The cologne acousto optical spectrometers

Schieder, R.; Tolls, Volker; Winnewisser, G.

doi:10.1007/bf00457985

Cited by 79 publications

(36 citation statements)

References 2 publications

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“…We mapped the Perseus region simultaneously in 13 CO 2-1 and 12 CO 3-2 using the KOSMA 3 m submillimeter telescope on Gornergrat, Switzerland, equipped with a dual-channel SIS receiver (Graf et al 1998) and acousto optical spectrometers (Schieder et al 1989). Main beam efficiencies and half power beamwidths (HPBWs) are 68%, 130 at 220 GHz and 70%, 82 at 345 GHz.…”

Section: Observationsmentioning

confidence: 99%

A KOSMA 7 deg$\mathsf{^{2}}$ $\mathsf{^{13}}$CO 2–1 and $\mathsf{^{12}}$CO 3–2 survey of the Perseus cloud

Sun¹,

Krämer²,

Ossenkopf

et al. 2006

A&A

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Context. Characterizing the spatial and velocity structure of molecular clouds is a first step towards a better understanding of interstellar turbulence and its link to star formation. Aims. We present observations and structure analysis results for a large-scale (∼7.10 deg 2 ) 13 CO J = 2-1 and 12 CO J = 3-2 survey towards the nearby Perseus molecular cloud observed with the KOSMA 3 m telescope. Methods. We study the spatial structure of line-integrated and velocity channel maps, measuring the ∆-variance as a function of size scale. We determine the spectral index β of the corresponding power spectrum and study its variation across the cloud and across the lines. Results. We find that the spectra of all CO line-integrated maps of the whole complex show the same index, β ≈ 3.1, for scales between about 0.2 and 3 pc, independent of isotopomer and rotational transition. A complementary 2MASS map of optical extinction shows a noticeably smaller index of 2.6. In contrast to the overall region, the CO maps of individual subregions show a significant variation of β. The 12 CO 3-2 data provide e.g. a spread of indices between 2.9 in L 1455 and 3.5 in NGC 1333. In general, active star forming regions show a larger power-law exponent. We find that the ∆-variance spectra of individual velocity channel maps are very sensitive to optical depth effects clearly indicating self-absorption in the densest regions. When studying the dependence of the channel-map spectra as a function of the velocity channel width, the expected systematic increase of the spectral index with channel width is only detected in the blue line wings. This could be explained by a filamentary, pillar-like structure which is left at low velocities while the overall molecular gas is swept up by a supernova shock wave.

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Section: Observationsmentioning

confidence: 99%

A KOSMA 7 deg$\mathsf{^{2}}$ $\mathsf{^{13}}$CO 2–1 and $\mathsf{^{12}}$CO 3–2 survey of the Perseus cloud

Sun¹,

Krämer²,

Ossenkopf

et al. 2006

A&A

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“…Four tunerless balanced waveguide receivers have been designed to cover the entire 180-720 GHz frequency range. The IF bandwidth of the CSO receivers will increase from the current 1 GHz to 4 GHz, and interface to a newly acquired 4x1 GHz wide bandwidth Acousto-Optical Spectrometer (AOS), [1][2][3] build by the University of Köln. Dual frequency (2 color) observations in the 230/460 GHz and 345/660 GHz atmospheric frequency bands can be configured by routing the respective receiver IF output(s) to the Köln built hybrid AOS.…”

