The Atacama Cosmology Telescope

Beam measurements and the microwave brightness temperatures of Uranus and Saturn

Matthew Hasselfield, Kavilan Moodley, J. Richard Bond, Sudeep Das, Mark J. Devlin, Joanna Dunkley, Rolando Dünner, Joseph W. Fowler, Patricio Gallardo, Megan B. Gralla, Amir Hajian, Mark Halpern, Adam D. Hincks, Tobias A. Marriage, Danica Marsden, Michael D. Niemack, Michael R. Nolta, Lyman A. Page, Bruce Partridge, Benjamin L. Schmitt & 6 others Neelima Sehgal, Jon Sievers, Suzanne T. Staggs, Daniel S. Swetz, Eric R. Switzer, Edward J. Wollack

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

We describe the measurement of the beam profiles and window functions for the Atacama Cosmology Telescope (ACT), which operated from 2007 to 2010 with kilopixel bolometer arrays centered at 148, 218, and 277 GHz. Maps of Saturn are used to measure the beam shape in each array and for each season of observations. Radial profiles are transformed to Fourier space in a way that preserves the spatial correlations in the beam uncertainty to derive window functions relevant for angular power spectrum analysis. Several corrections are applied to the resulting beam transforms, including an empirical correction measured from the final cosmic microwave background (CMB) survey maps to account for the effects of mild pointing variation and alignment errors. Observations of Uranus made regularly throughout each observing season are used to measure the effects of atmospheric opacity and to monitor deviations in telescope focus over the season. Using the WMAP-based calibration of the ACT maps to the CMB blackbody, we obtain precise measurements of the brightness temperatures of the Uranus and Saturn disks at effective frequencies of 149 and 219 GHz. For Uranus we obtain thermodynamic brightness temperatures 106.7 ± 2.2 K and 100.1 ± 3.1 K. For Saturn, we model the effects of the ring opacity and emission using a simple model and obtain resulting (unobscured) disk temperatures of 137.3 ± 3.2 K and 137.3 ± 4.7 K.

Original languageEnglish (US)
Article number17
JournalAstrophysical Journal, Supplement Series
Volume209
Issue number1
DOIs
StatePublished - Nov 1 2013

Fingerprint

Uranus (planet)
Uranus
brightness temperature
Saturn
cosmology
telescopes
microwaves
opacity
bolometers
transform
profiles
thermodynamics
calibration
spectrum analysis
power spectra
alignment
deviation
effect
microwave
rings

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Hasselfield, Matthew ; Moodley, Kavilan ; Bond, J. Richard ; Das, Sudeep ; Devlin, Mark J. ; Dunkley, Joanna ; Dünner, Rolando ; Fowler, Joseph W. ; Gallardo, Patricio ; Gralla, Megan B. ; Hajian, Amir ; Halpern, Mark ; Hincks, Adam D. ; Marriage, Tobias A. ; Marsden, Danica ; Niemack, Michael D. ; Nolta, Michael R. ; Page, Lyman A. ; Partridge, Bruce ; Schmitt, Benjamin L. ; Sehgal, Neelima ; Sievers, Jon ; Staggs, Suzanne T. ; Swetz, Daniel S. ; Switzer, Eric R. ; Wollack, Edward J. / The Atacama Cosmology Telescope : Beam measurements and the microwave brightness temperatures of Uranus and Saturn. In: Astrophysical Journal, Supplement Series. 2013 ; Vol. 209, No. 1.
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abstract = "We describe the measurement of the beam profiles and window functions for the Atacama Cosmology Telescope (ACT), which operated from 2007 to 2010 with kilopixel bolometer arrays centered at 148, 218, and 277 GHz. Maps of Saturn are used to measure the beam shape in each array and for each season of observations. Radial profiles are transformed to Fourier space in a way that preserves the spatial correlations in the beam uncertainty to derive window functions relevant for angular power spectrum analysis. Several corrections are applied to the resulting beam transforms, including an empirical correction measured from the final cosmic microwave background (CMB) survey maps to account for the effects of mild pointing variation and alignment errors. Observations of Uranus made regularly throughout each observing season are used to measure the effects of atmospheric opacity and to monitor deviations in telescope focus over the season. Using the WMAP-based calibration of the ACT maps to the CMB blackbody, we obtain precise measurements of the brightness temperatures of the Uranus and Saturn disks at effective frequencies of 149 and 219 GHz. For Uranus we obtain thermodynamic brightness temperatures 106.7 ± 2.2 K and 100.1 ± 3.1 K. For Saturn, we model the effects of the ring opacity and emission using a simple model and obtain resulting (unobscured) disk temperatures of 137.3 ± 3.2 K and 137.3 ± 4.7 K.",
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Hasselfield, M, Moodley, K, Bond, JR, Das, S, Devlin, MJ, Dunkley, J, Dünner, R, Fowler, JW, Gallardo, P, Gralla, MB, Hajian, A, Halpern, M, Hincks, AD, Marriage, TA, Marsden, D, Niemack, MD, Nolta, MR, Page, LA, Partridge, B, Schmitt, BL, Sehgal, N, Sievers, J, Staggs, ST, Swetz, DS, Switzer, ER & Wollack, EJ 2013, 'The Atacama Cosmology Telescope: Beam measurements and the microwave brightness temperatures of Uranus and Saturn', Astrophysical Journal, Supplement Series, vol. 209, no. 1, 17. https://doi.org/10.1088/0067-0049/209/1/17

