Long-term Observations of Uranus and Neptune at 90 GHz with the IRAM 30 m Telescope. Astron
received date; accepted date: 23/01/2008 Context. The planets Uranus and Neptune with small apparent diameters are primary calibration standards. Aims. We investigate their variability at ∼ 90GHz using archived data taken at the IRAM 30m telescope during the 20 years period 1985 to 2005. Methods. We...
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ftciteseerx:oai:CiteSeerX.psu:10.1.1.244.7575 2023-05-15T18:22:04+02:00 Long-term Observations of Uranus and Neptune at 90 GHz with the IRAM 30 m Telescope. Astron C. Kramer R. Moreno A. Greve The Pennsylvania State University CiteSeerX Archives 2008 application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.244.7575 http://arxiv.org/pdf/0801.4452v1.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.244.7575 http://arxiv.org/pdf/0801.4452v1.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://arxiv.org/pdf/0801.4452v1.pdf Key words. Planets- Uranus- Neptune text 2008 ftciteseerx 2016-01-07T19:23:50Z received date; accepted date: 23/01/2008 Context. The planets Uranus and Neptune with small apparent diameters are primary calibration standards. Aims. We investigate their variability at ∼ 90GHz using archived data taken at the IRAM 30m telescope during the 20 years period 1985 to 2005. Methods. We calibrate the planetary observations against non-variable secondary standards (NGC7027, NGC 7538, W3OH, K3-50A) observed almost simultaneously. Results. Between 1985 and 2005, the viewing angle of Uranus changed from south-pole to equatorial. We find that the disk brightness temperature declines by almost 10 % ( ∼ 2σ) over this time span indicating that the south-pole region is significantly brighter than average. Our finding is consistent with recent long-term radio observations at 8.6GHz by Klein & Hofstadter (2006). Both data sets do moreover show a rapid decrease of the Uranus brightness temperature during the year 1993, indicating a temporal, planetary scale change. We do not find indications for a variation of Neptune’s brightness temperature at the 8% level. Conclusions. If Uranus is to be used as calibration source, and if accuracies better than 10 % are required, the Uranus sub-earth point latitude needs to be taken into account. Text South pole Unknown South Pole |
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Key words. Planets- Uranus- Neptune |
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Key words. Planets- Uranus- Neptune C. Kramer R. Moreno A. Greve Long-term Observations of Uranus and Neptune at 90 GHz with the IRAM 30 m Telescope. Astron |
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Key words. Planets- Uranus- Neptune |
description |
received date; accepted date: 23/01/2008 Context. The planets Uranus and Neptune with small apparent diameters are primary calibration standards. Aims. We investigate their variability at ∼ 90GHz using archived data taken at the IRAM 30m telescope during the 20 years period 1985 to 2005. Methods. We calibrate the planetary observations against non-variable secondary standards (NGC7027, NGC 7538, W3OH, K3-50A) observed almost simultaneously. Results. Between 1985 and 2005, the viewing angle of Uranus changed from south-pole to equatorial. We find that the disk brightness temperature declines by almost 10 % ( ∼ 2σ) over this time span indicating that the south-pole region is significantly brighter than average. Our finding is consistent with recent long-term radio observations at 8.6GHz by Klein & Hofstadter (2006). Both data sets do moreover show a rapid decrease of the Uranus brightness temperature during the year 1993, indicating a temporal, planetary scale change. We do not find indications for a variation of Neptune’s brightness temperature at the 8% level. Conclusions. If Uranus is to be used as calibration source, and if accuracies better than 10 % are required, the Uranus sub-earth point latitude needs to be taken into account. |
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The Pennsylvania State University CiteSeerX Archives |
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Text |
author |
C. Kramer R. Moreno A. Greve |
author_facet |
C. Kramer R. Moreno A. Greve |
author_sort |
C. Kramer |
title |
Long-term Observations of Uranus and Neptune at 90 GHz with the IRAM 30 m Telescope. Astron |
title_short |
Long-term Observations of Uranus and Neptune at 90 GHz with the IRAM 30 m Telescope. Astron |
title_full |
Long-term Observations of Uranus and Neptune at 90 GHz with the IRAM 30 m Telescope. Astron |
title_fullStr |
Long-term Observations of Uranus and Neptune at 90 GHz with the IRAM 30 m Telescope. Astron |
title_full_unstemmed |
Long-term Observations of Uranus and Neptune at 90 GHz with the IRAM 30 m Telescope. Astron |
title_sort |
long-term observations of uranus and neptune at 90 ghz with the iram 30 m telescope. astron |
publishDate |
2008 |
url |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.244.7575 http://arxiv.org/pdf/0801.4452v1.pdf |
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http://arxiv.org/pdf/0801.4452v1.pdf |
op_relation |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.244.7575 http://arxiv.org/pdf/0801.4452v1.pdf |
op_rights |
Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
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1766201415998373888 |