Section: Introductionmentioning

confidence: 99%

Heterodyne Instrumentation Upgrade at the Caltech Submillimeter Observatory

Kooi

Kovács

Bumble

et al. 2003

Millimeter and Submillimeter Detectors for Astronomy

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Balanced receivers are under development at the Caltech Submillimeter Observatory (CSO) for the 230/460 GHz and 345/660 GHz atmospheric windows. The mixers are tunerless, implemented in a balanced configuration, have a 4-8 GHz IF, and can be used in dual frequency observation mode. As shall be seen, the balanced arrangement provides a high level of amplitude noise immunity and allows all of the available LO power to be used. In turn, this permits complete automation of the receivers by means of synthesized LO source(s). A disadvantage of balanced mixers is, perhaps, that the sidebands at the IF remain convolved (DSB), unlike sideband separating (2SB) receivers. The latter, however are unbalanced and do not have the noise and LO injection advantages of balanced mixers. For the CSO, balanced mixers covering the range 180-720 GHz were judged most promising to facilitate many of the astrophysical science goals in the years to come.In parallel, a dual polarization 280-420 GHz continuous comparison (correlation) receiver is in an advanced state of development. The instrument has two beams on the sky; a reference and a signal beam. Using only cooled reflecting optics, two polarizing grids, and a quadrature hybrid coupler, the sky beams are coupled to four tunerless SIS mixers (both polarizations). The 4-12 GHz mixer IF outputs are, after amplification, correlated against each other. In principle, this technique results in flat baselines with very low RMS noise, and is especially well suited for high redshift Galaxy work.Not only do these changes greatly enhance the spectroscopic capabilities of the CSO, they will also enable the observatory to be integrated into the Harvard-Smithsonian Submillimeter Array (SMA), as an additional telescope.Keywords: Balanced mixer theory, continuous comparison receiver, radial probe, full-height waveguide to thinfilm microstrip transition, split-block, high current density superconducting-insulating-superconducting (SIS) tunnel junction, broad bandwidth quadrature waveguide hybrid, DC-break, IF match, Wilkinson in phase power combiner, Low noise amplfier (LNA), 4-8 GHz intermediate frequency (IF).

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“…It possess a fluctuation bandwidth δ f l of 1.3 MHz and an IF bandwidth B of 1.4 GHz, defining the IF bandwidth of the entire instrument. AOSs were developed and assembled at our institute [24] and have been applied successfully for many years for various purposes in the field of radio-astronomy and spectroscopy [1,25,26]. Further analysis and data processing is performed by a PC.…”

Section: The Receiver Ichipsmentioning

confidence: 99%

Compact Setup of a Tunable Heterodyne Spectrometer for Infrared Observations of Atmospheric Trace-Gases

2013

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We report on the development and characterization of the new compact infrared heterodyne receiver, iChips (Infrared Compact Heterodyne Instrument for Planetary Science). It is specially designed for ground-based observations of the terrestrial atmosphere in the mid-infrared wavelength region. Mid-infrared room temperature quantum cascade lasers are implemented into a heterodyne system for the first time. Their tunability allows the instrument to operate in two different modes. The scanning mode covers a spectral range of few wavenumbers continuously with a resolution of approximately ν ∆ν ≥ 105 . This mode allows the determination of the terrestrial atmospheric transmission. The staring mode, applied for observations of single molecular transition features, provides a spectral resolution of ν ∆ν ≥ 10 7 and a bandwidth of 1.4 GHz. To demonstrate the instrument's capabilities, initial observations in both modes were performed by measuring the terrestrial transmittance at 7.8 µm (∼ 1,285 cm −1 ) and by probing terrestrial ozone features at 8.6 µm (∼ 1,160 cm −1 ), respectively. The receivers characteristics and performance are described.

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The cologne acousto optical spectrometers

Cited by 79 publications

References 2 publications

A KOSMA 7 deg$\mathsf{^{2}}$ $\mathsf{^{13}}$CO 2–1 and $\mathsf{^{12}}$CO 3–2 survey of the Perseus cloud

A KOSMA 7 deg$\mathsf{^{2}}$ $\mathsf{^{13}}$CO 2–1 and $\mathsf{^{12}}$CO 3–2 survey of the Perseus cloud

Heterodyne Instrumentation Upgrade at the Caltech Submillimeter Observatory

Compact Setup of a Tunable Heterodyne Spectrometer for Infrared Observations of Atmospheric Trace-Gases

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