Atmospheric phase characteristics of the ALMA long baseline

Satoki Matsushita; Yoshiharu Asakik; Edward B. Fomalont; Denis Barkats; Stuartt A. Corder; Richard E. Hills; Rvohei Kawabe; Luke I. Maud; Koh Ichiro Morita; Bojan Nikolic; Remo P. Tilanus; Catherine Vlahakis

doi:10.1117/12.2231846

Atmospheric phase characteristics of the ALMA long baseline

Satoki Matsushita, Yoshiharu Asakik, Edward B. Fomalont, Denis Barkats, Stuartt A. Corder, Richard E. Hills, Rvohei Kawabe, Luke I. Maud, Koh Ichiro Morita, Bojan Nikolic, Remo P. Tilanus, Catherine Vlahakis

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

4 Scopus citations

Abstract

Atacama Large Millimeter/submillimeter Arraj (ALMA) is the world's largest millimeter / submilliineter (mm / submm) interferometer. Along with science observations, ALMA has performed several long baseline campaigns in the last ft years to characterize and optimize its long baseline capabilities, lo achieve full long baseline capability of ALMA, it is important to understand the characteristics of atmospheric phase fluctuation at long baselines, since it is believed to be the main cause of miii/siibiiiui image degradation. For the first time, we present detailed properties of atmospheric phase fluctuation at miii/subiiiiii wavelength from baselines up to 15 km in length. Atmospheric phase fluctuation increases as a function of baseline length with a power-law slope close to 0.6, and many of the data display a shallower slope (0.2 - 0.3) at baseline length greater than about 1 km. Some of the data, on the other hand, show a single slope up to the maximum baseline length of around 15 km. l he phase correction method based on water vapor radiometers (WV Rs) works well, especially for cases with preci pi table water vapor (PWV) greater than 1 mm. typicalh yielding a 50% decrease or more in the degree of phase fluctuation. However, significant amount of atmospheric phase fluctuation still remains after the WVH phase correction; about 200 micron in rnis excess path length (rms phase fluctuation iu unit of length) even at PWV less than 1 nun. This result suggests the existence of other non-water-vapor sources of phase fluctuation, and emphasizes the need for additional phase correction methods, such as band-To-band and/or fast switching.

Original language	English (US)
Title of host publication	Ground-Based and Airborne Telescopes VI
Editors	Heather K. Marshall, Helen J. Hall, Roberto Gilmozzi
Publisher	SPIE
ISBN (Electronic)	9781510601918
DOIs	https://doi.org/10.1117/12.2231846
State	Published - 2016
Externally published	Yes
Event	Ground-Based and Airborne Telescopes VI - Edinburgh, United Kingdom Duration: Jun 26 2016 → Jul 1 2016

Publication series

Name	Proceedings of SPIE - The International Society for Optical Engineering
Volume	9906
ISSN (Print)	0277-786X
ISSN (Electronic)	1996-756X

Other

Other	Ground-Based and Airborne Telescopes VI
Country/Territory	United Kingdom
City	Edinburgh
Period	6/26/16 → 7/1/16

Keywords

ALMA
Atmospheric phase fluctuation
Long baseline
Phase correction

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Condensed Matter Physics
Computer Science Applications
Applied Mathematics
Electrical and Electronic Engineering

Access to Document

10.1117/12.2231846

Cite this

Matsushita, S., Asakik, Y., Fomalont, E. B., Barkats, D., Corder, S. A., Hills, R. E., Kawabe, R., Maud, L. I., Morita, K. I., Nikolic, B., Tilanus, R. P., & Vlahakis, C. (2016). Atmospheric phase characteristics of the ALMA long baseline. In H. K. Marshall, H. J. Hall, & R. Gilmozzi (Eds.), Ground-Based and Airborne Telescopes VI Article 99064X (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 9906). SPIE. https://doi.org/10.1117/12.2231846

Atmospheric phase characteristics of the ALMA long baseline. / Matsushita, Satoki; Asakik, Yoshiharu; Fomalont, Edward B. et al.
Ground-Based and Airborne Telescopes VI. ed. / Heather K. Marshall; Helen J. Hall; Roberto Gilmozzi. SPIE, 2016. 99064X (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 9906).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Matsushita, S, Asakik, Y, Fomalont, EB, Barkats, D, Corder, SA, Hills, RE, Kawabe, R, Maud, LI, Morita, KI, Nikolic, B, Tilanus, RP & Vlahakis, C 2016, Atmospheric phase characteristics of the ALMA long baseline. in HK Marshall, HJ Hall & R Gilmozzi (eds), Ground-Based and Airborne Telescopes VI., 99064X, Proceedings of SPIE - The International Society for Optical Engineering, vol. 9906, SPIE, Ground-Based and Airborne Telescopes VI, Edinburgh, United Kingdom, 6/26/16. https://doi.org/10.1117/12.2231846

