First ground-based 200-μm observing with THUMPER on JCMT - Sky characterization and planet maps

D. Ward-Thompson, P. A R Ade, H. Araujo, I. Coulson, J. Cox, G. R. Davis, Rh Evans, M. J. Griffin, W. K. Gear, P. Hargrave, P. Hargreaves, D. Hayton, B. J. Kiernan, S. J. Leeks, Philip Mauskopf, D. Naylor, N. Potter, S. A. Rinehart, R. Sudiwala, C. R. TuckerR. J. Walker, S. L. Watkin

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

We present observations that were carried out with the Two HUndred Micron PhotometER (THUMPER) mounted on the James Clerk Maxwell Telescope (JCMT) in Hawaii, at a wave-length of 200 μm (frequency 1.5 THz). The observations utilize a small atmospheric window that opens up at this wavelength under very dry conditions at high-altitude observing sites. The atmosphere was calibrated using the sky-dipping method and a relation was established between the optical depth, τ, at 1.5 THz and that at 225 GHz: τ 1.5THz = (95 ± 10) × τ 225GHz. Mars and Jupiter were mapped from the ground at this wavelength for the first time, and the system characteristics measured. A noise-equivalent flux density (NEFD) of ∼ 65 ± 10 Jy (1σ 1s) was measured for the THUMPER-JCMT combination, consistent with predictions based upon our laboratory measurements. The main beam resolution of 14 arcsec was confirmed and an extended error beam detected at roughly two-thirds of the magnitude of the main beam. Measurements of the Sun allow us to estimate that the fraction of the power in the main beam is ∼15 per cent, consistent with predictions based on modelling the dish surface accuracy. It is therefore shown that the sky over Mauna Kea is suitable for astronomy at this wavelength under the best conditions. However, higher or drier sites should have a larger number of useable nights per year.

Original languageEnglish (US)
Pages (from-to)843-848
Number of pages6
JournalMonthly Notices of the Royal Astronomical Society
Volume364
Issue number3
DOIs
StatePublished - Dec 11 2005
Externally publishedYes

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photometer
photometers
sky
planets
planet
telescopes
wavelength
wavelengths
atmospheric windows
parabolic reflectors
high altitude
astronomy
prediction
predictions
dipping
Jupiter (planet)
Jupiter
night
optical thickness
mars

Keywords

  • Infrared: Solar system
  • Instrumentation: photometers
  • Submillimetre
  • Techniques: photometric

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Ward-Thompson, D., Ade, P. A. R., Araujo, H., Coulson, I., Cox, J., Davis, G. R., ... Watkin, S. L. (2005). First ground-based 200-μm observing with THUMPER on JCMT - Sky characterization and planet maps. Monthly Notices of the Royal Astronomical Society, 364(3), 843-848. https://doi.org/10.1111/j.1365-2966.2005.09625.x

First ground-based 200-μm observing with THUMPER on JCMT - Sky characterization and planet maps. / Ward-Thompson, D.; Ade, P. A R; Araujo, H.; Coulson, I.; Cox, J.; Davis, G. R.; Evans, Rh; Griffin, M. J.; Gear, W. K.; Hargrave, P.; Hargreaves, P.; Hayton, D.; Kiernan, B. J.; Leeks, S. J.; Mauskopf, Philip; Naylor, D.; Potter, N.; Rinehart, S. A.; Sudiwala, R.; Tucker, C. R.; Walker, R. J.; Watkin, S. L.

In: Monthly Notices of the Royal Astronomical Society, Vol. 364, No. 3, 11.12.2005, p. 843-848.

Research output: Contribution to journalArticle

Ward-Thompson, D, Ade, PAR, Araujo, H, Coulson, I, Cox, J, Davis, GR, Evans, R, Griffin, MJ, Gear, WK, Hargrave, P, Hargreaves, P, Hayton, D, Kiernan, BJ, Leeks, SJ, Mauskopf, P, Naylor, D, Potter, N, Rinehart, SA, Sudiwala, R, Tucker, CR, Walker, RJ & Watkin, SL 2005, 'First ground-based 200-μm observing with THUMPER on JCMT - Sky characterization and planet maps', Monthly Notices of the Royal Astronomical Society, vol. 364, no. 3, pp. 843-848. https://doi.org/10.1111/j.1365-2966.2005.09625.x
Ward-Thompson, D. ; Ade, P. A R ; Araujo, H. ; Coulson, I. ; Cox, J. ; Davis, G. R. ; Evans, Rh ; Griffin, M. J. ; Gear, W. K. ; Hargrave, P. ; Hargreaves, P. ; Hayton, D. ; Kiernan, B. J. ; Leeks, S. J. ; Mauskopf, Philip ; Naylor, D. ; Potter, N. ; Rinehart, S. A. ; Sudiwala, R. ; Tucker, C. R. ; Walker, R. J. ; Watkin, S. L. / First ground-based 200-μm observing with THUMPER on JCMT - Sky characterization and planet maps. In: Monthly Notices of the Royal Astronomical Society. 2005 ; Vol. 364, No. 3. pp. 843-848.
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T1 - First ground-based 200-μm observing with THUMPER on JCMT - Sky characterization and planet maps

AU - Ward-Thompson, D.

AU - Ade, P. A R

AU - Araujo, H.

AU - Coulson, I.

AU - Cox, J.

AU - Davis, G. R.

AU - Evans, Rh

AU - Griffin, M. J.

AU - Gear, W. K.

AU - Hargrave, P.

AU - Hargreaves, P.

AU - Hayton, D.

AU - Kiernan, B. J.

AU - Leeks, S. J.

AU - Mauskopf, Philip

AU - Naylor, D.

AU - Potter, N.

AU - Rinehart, S. A.

AU - Sudiwala, R.

AU - Tucker, C. R.

AU - Walker, R. J.

AU - Watkin, S. L.

PY - 2005/12/11

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N2 - We present observations that were carried out with the Two HUndred Micron PhotometER (THUMPER) mounted on the James Clerk Maxwell Telescope (JCMT) in Hawaii, at a wave-length of 200 μm (frequency 1.5 THz). The observations utilize a small atmospheric window that opens up at this wavelength under very dry conditions at high-altitude observing sites. The atmosphere was calibrated using the sky-dipping method and a relation was established between the optical depth, τ, at 1.5 THz and that at 225 GHz: τ 1.5THz = (95 ± 10) × τ 225GHz. Mars and Jupiter were mapped from the ground at this wavelength for the first time, and the system characteristics measured. A noise-equivalent flux density (NEFD) of ∼ 65 ± 10 Jy (1σ 1s) was measured for the THUMPER-JCMT combination, consistent with predictions based upon our laboratory measurements. The main beam resolution of 14 arcsec was confirmed and an extended error beam detected at roughly two-thirds of the magnitude of the main beam. Measurements of the Sun allow us to estimate that the fraction of the power in the main beam is ∼15 per cent, consistent with predictions based on modelling the dish surface accuracy. It is therefore shown that the sky over Mauna Kea is suitable for astronomy at this wavelength under the best conditions. However, higher or drier sites should have a larger number of useable nights per year.

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KW - Infrared: Solar system

KW - Instrumentation: photometers

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