The Atacama Cosmology Telescope : Beam measurements and the microwave brightness temperatures of Uranus and Saturn. / Hasselfield, Matthew; Moodley, Kavilan; Bond, J. Richard; Das, Sudeep; Devlin, Mark J.; Dunkley, Joanna; Dünner, Rolando; Fowler, Joseph W.; Gallardo, Patricio; Gralla, Megan B.; Hajian, Amir; Halpern, Mark; Hincks, Adam D.; Marriage, Tobias A.; Marsden, Danica; Niemack, Michael D.; Nolta, Michael R.; Page, Lyman A.; Partridge, Bruce; Schmitt, Benjamin L.; Sehgal, Neelima; Sievers, Jon; Staggs, Suzanne T.; Swetz, Daniel S.; Switzer, Eric R.; Wollack, Edward J.

In: Astrophysical Journal, Supplement Series, Vol. 209, No. 1, 17, 01.11.2013.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The Atacama Cosmology Telescope

T2 - Beam measurements and the microwave brightness temperatures of Uranus and Saturn

AU - Hasselfield, Matthew

AU - Moodley, Kavilan

AU - Bond, J. Richard

AU - Das, Sudeep

AU - Devlin, Mark J.

AU - Dunkley, Joanna

AU - Dünner, Rolando

AU - Fowler, Joseph W.

AU - Gallardo, Patricio

AU - Gralla, Megan B.

AU - Hajian, Amir

AU - Halpern, Mark

AU - Hincks, Adam D.

AU - Marriage, Tobias A.

AU - Marsden, Danica

AU - Niemack, Michael D.

AU - Nolta, Michael R.

AU - Page, Lyman A.

AU - Partridge, Bruce

AU - Schmitt, Benjamin L.

AU - Sehgal, Neelima

AU - Sievers, Jon

AU - Staggs, Suzanne T.

AU - Swetz, Daniel S.

AU - Switzer, Eric R.

AU - Wollack, Edward J.

PY - 2013/11/1

Y1 - 2013/11/1

N2 - We describe the measurement of the beam profiles and window functions for the Atacama Cosmology Telescope (ACT), which operated from 2007 to 2010 with kilopixel bolometer arrays centered at 148, 218, and 277 GHz. Maps of Saturn are used to measure the beam shape in each array and for each season of observations. Radial profiles are transformed to Fourier space in a way that preserves the spatial correlations in the beam uncertainty to derive window functions relevant for angular power spectrum analysis. Several corrections are applied to the resulting beam transforms, including an empirical correction measured from the final cosmic microwave background (CMB) survey maps to account for the effects of mild pointing variation and alignment errors. Observations of Uranus made regularly throughout each observing season are used to measure the effects of atmospheric opacity and to monitor deviations in telescope focus over the season. Using the WMAP-based calibration of the ACT maps to the CMB blackbody, we obtain precise measurements of the brightness temperatures of the Uranus and Saturn disks at effective frequencies of 149 and 219 GHz. For Uranus we obtain thermodynamic brightness temperatures 106.7 ± 2.2 K and 100.1 ± 3.1 K. For Saturn, we model the effects of the ring opacity and emission using a simple model and obtain resulting (unobscured) disk temperatures of 137.3 ± 3.2 K and 137.3 ± 4.7 K.

AB - We describe the measurement of the beam profiles and window functions for the Atacama Cosmology Telescope (ACT), which operated from 2007 to 2010 with kilopixel bolometer arrays centered at 148, 218, and 277 GHz. Maps of Saturn are used to measure the beam shape in each array and for each season of observations. Radial profiles are transformed to Fourier space in a way that preserves the spatial correlations in the beam uncertainty to derive window functions relevant for angular power spectrum analysis. Several corrections are applied to the resulting beam transforms, including an empirical correction measured from the final cosmic microwave background (CMB) survey maps to account for the effects of mild pointing variation and alignment errors. Observations of Uranus made regularly throughout each observing season are used to measure the effects of atmospheric opacity and to monitor deviations in telescope focus over the season. Using the WMAP-based calibration of the ACT maps to the CMB blackbody, we obtain precise measurements of the brightness temperatures of the Uranus and Saturn disks at effective frequencies of 149 and 219 GHz. For Uranus we obtain thermodynamic brightness temperatures 106.7 ± 2.2 K and 100.1 ± 3.1 K. For Saturn, we model the effects of the ring opacity and emission using a simple model and obtain resulting (unobscured) disk temperatures of 137.3 ± 3.2 K and 137.3 ± 4.7 K.

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