@inproceedings{657b930e4f6b4e3cb9d2b0487442297c,

title = "Atmospheric phase characteristics of the ALMA long baseline",

abstract = "Atacama Large Millimeter/submillimeter Arraj (ALMA) is the world's largest millimeter / submilliineter (mm / submm) interferometer. Along with science observations, ALMA has performed several long baseline campaigns in the last ft years to characterize and optimize its long baseline capabilities, lo achieve full long baseline capability of ALMA, it is important to understand the characteristics of atmospheric phase fluctuation at long baselines, since it is believed to be the main cause of miii/siibiiiui image degradation. For the first time, we present detailed properties of atmospheric phase fluctuation at miii/subiiiiii wavelength from baselines up to 15 km in length. Atmospheric phase fluctuation increases as a function of baseline length with a power-law slope close to 0.6, and many of the data display a shallower slope (0.2 - 0.3) at baseline length greater than about 1 km. Some of the data, on the other hand, show a single slope up to the maximum baseline length of around 15 km. l he phase correction method based on water vapor radiometers (WV Rs) works well, especially for cases with preci pi table water vapor (PWV) greater than 1 mm. typicalh yielding a 50% decrease or more in the degree of phase fluctuation. However, significant amount of atmospheric phase fluctuation still remains after the WVH phase correction; about 200 micron in rnis excess path length (rms phase fluctuation iu unit of length) even at PWV less than 1 nun. This result suggests the existence of other non-water-vapor sources of phase fluctuation, and emphasizes the need for additional phase correction methods, such as band-To-band and/or fast switching.",

keywords = "ALMA, Atmospheric phase fluctuation, Long baseline, Phase correction",

author = "Satoki Matsushita and Yoshiharu Asakik and Fomalont, {Edward B.} and Denis Barkats and Corder, {Stuartt A.} and Hills, {Richard E.} and Rvohei Kawabe and Maud, {Luke I.} and Morita, {Koh Ichiro} and Bojan Nikolic and Tilanus, {Remo P.} and Catherine Vlahakis",

note = "Publisher Copyright: {\textcopyright} 2016 SPIE.; Ground-Based and Airborne Telescopes VI ; Conference date: 26-06-2016 Through 01-07-2016",

year = "2016",

doi = "10.1117/12.2231846",

language = "English (US)",

series = "Proceedings of SPIE - The International Society for Optical Engineering",

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T1 - Atmospheric phase characteristics of the ALMA long baseline

AU - Matsushita, Satoki

AU - Asakik, Yoshiharu

AU - Fomalont, Edward B.

AU - Barkats, Denis

AU - Corder, Stuartt A.

AU - Hills, Richard E.

AU - Kawabe, Rvohei

AU - Maud, Luke I.

AU - Morita, Koh Ichiro

AU - Nikolic, Bojan

AU - Tilanus, Remo P.

AU - Vlahakis, Catherine

PY - 2016

Y1 - 2016

N2 - Atacama Large Millimeter/submillimeter Arraj (ALMA) is the world's largest millimeter / submilliineter (mm / submm) interferometer. Along with science observations, ALMA has performed several long baseline campaigns in the last ft years to characterize and optimize its long baseline capabilities, lo achieve full long baseline capability of ALMA, it is important to understand the characteristics of atmospheric phase fluctuation at long baselines, since it is believed to be the main cause of miii/siibiiiui image degradation. For the first time, we present detailed properties of atmospheric phase fluctuation at miii/subiiiiii wavelength from baselines up to 15 km in length. Atmospheric phase fluctuation increases as a function of baseline length with a power-law slope close to 0.6, and many of the data display a shallower slope (0.2 - 0.3) at baseline length greater than about 1 km. Some of the data, on the other hand, show a single slope up to the maximum baseline length of around 15 km. l he phase correction method based on water vapor radiometers (WV Rs) works well, especially for cases with preci pi table water vapor (PWV) greater than 1 mm. typicalh yielding a 50% decrease or more in the degree of phase fluctuation. However, significant amount of atmospheric phase fluctuation still remains after the WVH phase correction; about 200 micron in rnis excess path length (rms phase fluctuation iu unit of length) even at PWV less than 1 nun. This result suggests the existence of other non-water-vapor sources of phase fluctuation, and emphasizes the need for additional phase correction methods, such as band-To-band and/or fast switching.

AB - Atacama Large Millimeter/submillimeter Arraj (ALMA) is the world's largest millimeter / submilliineter (mm / submm) interferometer. Along with science observations, ALMA has performed several long baseline campaigns in the last ft years to characterize and optimize its long baseline capabilities, lo achieve full long baseline capability of ALMA, it is important to understand the characteristics of atmospheric phase fluctuation at long baselines, since it is believed to be the main cause of miii/siibiiiui image degradation. For the first time, we present detailed properties of atmospheric phase fluctuation at miii/subiiiiii wavelength from baselines up to 15 km in length. Atmospheric phase fluctuation increases as a function of baseline length with a power-law slope close to 0.6, and many of the data display a shallower slope (0.2 - 0.3) at baseline length greater than about 1 km. Some of the data, on the other hand, show a single slope up to the maximum baseline length of around 15 km. l he phase correction method based on water vapor radiometers (WV Rs) works well, especially for cases with preci pi table water vapor (PWV) greater than 1 mm. typicalh yielding a 50% decrease or more in the degree of phase fluctuation. However, significant amount of atmospheric phase fluctuation still remains after the WVH phase correction; about 200 micron in rnis excess path length (rms phase fluctuation iu unit of length) even at PWV less than 1 nun. This result suggests the existence of other non-water-vapor sources of phase fluctuation, and emphasizes the need for additional phase correction methods, such as band-To-band and/or fast switching.

KW - ALMA

KW - Atmospheric phase fluctuation

KW - Long baseline

KW - Phase correction

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DO - 10.1117/12.2231846

M3 - Conference contribution

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T3 - Proceedings of SPIE - The International Society for Optical Engineering

BT - Ground-Based and Airborne Telescopes VI

A2 - Marshall, Heather K.

A2 - Hall, Helen J.

A2 - Gilmozzi, Roberto

PB - SPIE

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Y2 - 26 June 2016 through 1 July 2016

ER -

Atmospheric phase characteristics of the ALMA long baseline

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Keywords

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