Cosmic Background Imager

Last update: 5 Feb 2009

Visit the Official CBI Homepage and the CBI Publication Page (Caltech)

Sievers, J.S., et al. (2009) Cosmological Results from Five Years of 30 GHz CMB Intensity Measurements with the Cosmic Background Imager submitted to ApJ (2009); arXiv:0901.4540 (astro-ph)
Mason, B.S., et al. (2009) A 31 GHz Survey of Low-Frequency Selected Radio Sources submitted to ApJ (2009); arXiv:0901.4330 (astro-ph)
Dickinson, C., et al. (2009) Anomalous Microwave Emission from the HII region RCW175 ApJ, 690, 1585-1589 (2009); arXiv:0807.3985 (astro-ph)
Mahdavi, A., et al. (2007) Joint Analysis of Cluster Observations: I. Mass Profile of Abell 478 from Combined X-ray, Sunyaev-Z'eldovich, and Weak Lensing Data ApJ, 664, 162-180 (2007); astro-ph/0703372
Sievers, J.L., et al. (2007) Implications of the Cosmic Background Imager Polarization Data ApJ, 660, 976-987 (2007); astro-ph/0509203
Myers, S.T., et al. (2006) Interferometric polarimetry of the comic microwave background: Methodology New Astronomy Reviews, 50, 951-959 (2006); preprint version here
Rajguru, N., et al. (2005) CMB observations from the CBI and VSA: A comparison of coincident maps and parameter estimation methods MNRAS, 363, 1125-1135 (2005); astro-ph/0502330
Bond, J.R., et al. (2005) The Sunyaev-Zeldovich effect in CMB-calibrated theories applied to the Cosmic Background Imager anisotropy power at l > 2000 ApJ, 626, 12-30 (2005); astro-ph/0205386
Readhead, A.C.S., et al. (2004b) Polarization Observations with the Cosmic Background Imager Science, 306, 836-844 (2004); astro-ph/0409569
Udomprasert, P.S., Mason, B.S., Readhead, A.C.S., Pearson, T.J. (2004) An Unbiased Measurement of H0 through Cosmic Background Imager Observations of the Sunyaev-Zel'dovich Effect in Nearby Galaxy Clusters ApJ, 615, 63-81 (2004); astro-ph/0408005
Readhead, A.C.S., et al. (2004a) Extended mosaic observations with the Cosmic Background Imager ApJ, 609, 498-512 (2004); astro-ph/0402359
Mason, B.S., et al. (2003) The anisotropy of the microwave background to l=3500: Deep field observations with the Cosmic Background Imager ApJ, 591, 540-555 (2003); astro-ph/0205384
Pearson, T.J., et al. (2003) The anisotropy of the microwave background to l=3500: Mosaic observations with the Cosmic Background Imager ApJ, 591, 556-574 (2003); astro-ph/0205388
Myers, S.T., et al. (2003) A Fast Gridded Method for the Estimation of the Power Spectrum of the Cosmic Microwave Background from Interferometer Data with Application to the Cosmic Background Imager ApJ, 591, 575-598 (2003); astro-ph/0205385
Sievers, J.L., et al. (2003) Cosmological parameters from Cosmic Background Imager observations and comparisons with BOOMERANG, DASI, and MAXIMA ApJ, 591, 599-622 (2003); astro-ph/0205387
Padin, S., et al. (2002) The Cosmic Background Imager PASP, 114, 83-97 (2002); astro-ph/0110124
Padin, S., et al. (2001) First intrinsic anisotropy observations with the Cosmic Background Imager ApJ, 549, L1-L5 (2001); astro-ph/0012211

July 20, 2000   The nearby Volcan Lascar underwent a major eruption last week, and was caught in the act by Brian Mason and Tim Pearson! So far, this has not had an effect on CBI operations. (©2000 Caltech/CBI).

What's New:

NEW:The papers by Mason et al. and Sievers et al. (2009) bringing together all the CBI CMB temperature anisotropy data and foreground source measurements (with OVRO and GBT) are available as preprints at arXiv:0901.4540 (astro-ph) and arXiv:0901.4330 (astro-ph) (2/5/09)

The paper J. Sievers et al. (2005) "Implications of the Cosmic Background Imager Polarization Data" has been completed, presenting results from the total of 2.5 years of CBI polarization data. See the preprint at astro-ph/0509203. (9/8/05)

The CBI "high-ell" SZ Paper has finally been published in the Astrophysical Journal (ApJ, 626, 12). See the CBI Publication Page. (6/2/05)

The CBI Polarization Paper reporting the results from 2002-2004 has been published in Science and is available as a preprint at astro-ph/0409569. (9/23/04)

Window functions, inverse Fisher matrices, bandpowers, and offsets for log-normal approximation are available here for details! (7/10/02)

