Volume 481, Number 2, April II 2008
|Page(s)||575 - 591|
|Published online||07 February 2008|
The dancing sky: 6 years of night-sky observations at Cerro Paranal*
European Southern Observatory (ESO), K. Schwarzschildstr. 2, 85748, Garching b. München, Germany e-mail: firstname.lastname@example.org
Accepted: 16 January 2008
Aims. This work provides the results of the first six years of operation by the systematic night-sky monitoring at ESO-Paranal (Chile).
Methods. The UBVRI night-sky brightness was estimated on about 10 000 VLT-FORS1 archival images, obtained on more than 650 separate nights, distributed over 6 years, and covering the descent from maximum to minimum of sunspot cycle n. 23. Additionally, a set of about 1000 low-resolution, optical, night-sky spectra were extracted and analysed.
Results. The unprecedented database discussed in this paper has led to detecting a clear seasonal variation of the broad-band night-sky brightness in the VRI passbands, similar to the well-known semi-annual oscillation of the Na I D doublet. The spectroscopic data demonstrate that this seasonality is common to all spectral features, with the remarkable exception of the OH rotational-vibrational bands. A clear dependency on the solar activity is detected in all passbands and is particularly pronounced in the U band, where the sky brightness decreased by ~0.6 mag arcsec-2 from maximum to minimum of solar cycle n. 23. No correlation is found between solar activity and the intensity of the Na I D doublet and the OH bands. A strong correlation between the intensity of N I 5200 Å and [OI]6300, 6364 Å is reported here for the first time. The paper also addresses the determination of the correlation time-scales with solar activity and the possible connection with the flux of charged particles emitted by the Sun.
Key words: atmospheric effects / site testing / techniques: photometric / techniques: spectroscopic
© ESO, 2008
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.