array located at Hat Creek, California • First light 3-element array in 1985, 9 element array in 1995, 10-elements in 1996 (“Telescope No. 3”) • Operates as 1mm (210-270 GHz ) and 3mm (70-116 GHz ) depending on weather conditions • Four standard arrays (A-D) with resolutions 0.4, 2, 6, 14 arcsec at 100 GHz • Baselines ranging from 7m to 1.3 km • 2 arcmin Field of View (Primary Beam)

  7. BIMA Details (2/2) • 90-900 MHz IF Bandwidth • Up to 4 spectral window in each sideband (mirrored) • Window bandwidths: 6.25 / 12.5 / 25 / 100 MHz • 1024 channels split between the four windows depending on correlator mode • Observation parameterized by customized c-shell environment • Data reduction via the MIRIAD package • 30% of time reserved for visitor projects

  8. Ex 1: The hunt for large molecules (1/2) Remijan, Shiao, Friedel, Meier and Snyder, 2004, ApJ, 617, 384-398 Hunting for pre-biotic molecules in high-mass star formations regions. Including Formic and Acetic Acids because they structurally resemble glycine

  9. Ex 1: The hunt for large molecules (2/2) Detected two new sources of formic acid towards G19.61-0.23 and W75

  10. EX 2:Magnetic fields Lai, Crutcher, Girart & Rao, 2002, ApJ, 566, 925

  11. Ex 3: Subarcsecond imagining of discs Looney, Mundy and Welch, 2000, ApJ, 529, 477 First subarcsecond continuum imaging at 2.7mm of 24 protostellar disc systems HL Tauri

  12. EX 4: Combined LINEAR Observations • Hogerheijde et al, 2004, AJ, 127, 2406 • In “single dish mode” detected weak CN J=1-0 emission from comet C/1999/LINEAR S4 before comet break-up, no emission detected afterwards • Observations from BIMA and OVRO were combined in software to create a virtual array. Data reduction and process challenges were met, but unfortunately the emission was just too faint

  13. BIMA Summer School • Yearly summer school in interferometer array operation run by the BIMA consortium • Array totally given over to teaching for a week • Open to undergrads, postgrad, and postdocs • Now ended, keep an eye out for CARMA Summer Schools

  14. Interlude: ATA • Allen Telescope Array • Will replace BIMA at Hat Creek • 350 6.1-meter dishes • Press coverage driven by Paul Allen’s contribution to SETI, but will include a strong traditional science operation • A number of different theoretical array configurations were considered, but it was found that a random spread across the Hat Creek site was as good as any deliberate shaped array

  15. OVRO • Owens Valley Radio Observatory operated by Caltech University • Six 10.4-meter diameter dishes • Maximum baselines of 200 north-south and east-west • Comparable spectrographic and correlator capabilities of BIMA

  16. SZA • Sunyaev-Zeldovich Array • Eight close packed 3.5m telescopes • PI: John Carlstrom • First untargeted SZE survey hunting for galaxy clusters (over 12-square degrees) • Initially set up at OVRO • Will move to join CARMA after a few years

  17. CARMA • Combined Array for Research in Millimeter-wave Astronomy (CARMA) • Two potential arrays: • CARMA-15 : BIMA + OVRO • CARMA-23 : BIMA + OVRO + SZA • New higher site – reduction of atmospheric effects gives a doubling of effective surface area • SZA will be placed 30m to the side of the CARMA-15 array 0,0 position

  18. Ceder Flats / Environmental Report

  19. Antenna Locations • 5 planned arrays • A - ~2km • B – 1km • C – 350m • D – 150m • E – 65m • 25 pads at initial roll out • BIMA telescopes moved already • OVAO telescopes move in March • SZA moves around ‘07 • NSF site visit Aug ‘05 – planned prototype array using OVRO correlator Figure from Wright, 2004, BIMA Memo #101

  20. CARMA-23 UV Coverage Dec = +30 (right), –30 (above)

  21. Overview of (Sub)MM Arrays Array Collecting Area Correlator Receivers Tsys 226 m2 2 GHz/SB 230, 345, 100-200 K (488 m2 w/ 0.8 MHz ch. 650 GHz 200-400 K JCMT,CSO) DSB SIS >2000 K (650) 1060 m2 4 GHz/SB 115, 150, 230 100 to 2 MHz ch 345 GHz DSB 300 K (07+ 8 line) DP SIS (05/06) >5655 m2 8 GHz/SB 115, 230, 345, 60 to 120 K (>50 12m) >1024 ch. 650 GHz DP at 3/1.3mm SSB/DSB (bsl) 764 m2 4 GHz/SB 115, 230 GHz (841 m2 SIS DSB w/SZA) 3mm MMIC 4205m, 500m 2560m 408m 5000m 10km 2225m >2km

  22. Relative performance of CARMA

  23. Imaging with CARMA Sample simulation of Saturn using C and D arrays + the SZA (Helfer, 2004, CARMA Memo #20)

  24. Moving BIMA (1/3)

  25. Moving BIMA (2/3)

  26. Moving BIMA (3/3)

  27. Summary • BIMA was a ten-element interferometer at Hat Creek, CA operating at 1mm and 3mm • Relocation of BIMA dishes to a new higher site and integration with OVRO and SZA antenna to create CARMA • BIMA has moved, OVRO will soon move, work has begun on site utilities and antenna platforms • First science on new site planned by year’s end, full involvement of SZA by 2007

  28. BIMA Definition Paper: Welsh et al., 1996, PASP 108, 93 BIMA Homepage: http://bima.astro.umd.edu/ OVRO Homepage: http://www.ovro.caltech.edu/ SZA Homepage: http://astro.uchicago.edu/sza/ CARMA Homepage: http://www.mmarray.org/ Miscellaneous photographs are from the BIMA and CARMA websites. The CARMA simulation video (in AVI and MPEG formats) that was shown with the original version of this talk can be found online at http://www.mmarray.org/images/sims/sims.html. Further Information...

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