We held an NSF press conference today for our first-year results. See also the CBI press page for details! The preprints are available here. (5/23/02)

The first CBI paper has been published in the March 1 ApJ Letters: Padin et al. 2001, Astrophys. J. (Letters), 549, L1-L5. (3/1/01)

See the CBI results page for extra information (likelhoods, etc) (2/21/01)

The first CBI paper has been accepted for publication in ApJ Letters. See the preprint on astro-ph (12/11/00)

Images of the eruption of Volcan Lascar as seen from the CBI site are available! (7/20/00)

I am in Chile at the CBI site for a 3-week tour of duty - my first! This first night observing went well, and it was clear most of the night until clouds came about 4am. Lesson one - oxygen is good! (5/5/00)

The DASI has seen first light at the South Pole! (1/7/2000)

First light has been achieved with six antennas, four 1-GHz correlators, giving an image of Jupiter. (11/1/99)

The CBI instrument has been shipped to Chile. (8/6/99)

June 2000: The CBI is in the middle of its first winter of operations and so far all is GO! The CBI has been observing since January. (©2000 Caltech/CBI).

Actual observing from Pasadena! With 6 antennas and 3 1GHz bands opertational we observed calibrator sources and some short test scans on clusters. The sources were clearly detected in spite of 83% humidity and atmospheric temperatures of 40K at zenith! Martin Shepherds control programs are easy to use and powerful - next step, the analyis software to turn the uv-data into images. (4/2/99)

14 April 1998: A test raising of the CBI dome. (©1998 Caltech/CBI).

The drives are being installed on the mount. See latest construction photographs. (6/10/98)

Installation of the sailcloth for the dome is nearly complete (4/15/98).

The elevation ball-screw is installed, and the mount is nearly ready for the first pointing tests (3/27/98).

Be sure to see the latest construction photos

The CBI dome is up! (2/15/98)

The official CBI website at Caltech is now open (1/6/98)

The CBI antenna mount arrived at Caltech (12/1/97)

14 April 1998: Tony gives a balky reinforcing tube the patented "Readhead Whack". (©1998 CBI).

CBI Historical Overview:

The Cosmic Background Imager (CBI) is an instrument designed to make images of the cosmic microwave background radiation and to measure its statistical properties on angular scales from 5 arc minutes to one degree (spherical harmonic scales from l = 3000 down to l = 300).

The CBI is a 13-element interferometer mounted on a 6.5 meter platform operating in ten 1-GHz frequency bands from 26 GHz to 36 GHz. The instantaneous field of view of the instrument is 44 arcmin and its resolution ranges from 4.5 to 10 arcmin. A 9-hour observation with the CBI will yield an image covering a 2 2 field with rms noise of 2.4 mJy, which for a 10 arcmin beam corresponds to Delta_T/T = 3 10-6 rms. This is considerably below the level predicted by current theories and found in recent observations.

The spectral capabilities of the CBI will be used to look for and separate diffuse foreground synchrotron, free-free, and dust emission from the interstellar medium in our Galaxy. Unresolved extragalactic sources will be measured with the 40 meter telescope at the Owens Valley Radio Observatory, and subtracted from the CBI images.

The CBI will also be a powerful instrument for observing the Sunyaev-Zel'dovich scattering of background radiation photons by the hot electrons in clusters of galaxies. Measurements of this effect can be used to study the properties of the hot cluster gas and the evolution of clusters, and to measure the Hubble constant directly.

The CBI will be completed early in 1998. After a few months of tests on the Caltech campus in Pasadena, it will be disassembled and shipped to Chile, where it will be installed at an altitude of 5000 meters. A high, dry site is essential in order to reach the required sensitivity levels in a reasonable observing time.

The Principal Investigator for the CBI project is Tony Readhead (Caltech), and the Project Scientist is Steve Padin (Caltech). Other Caltech team members include John Cartwright, Tim Pearson, Walter Schaal, Martin Shepherd, and John Yamasaki. Other collaborators include John Carlstrom, Mark Dragovan, and Bill Holzapfel (University of Chicago), Steven Myers (University of Pennsylvania), and Marshall Joy (NASA MSFC).

The construction of the CBI has been made possible by the generous support of the National Science Foundation (award AST-9413935), the California Institute of Technology, Ronald and Maxine Linde, and Cecil and Sally Drinkward.

- project description, circa 1997 -

Other CBI "Related" Resources:

Official CBI Homepage (Caltech)

OVRO CMB Programs (UPenn/Caltech)

OVRO Sunyaev-Zeldovich Effect Studies (UPenn/Caltech)

DASI Homepage (U Chicago)

VSA - The Very Small Array (Cambridge)

MAT - The Mobile Anisotropy Telescope (UPenn)

Steven T. Myers