Long-term observations of Uranus and Neptune at 90 GHz with the IRAM 30m telescope - (1985 -- 2005)
The planets Uranus and Neptune with small apparent diameters are primary calibration standards. We investigate their variability at ~90 GHz using archived data taken at the IRAM 30m telescope during the 20 years period 1985 to 2005. We calibrate the planetary observations against non-variable second...
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ftdatacite:10.48550/arxiv.0801.4452 2023-05-15T18:22:02+02:00 Long-term observations of Uranus and Neptune at 90 GHz with the IRAM 30m telescope - (1985 -- 2005) Kramer, C. Moreno, R. Greve, A. 2008 https://dx.doi.org/10.48550/arxiv.0801.4452 https://arxiv.org/abs/0801.4452 unknown arXiv https://dx.doi.org/10.1051/0004-6361:20077705 Assumed arXiv.org perpetual, non-exclusive license to distribute this article for submissions made before January 2004 http://arxiv.org/licenses/assumed-1991-2003/ Astrophysics astro-ph FOS Physical sciences article-journal Article ScholarlyArticle Text 2008 ftdatacite https://doi.org/10.48550/arxiv.0801.4452 https://doi.org/10.1051/0004-6361:20077705 2022-04-01T16:08:04Z The planets Uranus and Neptune with small apparent diameters are primary calibration standards. We investigate their variability at ~90 GHz using archived data taken at the IRAM 30m telescope during the 20 years period 1985 to 2005. We calibrate the planetary observations against non-variable secondary standards (NGC7027, NGC7538, W3OH, K3-50A) observed almost simultaneously. 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% (~2sigma) 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 8.6 GHz 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. 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. : accepted for publication in A&A Text South pole DataCite Metadata Store (German National Library of Science and Technology) South Pole |
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Astrophysics astro-ph FOS Physical sciences |
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Astrophysics astro-ph FOS Physical sciences Kramer, C. Moreno, R. Greve, A. Long-term observations of Uranus and Neptune at 90 GHz with the IRAM 30m telescope - (1985 -- 2005) |
topic_facet |
Astrophysics astro-ph FOS Physical sciences |
description |
The planets Uranus and Neptune with small apparent diameters are primary calibration standards. We investigate their variability at ~90 GHz using archived data taken at the IRAM 30m telescope during the 20 years period 1985 to 2005. We calibrate the planetary observations against non-variable secondary standards (NGC7027, NGC7538, W3OH, K3-50A) observed almost simultaneously. 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% (~2sigma) 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 8.6 GHz 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. 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. : accepted for publication in A&A |
format |
Text |
author |
Kramer, C. Moreno, R. Greve, A. |
author_facet |
Kramer, C. Moreno, R. Greve, A. |
author_sort |
Kramer, C. |
title |
Long-term observations of Uranus and Neptune at 90 GHz with the IRAM 30m telescope - (1985 -- 2005) |
title_short |
Long-term observations of Uranus and Neptune at 90 GHz with the IRAM 30m telescope - (1985 -- 2005) |
title_full |
Long-term observations of Uranus and Neptune at 90 GHz with the IRAM 30m telescope - (1985 -- 2005) |
title_fullStr |
Long-term observations of Uranus and Neptune at 90 GHz with the IRAM 30m telescope - (1985 -- 2005) |
title_full_unstemmed |
Long-term observations of Uranus and Neptune at 90 GHz with the IRAM 30m telescope - (1985 -- 2005) |
title_sort |
long-term observations of uranus and neptune at 90 ghz with the iram 30m telescope - (1985 -- 2005) |
publisher |
arXiv |
publishDate |
2008 |
url |
https://dx.doi.org/10.48550/arxiv.0801.4452 https://arxiv.org/abs/0801.4452 |
geographic |
South Pole |
geographic_facet |
South Pole |
genre |
South pole |
genre_facet |
South pole |
op_relation |
https://dx.doi.org/10.1051/0004-6361:20077705 |
op_rights |
Assumed arXiv.org perpetual, non-exclusive license to distribute this article for submissions made before January 2004 http://arxiv.org/licenses/assumed-1991-2003/ |
op_doi |
https://doi.org/10.48550/arxiv.0801.4452 https://doi.org/10.1051/0004-6361:20077705 |
_version_ |
1766201381431017472 |