A high-resolution chirp transform spectrometer for microwave measurements

Hartogh, P.; Hartmann, G. K.

doi:10.1088/0957-0233/1/7/008

Cited by 68 publications

(43 citation statements)

References 10 publications

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“…An additional purpose of these observations was to test the performance and stability of the newly installed highresolution chirp transform spectrometer (CTSB) built at the Max Planck Institute for solar system Research (Hartogh & Hartmann 1990;Hartogh 1997a,b;Villanueva et al 2006) and to compare these observations to the results from the acousto-optical spectrometers. High spectral resolution is crucial for resolving the shape of rotational lines in comets and for studying the gas velocity and asymmetries related to nonisotropic outgassing and self-absorption effects.…”

Section: Observationsmentioning

confidence: 99%

A survey of volatile species in Oort cloud comets C/2001 Q4 (NEAT) and C/2002 T7 (LINEAR) at millimeter wavelengths

Küppers¹,

Hartogh²,

Rezac³

et al. 2013

A&A

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Section: Observationsmentioning

confidence: 99%

A survey of volatile species in Oort cloud comets C/2001 Q4 (NEAT) and C/2002 T7 (LINEAR) at millimeter wavelengths

Küppers¹,

Hartogh²,

Rezac³

et al. 2013

A&A

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“…The spectral resolution provided was 40 kHz for the CTS, and 934, 913 and 250 kHz for the AOSA, AOSB and AOSC. One of the purposes of the observations was to test the performance of the newly installed highresolution CTS built at the Max Planck Institute for Solar System Research (Hartogh & Hartmann 1990;Villanueva et al 2006). High spectral resolution is crucial for resolving the shape of rotational lines in comets and study the gas velocity and asymmetries related to non-isotropic outgassing.…”

Section: Observationsmentioning

confidence: 99%

Submillimetric spectroscopic observations of volatiles in comet C/2004 Q2 (Machholz)

Hartogh¹,

Jarchow²,

Rengel³

et al. 2012

A&A

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Context. Submillimeter spectroscopic observations of comets provide an important tool for understanding their chemical composition and enable a taxonomic classification. Aims. We aim to determine the production rates of several parent-and product volatiles and the 12 C/ 13 C isotopic carbon ratio in the long-period comet C/2004 Q2 (Machholz), which is likely to originate from the Oort Cloud. Methods. The line emission from several molecules in the coma was measured with high signal-to-noise ratio in January 2005 at heliocentric distance of 1.2 AU by means of high-resolution spectroscopic observations using the Submillimeter Telescope (SMT) at the Arizona Radio Observatory (ARO). Results. We have obtained production rates of several volatiles (CH 3 OH, HCN, H 13 CN, HNC, H 2 CO, CO, and CS) by comparing the observed and simulated line-integrated intensities. We calculated the synthetic profiles using a radiative transfer code that includes collisions between neutrals and electrons, and the effects of radiative pumping of the fundamental vibrational levels by solar infrared radiation. Furthermore, multiline observations of the CH 3 OH J = 7-6 series allow us to estimate the rotational temperature using the rotation diagram technique. We find that the CH 3 OH population distribution of the levels sampled by these lines can be described by a rotational temperature of 40 ± 3 K. Derived mixing ratios relative to hydrogen cyanide are CO/CH 3 OH/H 2 CO/CS/HNC/H 13 CN/HCN = 30.9/24.6/4.8/0.57/0.031/0.013/1 assuming a pointing offset of 8 due to the uncertain ephemeris at the time of the observations and the telescope pointing error. Conclusions. The measured relative molecular abundances in C/2004 Q2 (Machholz) are between low-to typical values of those obtained in Oort Cloud comets, suggesting that it has visited the inner solar system previously and undergone thermal processing. The HNC/HCN abundance ratio of ∼3.1% is comparable to that found in other comets, accounting for the dependence on the heliocentric distance, and could possibly be explained by ion-molecule chemical processes in the low-temperature atmosphere. From a tentative H 13 CN detection, the measured value of 97 ± 30 for the H 12 CN/H 13 CN isotopologue pair is consistent with a telluric value. The outgassing variability observed in the HCN production rates over a period of two hours is consistent with the rotation of the nucleus derived using different observational techniques.

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“…Similar to its predecessor, cWASPAM observes the rotational transition of the water molecule at 22.235 GHz. The vertical and horizontal polarisation components of the signal are simultaneously analysed with two Chirp Transform Spectrometer (CTS) backends (Hartogh and Hartmann, 1990;Villanueva and Hartogh, 2004;Villanueva et al, 2006;Paganini and Hartogh, 2009). The CTS are identical and have a bandwidth of 40 MHz which is divided into 4096 channels with a resolution of 14 kHz each.…”

Section: Instrumentmentioning

confidence: 99%

First detection of tidal behaviour in polar mesospheric water vapour by ground based microwave spectroscopy

Hallgren

Hartogh

2012

Atmos. Chem. Phys.

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Abstract. Mesospheric water vapour has been observed above ALOMAR in northern Norway (69 • N 16 • E) by our group since 1995 using a 22 GHz ground based microwave spectrometer. A new instrument with higher sensitivity, providing a much better time resolution especially in the upper mesosphere, was installed in May 2008. The time resolution is high enough to provide observations of daily variations in the water vapour mixing ratio. We present the first ground based detections of tidal behaviour in the polar middle atmospheric water vapour distribution.Diurnal and semidiurnal variations of water vapour have been observed and due to the long chemical lifetime of water they are assumed to be caused by changing wind patterns which transport water-rich or poor air into the observed region. The detected tidal behaviour does not follow any single other dynamical field but is instead assumed to be a result of the different wind components.Both the diurnal and semidiurnal amplitude and phase components are resolved. The former shows a stable seasonal behaviour consistent with earlier observations of wind fields and model calculations, whereas the latter appears more complex and no regular behaviour has so far been observed.

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A high-resolution chirp transform spectrometer for microwave measurements

Cited by 68 publications

References 10 publications

A survey of volatile species in Oort cloud comets C/2001 Q4 (NEAT) and C/2002 T7 (LINEAR) at millimeter wavelengths

A survey of volatile species in Oort cloud comets C/2001 Q4 (NEAT) and C/2002 T7 (LINEAR) at millimeter wavelengths

Submillimetric spectroscopic observations of volatiles in comet C/2004 Q2 (Machholz)

First detection of tidal behaviour in polar mesospheric water vapour by ground based microwave spectroscopy

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